World of Ham Radio 1997/WOHR97_AmSoft_(1997-02-01).iso/usenets/1996_04/_antenna.txt

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The World of Ham Radio CD-ROM



From [e-mail] Fri Apr 05 16:13:25 1996
From: [e-mail] (WB3U)
Newsgroups: rec.radio.amateur.antenna
Subject: Re: "floating" the output of a tuner.
Date: Mon, 01 Apr 96 19:45:36 GMT
Message-ID: <4jpc67$[e-mail]>
References: <4jntnp$[e-mail]>

Newsgroup Post / CC by Mail

  Isaac wrote:

>Would it be possible to add a balun (1:1 or otherwise) to the input
>of the H network and therefore have an unbalanced-to-balanced-tuner??

Yes, but this doesn't fully resolve the problem.  High common-mode
voltage can still appear on the feedline and it can create common-mode
current that flows through the tuner with little or no attenuation.
Even if the tuner components are entirely isolated from ground, the
balun, through its interwinding capacitance, provides a path for
the current to reach the transmitter and chassis.

Thus, despite the fact that the balun is at the input of the tuner, it
can still fail to prevent RF current from flowing on grounds inside
the shack.  In addition, the tuner may provide little or no
attenuation of off-frequency signals that are carried in the form of
common-mode current.

A properly designed link-coupled tuner does not exhibit these
shortcomings.  There is very little capacitance between the input link
and the balanced output windings, therefore common-mode current is
prevented from flowing between the rig and feedline. I learned this
the hard way in my own system, in addition to being thoroughly
beaten-up with this concept during an earlier discussion. ;)

On a more positive note, I've met a number of hams on the air using
the system you described, although they were all using balanced L
networks rather than an H.  None of them were experiencing any
significant symptoms of common-mode current.

From this, it appears that placing the balun ahead of a balanced L/C
network is definitely useful when common-mode voltage is not a
concern.  This location protects the balun from high differential
voltage, and is at least more likely to provide satisfactory results
than when the balun is attached directly to the feedline.

73,
Jack  WB3U


From [e-mail] Fri Apr 05 16:13:26 1996
From: [e-mail] (CHARLES J. MICHAELS)
Newsgroups: rec.radio.amateur.antenna
Subject: Re: "floating" the output of a tuner.
Date: 1 Apr 1996 06:39:53 GMT
Message-ID: <4jntnp$[e-mail]>


Isaac wrote -

Would it be possible to add a balun (1:1 or otherwise) to the input of
the H network and therefore have an unbalanced-to-balanced-tuner??
That way, you could combine the transition from coax to balanced with
the tuner.  Anyway, doesn't it make sense that the place where you
switch from one impedance line to another is the same place where you
tune impedances??

Just a thought....
Isaac

Isaac,
        If for single band opertion, you generally wouldn't need an
H net.  Two L nets with the shunt element common to both is simpler.
The shunt element may be on the input side or the line side depending
on the frequency.  However to design the L nets you must have some
idea of the approximatel impedance of the line input.  You can then
fine tune it to get exact values for fixed components.
        However if you want to use it for multiband operation you
must either be able to switch appropriate L nets for each band or
use variable elements and be able to switch the proper one into shunt
on the input or line side as appropriate to each band.
        I have a friend who built the coils and capacitors on Poly
sheets with bannana jacks and plugs and plugs the proper one in for
each band.  Use a rod core balun on the input side .

Charlie,  W7XC
--


From [e-mail] Fri Apr 05 16:13:27 1996
From: [e-mail] (WB3U)
Newsgroups: rec.radio.amateur.antenna
Subject: Re: "floating" the output of a tuner.
Date: Tue, 02 Apr 96 19:59:36 GMT
Message-ID: <4js1ct$[e-mail]>
References: <4jntnp$[e-mail]> <4jrli6$[e-mail]>

Post / CC by Mail

   Cecil Moore <[e-mail]> wrote:

>On my antenna, I share a single variable capacitor on 20m, 17m, 15m,
>12m, and 10m. 40m requires one toroidal inductor and 80m requires
>two. These single reactances cause a Z0-match on the ladder-line so
>my balun *always* sees a purely resistive 300 ohms. In this case,
>minimum components equals minimum loss equals win/win.

Hi Cecil,

Do you know of a way to measure the common-mode voltage on these
systems?  If it's not sufficient to create significant current flow
through the balun or to ground, it wouldn't show up even if individual
current pickups were used on each side of the line.

I realize this scenario would mean that common-mode voltage isn't
causing a problem.  However, it would still be potentially useful to
know how much can be tolerated on each frequency by a particular balun
before conduction through the windings causes the system to become
unbalanced.

73,
Jack  WB3U


From [e-mail] Fri Apr 05 16:13:28 1996
From: Cecil Moore <[e-mail]>
Newsgroups: rec.radio.amateur.antenna
Subject: Re: "floating" the output of a tuner.
Date: 2 Apr 1996 16:44:54 GMT
Message-ID: <4jrli6$[e-mail]>
References: <4jntnp$[e-mail]>

[e-mail] (CHARLES J. MICHAELS) wrote:
>
>>Isaac wrote -
>>
>>Would it be possible to add a balun (1:1 or otherwise) to the input of
>>the H network and therefore have an unbalanced-to-balanced-tuner??

>However to design the L nets you must have some
>idea of the approximatel impedance of the line input.  You can then
>fine tune it to get exact values for fixed components.

Hi Charlie, a very good approximation of the balanced line input
impedance can be had with a pick up loop. Imax/Imin=SWR. If one
knows the location and *relative* magnitude of the Imax and Imin
points, one can calculate the SWR, velocity factor, and feedpoint
impedance. After that, you don't even need an L network. A single
type of reactance will do if placed at the proper point and a pick
up loop will tell you exactly where that point is. On my antenna,
I share a single variable capacitor on 20m, 17m, 15m, 12m, and 10m.
40m requires one toroidal inductor and 80m requires two. These
single reactances cause a Z0-match on the ladder-line so my balun
*always* sees a purely resistive 300 ohms. In this case, minimum
components equals minimum loss equals win/win.

73, Cecil, KG7BK, OOTC  (not speaking for my employer)




From [e-mail] Fri Apr 05 16:13:30 1996
From: Cecil Moore <[e-mail]>
Newsgroups: rec.radio.amateur.antenna
Subject: Re: "floating" the output of a tuner.
Date: Wed, 3 Apr 96 09:00:39 -0500
Message-ID: <[e-mail]>
References: <[e-mail]> <4jtqn7$[e-mail]>

W8JI  Tom <[e-mail]> writes:

>radiating like a Harley leaks oil!

Hey Buddy, you can insult me or my antenna but flaming my Harley
is stepping over the line!


From [e-mail] Fri Apr 05 16:13:30 1996
From: Cecil Moore <[e-mail]>
Newsgroups: rec.radio.amateur.antenna
Subject: Re: "floating" the output of a tuner.
Date: Wed, 3 Apr 96 21:54:40 -0500
Message-ID: <[e-mail]>
References: <[e-mail]> <4jtqn7$[e-mail]> <[e-mail]> <4jutc5$[e-mail]>

WB3U <[e-mail]> writes:

>I don't think it was an insult Cecil.  Leaving your mark when you park
>a Harley lets other drivers know who owns that parking spot.  If my

Hi Jack, I get it - kinda like a wolf marking its territory.


From [e-mail] Fri Apr 05 16:13:31 1996
From: [e-mail] (Dale Chidester)
Newsgroups: rec.radio.amateur.antenna
Subject: Re: A 2-cent antenna for 2-mtrs
Date: 4 Apr 1996 16:11:42 GMT
Message-ID: <4k0sbu$[e-mail]>
References: <[e-mail]>
Reply-To: [e-mail]

In article [e-mail], Carl Estey <[e-mail]> w
rites:
...
 A penny was soldered on each end of the tubing to for the
"plates" of a capacitor.

...

If you try to repeat this today, be sure to use "old" pennies.  Some time in t
he
70's they changed from all copper to copper plated zink!

        73
                Dale




From [e-mail] Fri Apr 05 16:13:32 1996
From: Ken Neal <[e-mail]>
Newsgroups: rec.radio.amateur.antenna
Subject: Antenna Farm
Date: Fri, 05 Apr 1996 20:55:41 -0400
Message-ID: <[e-mail]>
Reply-To: [e-mail]

The messages regarding constructing a tower base in cental Texas prompts
me to send this request.

Within the next 12 months I will be retiring and moving to central
Texas, the hill country, if all works out.  I plan to buy enough land to
put up all the antennas I want.  Like most of you, I have seen these
wonderful photos on the cover of CQ, QST, etc. showing these amazing
towers and all the antennas they support.

My question is this.  If space and money were no object what kind of
antenna farm should a person put up?

I work mostly dx on digital modes, cw and phone.  I work from 160 thru
10 meters.

How many towers and what goes on each?  Stacked mono-banders?  Stacked
tri-banders.  No stacked arrays?  What is best for 160, separate receive
and transmit antennas?  How about 80?

I am not in a hurry for a quick answer, I hope everyone puts in their 2
cents so I can come up with the best solution.  I don't have unlimited
funds, but is something gets too expensive we can explore less
expensive, but acceptable solutions.

Thanks in advance for your help.

Ken Neal - KM4BW


From [e-mail] Fri Apr 05 16:13:34 1996
Newsgroups: rec.radio.amateur.antenna
From: Paul Moller <[e-mail]>
Subject: Re: Antenna Modeling Software
Date: Tue, 02 Apr 1996 13:01:37 -0600
Message-ID: <[e-mail]>
References: <4jpj3j$[e-mail]>

CHARLES J. MICHAELS wrote:
>
> Scott asked
> A nyone know what software is available for antenna modeling and
> design?  The only thing I have ever heard of was the ARRL "Method of
> Moments" software.  But, I can't seem to find any reference to it.
> Ideas?
>
> Scott -  See Roy Lewallen's ads for ELNEC and EZNEC
>
> Charlie,  W7XC
> --

Try NEC-Win Basic from Paragon Technology, they can be reached by email
at [e-mail] (Joseph Finnerty). Their product looks good and is
very cost effective.

[e-mail]


From [e-mail] Fri Apr 05 16:13:35 1996
Newsgroups: rec.radio.amateur.antenna
From: Ron Lile <[e-mail]>
Subject: Re: Antenna Modeling Software
Message-ID: <[e-mail]>
References: <4jpj3j$[e-mail]> <[e-mail]>
Date: Wed, 3 Apr 1996 19:41:30 GMT

Paul Moller <[e-mail]> wrote:
>
> CHARLES J. MICHAELS wrote:
> >
> > Scott asked
> > A nyone know what software is available for antenna modeling and
> > design?  The only thing I have ever heard of was the ARRL "Method of
> > Moments" software.  But, I can't seem to find any reference to it.
> > Ideas?
> >
> > Scott -  See Roy Lewallen's ads for ELNEC and EZNEC
> >
> > Charlie,  W7XC
> > --
>
> Try NEC-Win Basic from Paragon Technology, they can be reached by email
> at [e-mail] (Joseph Finnerty). Their product looks good and is
> very cost effective.
>
> [e-mail]
Another 2cents worth -- I have both EZNEC and NEC-Win and although EZNEC is
DOS based, I find it much more freindly in terms of operational characteristic
s
and find NEC-Win (basic) to be only windows fancy and not as functionally
clean as I would have expected.  To have to go through the whole plot routine
again for each change in the antenna design is not what I would call as
neat as what you get with EZNEC. I understand that Paragon is to come
out with a fancier version, but I would like to see the basic version do
afew things more cleanly.

For just afew more bucks, Brian Beezely (sp?) has a couple of optimization
programs which although I have not used the full blown versions, look like
they can provide decent results for the plug and crank types.

Ron K0RL
[e-mail]


From [e-mail] Fri Apr 05 16:13:36 1996
From: [e-mail]
Newsgroups: rec.radio.amateur.antenna
Subject: antenna problems
Date: Tue, 02 Apr 96 17:50:15 GMT
Message-ID: <4jr75n$[e-mail]>

my first post was not clear here it is again
I have a inverted v the apex is 35' the ends are around 5' to 7' off the
ground it is fed with rg-58 hooked direct to the antenna it is cut for the
novice 80m band The rig is a ic725 thru a mfj-949e tuner.
both the rig and the tuner are grounded. I get only a small amount of power on

any band usuelly less than 50 watts.
I have a 10m vert. when I use this I go to bypass mode on the tuner I get 110
watts out.
I note that when I tuch my knobs on the metal disk i get a definate noise
increse but only on the inverted v.
I hope someone can help me out thanks
Billy
KD4DPB



From [e-mail] Fri Apr 05 16:13:37 1996
Newsgroups: rec.radio.amateur.antenna
From: Monty Wilson <[e-mail]>
Subject: Re: antenna problems
Message-ID: <[e-mail]>
Date: Tue, 2 Apr 1996 19:04:06 GMT
References: <4jr75n$[e-mail]>

[e-mail] wrote:
>my first post was not clear here it is again
>I have a inverted v the apex is 35' the ends are around 5' to 7' off the
>ground it is fed with rg-58 hooked direct to the antenna it is cut for the
>novice 80m band The rig is a ic725 thru a mfj-949e tuner.
>both the rig and the tuner are grounded. I get only a small amount of power o
n
>any band usuelly less than 50 watts.
>I have a 10m vert. when I use this I go to bypass mode on the tuner I get 110

>watts out.
>I note that when I tuch my knobs on the metal disk i get a definate noise
>increse but only on the inverted v.

Let's start with the band for which the antenna is cut.  Especially if in
the past you have had it work on this band.  Switch your tuner to "bypass"
and select the dipole.  Check the VSWR on the band for which the antenna is
cut; in this case, 80m novice band.  Use only a small amount of power for
this test.

If the VSWR is less than 3:1, then the antenna connections and coax are OK
and you have a problem with your tuner, your tuner setup, or RF in the shack.

If the VSWR is greater than 3:1 across the band you thought the antenna was
cut for (and particularly if you have had it work in the past in this band)
then you have a bad connection at one end of the coax, or you have a broken
center conductor in the coax.  If you disassemble each end of the coax and
do not find a problem, maybe you should buy or borrow another feedline and
test the antenna again.

Did I miss anything fellas?

--
.........Monty.
[e-mail]




From [e-mail] Fri Apr 05 16:13:38 1996
From: [e-mail] (WB3U)
Newsgroups: rec.radio.amateur.antenna
Subject: Re: antenna problems
Date: Wed, 03 Apr 96 08:33:02 GMT
Message-ID: <4jtdhj$[e-mail]>
References: <4jr75n$[e-mail]> <[e-mail]>

   Monty Wilson <[e-mail]> wrote:
>[e-mail] wrote:

>>I have a inverted v the apex is 35' the ends are around 5' to 7' off
>>the ground it is fed with rg-58 hooked direct to the antenna it is
>>cut for the novice 80m band The rig is a ic725 thru a mfj-949e
>>tuner.  both the rig and the tuner are grounded. I get only a small
>>amount of power on any band usuelly less than 50 watts.
             <snip>
>>I note that when I tuch my knobs on the metal disk i get a definate
>>noise increse but only on the inverted v.

>If the VSWR is less than 3:1, then the antenna connections and coax
>are OK and you have a problem with your tuner, your tuner setup, or
>RF in the shack.

That's a good procedure.  I would just add that if the SWR is
reasonable in bypass mode and the tuner is able to achieve a 1:1 SWR
at the rig, this is almost certainly due to RF current on the chassis
of the rig.  If so, the next step would be the installation of a
current balun at the feedpoint of the dipole. Once that's done and the
antenna system is working correctly, it should be possible to operate
the rig with no RF ground at all, with no ill effects.

Remember that the balun may see too high an impedance on bands other
than 80M, so the problem may still be evident on those bands.  The
balun won't provide a multiband solution unless it's applied to a
true multiband antenna system.

73,
Jack  WB3U


From [e-mail] Fri Apr 05 16:13:39 1996
From: [e-mail] (JCHol)
Newsgroups: rec.radio.amateur.antenna
Subject: Re: Antenna Restrictive Covenants- FCC Submission
Date: 1 Apr 1996 12:04:45 -0500
Message-ID: <4jp2bd$[e-mail]>
References: <4jhkuq$[e-mail]>
Reply-To: [e-mail] (JCHol)

Bravo!  I moved to my present location from a "fully" restricted
neighborhood.  The present location has no antenna or transmitter
restrictions, but my choice was quite limited.  And I will not be able to
live here and maintain the place in my old age.

73 de John, WA5TWL


From [e-mail] Fri Apr 05 16:13:41 1996
From: [e-mail] (Jim Weir)
Newsgroups: rec.radio.amateur.antenna
Subject: Re: Antennas in PVC pipe
Date: Wed, 03 Apr 1996 16:04:18 GMT
Message-ID: <4ju7o5$[e-mail]>
References: <[e-mail]>

[e-mail] (Randal Olds) shared the following priceless
pearls of wisdom:

>JT>Today started to assemble a J-pole antenna for 224 MHz.  Used number
>JT>12 solid wire and planned on enclosing it inside a length of 1 in dia
>JT>PVC pipe.  Using a grid dip meter, cut the antenna to resonate on 224.

Yeah, that's just about right. You've got a PVC dielectric loading of
your antenna.  Suppose that the PVC was ten feet thick.  Then the
foreshortening of the antenna would be somewhere around the square
root of the dielectric constant of PVC.  Making it thinner just
reduces the effect.

However, had you chosen to put the antenna on the OUTSIDE of the pipe,
there is no dielectric loading effect because you are then matching
directly between the antenna elements and free space.  The substrate
is at best a second or third order effect.

>The only experience I've had with pvc pipe is with HF frequencies,
>schedule 80 pvc is grey and doesn't work well with RF it tends to heat
>up.

I'd be interested in seeing your actual test results, not what you've
seen from other sources.  I haven't yet seen a FIRST HAND report of
frequencies, power levels, and temperature rise.

> I've used schedule 40 white pvc and it seems to be ok on HF.

And I've used white, gray, and black without a lot of difference at
HF.  At VHF there seems to be a minor difference in the dielectric
constant, but not in the loss.

Jim


Jim Weir VP Engineering | You bet your sweet patootie I speak for the
RST Engineering         | company.  If I don't, ain't nobody gonna.
Grass Valley CA 95945   |
http://www.rst-engr.com | AR Adv WB6BHI--FCC 1/C phone--Cessna 182A N73CQ
[e-mail]        | Commercial/CFI-Airplane/Glider-----A&P Mechanic



From [e-mail] Fri Apr 05 16:13:42 1996
From: Mark Mansfield <[e-mail]>
Newsgroups: rec.radio.amateur.antenna
Subject: Any homebrew scanner antenna plans available?
Date: Mon, 01 Apr 1996 14:00:07 -0600
Message-ID: <[e-mail]>

Does anyone know if there is any web or ftp sites that have plans for
wideband scanner antennas?
Thanks in advance,
Mark


From [e-mail] Fri Apr 05 16:13:42 1996
From: Cecil Moore <[e-mail]>
Newsgroups: rec.radio.amateur.antenna
Subject: Average Current on Ladder-Line
Date: 2 Apr 1996 16:58:22 GMT
Message-ID: <4jrmbe$[e-mail]>

I have waded through all the books I have access to and can't
find the answer to the following question:

Assuming I use a pickup loop to measure a voltage proportional
to the maximum current and minimum current on ladder-line, the
SWR is then Imax/Imin. What then, is the average current? Is it
(Imax+Imin)/2 ? SQRT(Imax*Imin) ? Help somebody...

73, Cecil, KG7BK, OOTC  (not speaking for my employer)




From [e-mail] Fri Apr 05 16:13:44 1996
From: [e-mail] (WB3U)
Newsgroups: rec.radio.amateur.antenna
Subject: Re: Average Current on Ladder-Line
Date: Wed, 03 Apr 96 07:46:06 GMT
Message-ID: <4jtapl$[e-mail]>
References: <4jrmbe$[e-mail]>

Post / CC by Mail

   Cecil Moore <[e-mail]> wrote:

>I have waded through all the books I have access to and can't
>find the answer to the following question:
>
>Assuming I use a pickup loop to measure a voltage proportional
>to the maximum current and minimum current on ladder-line, the
>SWR is then Imax/Imin. What then, is the average current? Is it
>(Imax+Imin)/2 ? SQRT(Imax*Imin) ? Help somebody...

Hi Cecil,

I had some trouble visualizing this at first, but I think the answer
lies in the *transition* between the node and the loop.

To explain what I mean, let's select a point on the line that's
physically centered between the locations of Imin and Imax.  Let's
call that point Icenter.

Next, consider that regardless of the exact current curve (sine?) that
occurs as you move along the line from Imin to Imax, the "half" curves
between Imin and Icenter, and between Icenter and Imax, will be
identical mirror images of each other.  Therefore, the current at
Icenter will be equal to (Imax + Imin)/2 and it represents the
average.

Is this the concept of average current that you had in mind, or have I
oversimplified?

73,
Jack  WB3U


From [e-mail] Fri Apr 05 16:13:44 1996
From: Cecil Moore <[e-mail]>
Newsgroups: rec.radio.amateur.antenna
Subject: Re: Average Current on Ladder-Line
Date: Wed, 3 Apr 96 21:51:00 -0500
Message-ID: <[e-mail]>
References: <4jtapl$[e-mail]> <4ju3pd$[e-mail]>

W8JI  Tom <[e-mail]> writes:

>I agree with Jack. The average current is Imax + Imin / 2
>
>The current spends "exactly the same time" hovering around minimum as it
>does maximum.

Hi Tom, that's what I thought at first but if the waveforms in
the ARRL antenna book are correct, the SWR current waveform looks
somewhat like a rectified sine wave. Guess we would have to agree
on what "average" means. What I had in mind was the component of
the current that gets radiated and that is apparently sqrt(Imax*Imin).
Back when dinosaurs still roamed the earth, I looked at SWR curves
on a scope and it looked like a jump rope in action.

73, Cecil, KG7BK, OOTC


From [e-mail] Fri Apr 05 16:13:46 1996
From: [e-mail] (W8JI  Tom)
Newsgroups: rec.radio.amateur.antenna
Subject: Re: Average Current on Ladder-Line
Date: 4 Apr 1996 08:02:56 -0500
Message-ID: <4k0ha0$[e-mail]>
References: <[e-mail]>

In article <[e-mail]>, Cecil Moore
<[e-mail]> writes:

>
>Hi Tom, that's what I thought at first but if the waveforms in
>the ARRL antenna book are correct, the SWR current waveform looks
>somewhat like a rectified sine wave. Guess we would have to agree
>on what "average" means. What I had in mind was the component of
>the current that gets radiated and that is apparently sqrt(Imax*Imin).
>Back when dinosaurs still roamed the earth, I looked at SWR curves
>on a scope and it looked like a jump rope in action.
>
>73, Cecil, KG7BK, OOTC
>
>

Hi Cecil,

I never looked in any detail at the current distribution but intution told
me it was a sine shaped pattern.

Maybe that's wrong., or only true for low values of mismatch.

After all, the current and voltage are the sqr roots of a sine sqrd added
to a cosine squared.

73 Tom


From [e-mail] Fri Apr 05 16:13:47 1996
From: jaeschke <[e-mail]>
Newsgroups: rec.radio.amateur.antenna
Subject: Re: Average Current on Ladder-Line
Date: 3 Apr 1996 13:32:04 GMT
Message-ID: <4jtukk$[e-mail]>
References: <4jrmbe$[e-mail]>

Cecil

It seems to me that the answer to your question depends on how
your meter read the current in the first place and what type of
answer you want.

If your meter reads peak, and you want the average of the sine
wave of current then you must convert it by multiplying the
peak by .5.  If your meter reads RMS, and you want the average
of the sine wave of current then you must convert it by
multiplying the RMS by .7.

If you want the average current of the two points and your
meter reads either peak, RMS or average, then it is proper to
average the two readings.  My reasoning for the RMS reading
meter is that the match between the load and the line causes
the reflections which change the current from the average that
would flow in a perfectly matched line to the min and max
values that you measure.  Therefore it is proper to calculate
this "matched value", by averaging the RMS readings.  If you
would wish to calculate the effective power delivered by two
currents that flow in succession into a resistive load, then
you must average the square of the currents and take the square
root to get the effective current.

I hope that this helps

Jim




From [e-mail] Fri Apr 05 16:13:48 1996
From: [e-mail] (WB3U)
Newsgroups: rec.radio.amateur.antenna
Subject: Re: Carolina Windom 80 Question
Date: Mon, 01 Apr 96 19:04:08 GMT
Message-ID: <4jp9og$[e-mail]>
References: <4ipmvh$[e-mail]> <4jp185$[e-mail]>

   [e-mail] (JCHol) wrote:

>I have a Carolina Windom installed as a flattop at about 45 feet.  I
>am pleased with its broad band performance on 80 meters.  It also has
>fairly low swr on the other bands.  It doesn't outperform my other
>antennae such as beams, etc. but it puts out an acceptable signal.  I
>am unable to verify any of the claims about low angle magic
>radidation from the feedline portion except I believe I have
>benefited by it on 80 meters.

Do you have a radial system under the antenna?  If not, a considerable
portion of the signal from the vertical radiator is likely being
consumed in ground losses.  The broadband performance you've noted
may be a symptom of this effect.

>However, my inverted L on 80 meters is better for dx.
>Compared to the G5RV in the same installation, I think you would get
>better 80 meter performance and equivalent or marginally better
>performance on the other bands.

My 1947 Radio Handbook shows an antenna of almost identical
dimensions, dubbed an off-center fed doublet.  Naturally, the ferrite
devices aren't used.  The text states that the system works well over
highly conductive ground, but will introduce rather high losses when
the antenna is located above rocky or poorly conducting soil.  In
addition, the feeder is claimed to present an impedance against ground
of approximately 600 ohms, although this assumes the antenna is being
operated at it's fundamental or a harmonically-related frequency.

Is anyone able to model this?  The commercial version consists of a
single-conductor vertical radiator 22' long, attached to the dipole
off center.  One leg of the dipoole is 50', the other is 83'.  There's
a "matching unit" at the point where the vertical section connects to
the dipole, but I think for modeling purposes it could be omitted.
There's also a "line isolator" at the bottom of the vertical radiator
that allows feeding the system with coax.

I don't know what function the 3-terminal "matching unit" is intended
to serve, but I have some difficulty seeing this system as anything
more than a vertical with a hat.  If anyone cares to model it, I'd be
particularly interested to know the impedance seen by the ferrite-core
"line isolator" on the various bands.  This antenna is claimed to
operate from 80-10M, including WARC.

73,
Jack  WB3U


From [e-mail] Fri Apr 05 16:13:49 1996
From: [e-mail] (JCHol)
Newsgroups: rec.radio.amateur.antenna
Subject: Re: Carolina Windom 80 Question
Date: 1 Apr 1996 11:45:57 -0500
Message-ID: <4jp185$[e-mail]>
References: <4ipmvh$[e-mail]>
Reply-To: [e-mail] (JCHol)

I have a Carolina Windom installed as a flattop at about 45 feet.  I am
pleased with its broad band performance on 80 meters.  It also has fairly
low swr on the other bands.  It doesn't outperform my other antennae such
as beams, etc. but it puts out an acceptable signal.  I am unable to
verify any of the claims about low angle magic radidation from the
feedline portion except I believe I have benefited by it on 80 meters.
However, my inverted L on 80 meters is better for dx.
Compared to the G5RV in the same installation, I think you would get
better 80 meter performance and equivalent or marginally better
performance on the other bands.

73 de John, WA5TWL


From [e-mail] Fri Apr 05 16:13:50 1996
From: [e-mail] (Jason Reed)
Newsgroups: rec.radio.amateur.antenna
Subject: Re: Cushcraft AP8A & APR18A SWR problem
Date: Wed, 03 Apr 1996 20:42:41 GMT
Message-ID: <4jujtb$[e-mail]>
References: <4i4m77$[e-mail]>


>Hi there,
>       I have a cushcraft AP8A HF vertical antenna mounted on the gable end
>of my house and need to attach ground radials to it to get the SWR
>down to below 1:1.5 on all 8 bands.
>       I have the cushcraft APR18A radial kit and was wondering if anyone
>has had experience with the positioning of the many radials in the
>same mounting position as mine.
>       Obviously mounting the radials in one of the directions is impossible
>because there is no roof to support them.
>       Have you had the same problem and if so how did you overcome it?
>       Are there any designs of matching units which can be used at the base
>as in the R7 and R5 verticals which would do without the need for
>radials?

>       Your comments would be most welocme.

>       Many thanks in advance

>       73    Jason  GM0VKQ    QTH  Aberdeen Scotland UK







From [e-mail] Fri Apr 05 16:13:50 1996
From: [e-mail] (Wolfgang Gellerich)
Newsgroups: rec.radio.amateur.antenna
Subject: Experience with crossed field antennas?
Date: 4 Apr 1996 08:12:58 GMT
Distribution: world
Message-ID: <4k00aa$[e-mail]>

Recently, I got some articles about so-called crossed-field antennas. The
theory looks quite convincing and CFAs could have useful applications as they
are rather small, even on low bands. Does anyone have experience with these
kind of antenna?

vy 73, Wolfgang DJ3TZ




From [e-mail] Fri Apr 05 16:13:52 1996
From: [e-mail] (Roy Lewallen)
Newsgroups: rec.radio.amateur.antenna
Subject: Re: Field Day Special
Date: Wed, 03 Apr 96 11:59:45 GMT
Message-ID: <4jtp5o$[e-mail]>

[e-mail] (Douglas Rhodes):

>QST magazine had an article by W7EL about eight or ten years ago with
>description and dimensions for a modified ZL-special for twenty meters,
>which Roy Llewellyn called the Field Day Special. I've been using it
>happily for two years, but would like to try something different on twenty
>and re-cut the FD-special for 15 meters. Has anybody (including W7EL)
>re-modelled it for other bands?

There are a lot of things to trade with this antenna: gain, front/back,
beamwidth and SWR. One or more parameters can be optimized over a narrow
range of frequencies, or made reasonably good over a wider range. The
highest gain occurs with a relatively narrow beamwidth and poor front/back
ratio. I generally opt for a wide beamwidth and slightly lower gain, since
the ones I've built aren't rotatable. This can be done while maintaining a
good f/b ratio. In some cases a better design for the other parameters can
be achieved if the feedpoint impedance is permitted to move from 50 ohms
requiring simple matching (e.g., a series capacitor).

Here's a design which has moderate gain (around 4 dB over a dipole,
depending on height), a fairly wide beamwidth (about 70 degrees at -3dB),
and a fairly good f/b ratio (which will depend on the frequency of
operation). Fed with 50 ohm line and no matching, it should give an SWR of
2:1 or less from 21.0 to 21.35 MHz, and under 2.5 at 21.45.

Element lengths: 21'3"
Element spacing: 5'1"
"Phasing" line length: 5'3"

The entire antenna must be made from flat 300-ohm twinlead to work as
designed. Connect 50-ohm coax to the center of one element, using a current
balun at the feedpoint. Don't forget the half twist in the "phasing" line!

A slight modification permits switching the direction. Two feedlines are
used, one at the center of each element. One or the other is fed, to change
direction, with the unused one being left open-circuited.

Element lengths: 21'4"
Element spacing: 5'10"
"Phasing" line length: 6'0"
Feedline lengths: 55'3"

Again, the antenna is constructed entirely of flat 300-ohm twinlead,
INCLUDING THE TWO FEEDLINES. Any substitution or modification will change
the antenna's characteristics, perhaps seriously. The input impedance is
nominally 50 ohms at the bottom of the active feedline. A current balun
should be used where the 50-ohm line to the rig connects with the 300-ohm
feedline to the antenna. The characteristics of this antenna are similar to
the single-feedline version, except that the SWR bandwidth is a bit
narrower. It should give < 2:1 from 21.0 to 21.3, <2.5:1 to 2.35, <3:1 to
21.4, and about 3.2:1 at 21.45. (Note: These are the SWR on the 50-ohm line
to the rig, not the SWR on the 300-ohm feedlines, which will be much
higher.) If the antenna is lower than 55 feet, you'll have to figure out
what to do with the excess 300-ohm feedline. Don't coil it or lay it on the
ground.

SWR figures for both antennas may not be exactly as I've given, will be
lowered by feedline loss, and will vary some with antenna height. They
should be in the ballpark, however.

I've successfully used the FD Special at home for years on 20 and 15, and
on Field day on 20, 15, and 40. Took top in my class (1B battery - 2 op.)
one year when we managed to stay up all night and had FD Specials on all
three bands -- put up with slingshots at 80 feet.

Have fun!

73,
Roy Lewallen, W7EL


From [e-mail] Fri Apr 05 16:13:53 1996
From: John Fleming <[e-mail]>
Newsgroups: rec.radio.amateur.antenna
Subject: Hamsick or Outbacker?
Date: Wed, 03 Apr 1996 13:36:03 +0500
Message-ID: <[e-mail]>

Which is a better value?
How well does Outbacker Perth work,
particularly if I have to put it on back of a Saturn Sedan?
Anybody know if the trunk of a Saturn is truly grounded?
I know the sides are plastic.


From [e-mail] Fri Apr 05 16:13:54 1996
From: [e-mail] (pete brunelli)
Newsgroups: rec.radio.amateur.antenna
Subject: Re: Hamsick or Outbacker?
Date: Thu, 04 Apr 1996 16:06:04 GMT
Message-ID: <4k0ruv$[e-mail]>
References: <[e-mail]>

John Fleming <[e-mail]> wrote:

>Which is a better value?
>How well does Outbacker Perth work,
>particularly if I have to put it on back of a Saturn Sedan?
>Anybody know if the trunk of a Saturn is truly grounded?
>I know the sides are plastic.

John,
I have used the Perth for a year and it is a great little antenna.
However, it needs a solid connection to ground.  The hamstick is no
different in this regard.  Plan on running a length of braid from the
mount to the frame.

The Perth is heavier than a hamstick, but covers 80-10.  I know a few
folks who put 'em on heavy duty VHF mounts and they work ok.

What bands are you planning to be on?

GL




From [e-mail] Fri Apr 05 16:13:55 1996
From: "George J. Molnar" <[e-mail]>
Newsgroups: rec.radio.amateur.antenna
Subject: Re: Hamstick or Outbacker?
Date: Thu, 04 Apr 1996 07:52:09 -0700
Message-ID: <[e-mail]>
References: <[e-mail]>
Reply-To: [e-mail]
To: John Fleming <[e-mail]>

John Fleming wrote:
>
> Which is a better value?
> How well does Outbacker Perth work,
> particularly if I have to put it on back of a Saturn Sedan?
> Anybody know if the trunk of a Saturn is truly grounded?
> I know the sides are plastic.

Can't say about the Saturn, but I have tested the Outbacker, Hamstick,
Valor Pro Am, and Hustler whips. The Outbacker came in last, particularly
on the lower frequencies.

Don't get me wrong - it is a fine antenna, and you can make plenty of contacts
with it....it's just less effective than the Hustler (which I found to be the
best). The Pro Am just edges the Hamstick, but not by much. The Hustler typica
lly
weighs in at about an s-unit above the others, which all are actually quite
close in performance.

Try to get some kind of frame ground for your mobile mount. With mobile antenn
as,
and their attendant inefficiency, the best ground you can get is critical.

73!


--
George J. Molnar
Highlands Ranch, Colorado
Amateur Radio: KF2T@N0QCU.#NECO.CO.USA.NOAM
http://www.interealm.com/p/gmolnar/index.html


From [e-mail] Fri Apr 05 16:13:56 1996
From: [e-mail] (Gustavo D. Leizerovich)
Newsgroups: rec.radio.amateur.antenna
Subject: HF SSB Selective Call
Date: Fri, 5 Apr 1996 10:43:53
Message-ID: <[e-mail]>

HF-SSB Selective Call Units.
Brand new in the box.
Compatible with any SSB radio.
Excellent performance in poor S/N environments.
Ackback and Busy modes of operation.

Price:  $99 each

Gus Leizerovich
[e-mail]



From [e-mail] Fri Apr 05 16:13:57 1996
From: [e-mail] (Graham Seale)
Newsgroups: rec.radio.amateur.antenna
Subject: Re: Ignorant question: What's a G5RV???
Date: Tue, 02 Apr 1996 08:58:35 GMT
Distribution: world
Message-ID: <[e-mail]>
References: <4jnva4$[e-mail]>
Reply-To: [e-mail]

In message <4jnva4$[e-mail]> CHARLES J. MICHAELS wrote:

>
> Cecil said -
>
> Ya'll young sprouts only been licensed 32 years will just have to wait
> 8 more years. The Old, Old Timers Club, 3191 Darvany Dr., Dallas, TX
> 75220-1611 requires 40 years or more. We think the QCWA guys are still
> wet behind the ears. :-)
>
> Cecil,
>       I am QCWA and licensed since 1939.  Most of the QCWA guys I
> know think I am a young sprout.
>

Hmmm... for the benefit of one whose first look at Ham Radio was a
battered copy of the 1965 (ish) ARRL Handbook snatched from the back
of a Bulawayo refuse truck, (reading about Hiram Percy Maxim!)....
doooo tell what is QCWA?

G4WNT
--
Graham Seale


From [e-mail] Fri Apr 05 16:13:58 1996
From: [e-mail] (CHARLES J. MICHAELS)
Newsgroups: rec.radio.amateur.antenna
Subject: Re: Interference pattersn
Date: 1 Apr 1996 22:00:32 GMT
Message-ID: <4jpjm0$[e-mail]>


Question was asked -

Hello. CAn anyone suggest a program or algorithm to calculate
interference pattern of 2+ antennas given the infdividual patterns?
Thanks
[e-mail]


        The proximity of the antennas will cause the mutual impedance
between them to change the current distribution and hence the resulting
pattern will not be that of a simple interference of individual patterns.
        To precict the resulting patterns you must also specify the relative
phase of the current sin the individual antennas which in most cases will
be hanged by the mutual impedances.

Charlie, W7XC
--


From [e-mail] Fri Apr 05 16:13:59 1996
From: [e-mail] (WB3U)
Newsgroups: rec.radio.amateur.antenna
Subject: Re: Johnson Matchbox tuners
Date: Thu, 04 Apr 96 04:27:11 GMT
Message-ID: <4jvjh2$[e-mail]>
References: <[e-mail]> <4jrv1g$[e-mail]> <[e-mail]> <4ju6i1$[e-mail]> <4juhaq$[e-mail]>

   [e-mail] (WB3U) wrote:

>Even if the feedpoint presents so much capacitive reactance that it's
>nearly a direct short, the coil still won't resonate on 160M.

Sorry, this sentence in the previous post should read "capacitance",
not "capacitive reactance".

73,
Jack  WB3U


From [e-mail] Fri Apr 05 16:14:01 1996
From: [e-mail] (WB3U)
Newsgroups: rec.radio.amateur.antenna
Subject: Re: Johnson Matchbox tuners
Date: Wed, 03 Apr 96 18:43:38 GMT
Message-ID: <4juhaq$[e-mail]>
References: <[e-mail]> <4jrv1g$[e-mail]> <[e-mail]> <4ju6i1$[e-mail]>

   Cecil Moore <[e-mail]> wrote:

>Hi Carmine, here are a couple of ideas to give your balanced antenna
>tuner a little help on 160 meters:
>
>1. Make the antenna shorter than a halfwave so that the current
>maximum in the ladder-line occurs at the tuner, usually resulting in
an easy match.
>
>2. Same as number 1 except hang a parallel shorted stub less than 0.1
>wavelength back up the ladder-line from the tuner.

Hi Cecil,

I've been told that these methods can be used to help the Matchbox
tune 30M, but they won't work on 160M.

A link-coupled tuner needs to have sufficient L/C to resonate the
output coil at the frequency of operation.  This means that the
combination of the coil, the parallel and series capacitance in the
tuner and the reactive component of the feedline must combine to
create resonance.

In the Match Box, the series output capacitors limit the amount of
load capacitance that can be effectively placed across the coil.
These capacitors are 100 pf each.  Even if the feedpoint presents so
much capacitive reactance that it's nearly a direct short, the coil
still won't resonate on 160M.

This is why I decided to use a Match Box for now, but to also build my
own homebrew version.  The new tuner will use a homebrew coil with
approximately twice the inductance of the original.  Also, the
original design uses a variable cap across the coil, followed by the
two series variables, followed by another variable in parallel.  I'm
using identical capacitors from another Match Box in my homebrew
design, but I plan to rewire the circuit so the second parallel
capacitor is directly in parallel with the first (rather than being
separated by the series variables).

This will increase the maximum available parallel capacitance by about
70%, which in conjunction with doubling the coil will allow it to
resonate on 160M.  Also, the bandswitch will have two positions for
160M.  The second position will switch in fixed value 100 pf HV caps
across the series variables, in order to retain roughly the same
impedance tuning range as on the other bands.

I did run into a guy on the air awhile back who had modified his
Match Box for 160M by merely making the coil larger, but I question
the efficiency that results from this.  Even if the change in L/C
ratio doesn't have a negative effect, I think the input link will.
It's just too small for that band.

Incidentally, I haven't found an affordable source for the coil yet,
so I'm planning to build my own.  The windings will be about 14" in
length and 5" diameter, at 4 turns per inch.  A section at the center
about 2-1/2" long will be cut loose to provide an isolated input link.
I'll also be using a large variable from my old Dentron tuner in
series with the link, which should make the secondary tap positions
less critical.

I haven't decided whther to use the third wafer of my bandswitch to
adjust the turns of the link, or whether to use the spare Match Box
two-wafer rotary switch for this.  I'd like to have a minimum of
controls, but not if it sacrifices versatility.  The Match Box switch
would allow adjusting the link turns symmetrically, although I'm not
sure how important this is.  If it's not essential, the second wafer
of the Match Box switch could be used to insert a small fixed
capacitor in series with the link tuning capacitor on the higher
bands.  The Dentron capacitor is large enough for 160M, but I'm
concerned that it may provide optimum tuning on the higher bands.

Anyway, if the homebrew coil works out, I'll post the details of the
construction method.  On the other hand, if someone has a coil similar
to what I've described that they would like to sell . . .    :)

73,
Jack  WB3U


From [e-mail] Fri Apr 05 16:14:02 1996
From: Cecil Moore <[e-mail]>
Newsgroups: rec.radio.amateur.antenna
Subject: Re: Johnson Matchbox tuners
Date: 3 Apr 1996 15:47:13 GMT
Message-ID: <4ju6i1$[e-mail]>
References: <[e-mail]> <4jrv1g$[e-mail]> <[e-mail]>

"Carmine M. Iannace" <[e-mail]> wrote:
>Do you know of any modifications to get these units on 160 meters? I am also
looking for
>a schematic for them.

Hi Carmine, here are a couple of ideas to give your balanced antenna tuner
a little help on 160 meters:

1. Make the antenna shorter than a halfwave so that the current maximum
in the ladder-line occurs at the tuner, usually resulting in an easy
match.

2. Same as number 1 except hang a parallel shorted stub less than 0.1
wavelength back up the ladder-line from the tuner. This will result
in a resistive impedance equal to the characteristic impedance of
of the ladder-line, an easy match for a tuner. The distance from the
tuner and the length of the shorted stub will be approximately the
same.

73, Cecil, KG7BK, OOTC  (not speaking for my employer)





From [e-mail] Fri Apr 05 16:14:03 1996
From: Cecil Moore <[e-mail]>
Newsgroups: rec.radio.amateur.antenna
Subject: Re: Johnson Matchbox tuners
Date: 4 Apr 1996 02:27:13 GMT
Message-ID: <4jvc22$[e-mail]>
References: <[e-mail]> <4jrv1g$[e-mail]> <[e-mail]> <4ju6i1$[e-mail]> <4juhaq$[e-mail]>

[e-mail] (WB3U) wrote:
>A link-coupled tuner needs to have sufficient L/C to resonate the
>output coil at the frequency of operation.  This means that the
>combination of the coil, the parallel and series capacitance in the
>tuner and the reactive component of the feedline must combine to
>create resonance.
>
Sorry Jack, I was thinking 'T' type antenna tuner when I wrote that.
My fuzzy logic went: If a tuner can match 1000+j1000 on 80m, it
should be able to match 300 ohms on 160. Completely forgot about
the link.

73, cecil, kg7bk <==  feeling dumb...




From [e-mail] Fri Apr 05 16:14:06 1996
From: [e-mail]
Newsgroups: rec.radio.amateur.antenna
Subject: Re: Ladder line length
Date: Wed, 03 Apr 96 23:49:51 est
Message-ID: <[e-mail]>
References: <[e-mail]>


In Article<[e-mail]>, <[e-mail]> write:
> Path: interramp.com!interramp.com!psinntp!psinntp!gatech!newsfeed.internetmc
i.com!ns2.borg.com!usenet
> From: [e-mail] (Scott D. Souva)
> Newsgroups: rec.radio.amateur.antenna
> Subject: Ladder line length
> Date: Thu, 28 Mar 1996 13:54:33 GMT
> Organization: Borg
> Lines: 13
> Message-ID: <[e-mail]>
> NNTP-Posting-Host: l8.borg.com
> X-Newsreader: Forte Agent .99d/32.182
>
> I'm about to hang a 160 meter dipole and will use 450 ohm ladder line
> into an antenna tuner.  My question is-- how long should the feedline
> be?  I've got 100 feet of the stuff and would like to cut it to an
> optimal length.
>
> If I end up cutting the feedline to a specific length, how should the
> excess feedline be handled (coiled up...)?
>
> Any ideas would be welcome.
>
>
> Scott Souva
> [e-mail]
Scott:  I have just read your post and all the replies.
Put up your wire, either 135 feet or 270 feet as high as you can get it.
Make the feed line as long as you can, keep the 100 feet if possible.
Keep it a foot or so away from metal such as gutter and your tower.
My 450 ohm ladder line lies on the roof, then it is suspended on a piece of
pressure treated lumber to keep it away from the gutter, then it comes through

a hole I drilled inthe concrete block wall of my basement.
I feed it through a big old MFJ tuner.  With my 3 watt  qrp RIGS ON 80 AND 40,

I reliably work Europe and S America on CW.



From [e-mail] Fri Apr 05 16:14:07 1996
From: [e-mail] (W8JI  Tom)
Newsgroups: rec.radio.amateur.antenna
Subject: Re: Ladder line length
Date: 4 Apr 1996 12:07:02 -0500
Message-ID: <4k0vjm$[e-mail]>
References: <[e-mail]>

In article <[e-mail]>, Cecil Moore
<[e-mail]> writes:

>If you are using the balun in the MFJ for all-band operation,
>you are most likely losing a lot of power on some bands.
>Seems the conclusions reached here is not to use baluns
>unless they see a near resistive relatively low impedance.
>
>73, Cecil, KG7BK, OOTC
>
>

Unless it's a 1:1 choke balun, then it doesn't matter much.

4:1 baluns are the ones with impeance vs loss problems.

73 Tom


From [e-mail] Fri Apr 05 16:14:08 1996
From: [e-mail] (Graham Seale)
Newsgroups: rec.radio.amateur.antenna
Subject: Re: Ladderline to Rotatable - Results
Date: Tue, 02 Apr 1996 01:49:44 GMT
Distribution: world
Message-ID: <[e-mail]>
References: <4jfj0q$[e-mail]>
Reply-To: [e-mail]

In message <4jfj0q$[e-mail]> Doug Hall wrote:

> It tunes easily on 40, 30, and 17m. First QSO was with a 4O4 on 40m
> two hours before sunset, and he wasn't copyable on the vertical. That
> night on 40m I worked FR5, 3B8, GU, HK6, and HJ0. 30m QSOs so far
> include ZK, J5, 9U, 3B8, and 3DA0.  Nothing much on 17m  since it's
> usually dead in the evenings, but I've worked a couple of ZLs and VKs
> there. All with 100 watts.
>
> Needless to say, I'm pretty happy with the ladderline-fed rotatable
> dipole. The ladder line wrapping around the mast as it rotates doesn't
> seem to be a problem - the SWR only rises to about 1.2:1. 40m
> performance is much much better than with coax feed. The performance
> of my tribander wasn't affected, at least not that I could detect.

[with snips]

:-)  :-)  :-)

Hey Doug - we need some kind of symbol that expresses the appropriate
gesture that guys do together when it all goes right.

73's G4WNT

--
Graham Seale


From [e-mail] Fri Apr 05 16:14:09 1996
From: [e-mail] (Bill Howell)
Newsgroups: rec.radio.amateur.antenna
Subject: Re: Larson 2/70 open coil ant
Date: Tue, 02 Apr 1996 00:42:35 GMT
Message-ID: <4jpm9r$[e-mail]>
References: <4j92jd$[e-mail]>

My 2/70 resonates in-band. You might want to call Larsen back and
request a new stinger.
I had a problem with a 10-meter coil/mount, and they sent me a new
coil/mount. I returned the old one to them.

Tom Lewis <[e-mail]> wrote:

>FYI
>I recently purchased a Larson 2/70 dual band OPEN COIL antenna for my
>car.  When installed using the larson magmount, I discovered the antenna
>was resonant above both 2 meters and 70 centimeters!  The SWR was 2.2
>to one on the lower portion of the VHF band and 1.8 to one on the UHF.  I
>talked with a Larson representative on the phone.  He admitted there was
>a problem with the OPEN COIL stingers and the center frequency being
>above the ham bands!  He then suggested I purchase the closed coil
>antenna because it was tuned for the center of each band of interest.
>Anyway, I just wanted to share my experience with everyone.

>73!
>Tom Lewis - AB5CK
>AB5CK Dopplers
>Doppler technology - Radio Direction Finding





From [e-mail] Fri Apr 05 16:14:10 1996
From: [e-mail] (Scott Thompson)
Newsgroups: rec.radio.amateur.antenna
Subject: Luneberg Lens Antenna Manufacturers Search
Date: 2 Apr 1996 17:49:27 GMT
Message-ID: <4jrpb7$[e-mail]>

luneberg lens, manufacturers

Hello,

  I am looking for domestic (US) and foreign manufacturers of Luneberg
Lenses.  If anyone has any information, please let me know.  Thanks in
advance.

  Scott Thompson
  LJR, Inc.
  360 N. Sepulveda Blvd., Ste. 2030
  El Segundo, CA  90245  USA
  [phone]
  [phone] [Fax]
  [e-mail]      <<-<<< Notice: 3 t's




From [e-mail] Fri Apr 05 16:14:11 1996
From: [e-mail] (Louise Carkenord)
Newsgroups: rec.radio.amateur.antenna
Subject: metal box for tuner??
Date: 2 Apr 96 22:30:14 GMT
Message-ID: <[e-mail]>
Reply-To: [e-mail]



In the 1996 ARRL Handbook, page 22.60 is the following statement:

"Do not build your antenna tuner in a steel box! A steel enclosure
can raise a solenoidal coils losses sky high."

Is this advice correct??  Why have I never been cautioned about
this before??  Comments, please!!!

                                Lee Carkenord    KA0FPJ


From [e-mail] Fri Apr 05 16:14:12 1996
From: Cecil Moore <[e-mail]>
Newsgroups: rec.radio.amateur.antenna
Subject: Re: metal box for tuner??
Date: 3 Apr 1996 00:08:57 GMT
Message-ID: <4jsfip$[e-mail]>
References: <[e-mail]>

[e-mail] (Louise Carkenord) wrote:
>
>"Do not build your antenna tuner in a steel box! A steel enclosure
>can raise a solenoidal coils losses sky high."

Hi Lee, my MFJ949 works a lot better with the cover off. My present
balanced tuner is built into a plexiglas enclosure. One must be
careful about physical clearance of air-core coils in steel boxes.

73, Cecil, KG7BK, OOTC  (not speaking for my employer)




From [e-mail] Fri Apr 05 16:14:14 1996
From: [e-mail] (W8JI  Tom)
Newsgroups: rec.radio.amateur.antenna
Subject: Re: metal box for tuner??
Date: 3 Apr 1996 07:57:01 -0500
Message-ID: <4jtsit$[e-mail]>
References: <[e-mail]>

In article <[e-mail]>,
[e-mail] (Louise Carkenord) writes:

>In the 1996 ARRL Handbook, page 22.60 is the following statement:
>
>"Do not build your antenna tuner in a steel box! A steel enclosure
>can raise a solenoidal coils losses sky high."
>
>Is this advice correct??  Why have I never been cautioned about
>this before??  Comments, please!!!
>
>                               Lee Carkenord    KA0FPJ

Hi Lee,

That's not a good picture of the probelm. Losses are not much different
than they would be with an aluminum box, and in either case will be
insignificant with a good layout.

The steel doesn't have magnetic effects at radio frequencies, eddy
currents cancel the flux at the surface. It really boils down to the
amount of current flowing in the box, and the resistive losses of the box.


If you place the coils near an aluminum chassis, it also de-Q's the coil
and increases losses. In all cases the inductance drops, it's just like
adding a shorted turn to the coil. In all case coil Q and efficiency is
lowered.

If you place the coil too close to the chassis, losses will increase even
if the box is silver or gold! And they will increase nearly as much as if
the material was steel!

It's better to look at the problem as one of component location rather
than cabinet material.

Better advice would have been to keep the coils away from all metal, not
just steel.

73 Tom


From [e-mail] Fri Apr 05 16:14:14 1996
From: [e-mail] (WB3U)
Newsgroups: rec.radio.amateur.antenna
Subject: Re: metal box for tuner??
Date: Wed, 03 Apr 96 17:47:26 GMT
Message-ID: <4jue1c$[e-mail]>
References: <[e-mail]>

   [e-mail] (Louise Carkenord) wrote:

>In the 1996 ARRL Handbook, page 22.60 is the following statement:
>
>"Do not build your antenna tuner in a steel box! A steel enclosure
>can raise a solenoidal coils losses sky high."
>
>Is this advice correct??  Why have I never been cautioned about
>this before??  Comments, please!!!
>
>                               Lee Carkenord    KA0FPJ

Wish I'd known this before I bought a Dentron tuner.  Omigosh, I just
realized my HF amplifier is in a steel cabinet too!  Yikes, so's my
transceiver!  This is worse than Mad Cow disease!  ;)

73,
Jack  WB3U


From [e-mail] Fri Apr 05 16:14:16 1996
From: [e-mail] (Forwarded Message)
Newsgroups: rec.radio.amateur.antenna
Subject: Re: metal box for tuner??
Date: Wed, 03 Apr 96 21:57:46 GMT
Message-ID: <4jusml$[e-mail]>
References: <[e-mail]> <4jue1c$[e-mail]>

The following message was received in e-mail and is being posted at
the request of the author.  Please refer any comments only to the
e-mail address shown at the end of the message.  73,  Jack  WB3U

Forwarded Message Follows:

  Placing a linear coil next to any metal surface could add capacitance
resulting in possible lowered resonant frequency of the coil, and
degraded unloaded-Q, but this effect is usually not so great.  Of larger
concern is if there are toroidal coils in the antenna tuner.  In this
case, be sure that a metal screw is NOT used to fasten the toroid to a
metal box on two surfaces.  Doing so would cause a SHORTED TURN around the
toroid/  The screw passing through the center of the toroid, then the metal
box forming the rest of the turn.  This shorted turn would enclose the
magnetic path of the torioid resulting in a drastic lowering of the
Q of the coil and very detrimental effects on the performance.  Whether
the material is aluminum or steel in this case is not important as the
shorted turn is worsened by the low electrical resistance (not by
the magnetic reluctance).


                                                - Tom McDermott, N5EG

------------------------------------------------+-----------------------------
 Tom McDermott                                  | "All opinions expressed
 Alcatel Network Systems, Inc.                  | are my own, and do not
 [e-mail]                       | represent those of Alcatel
   [ ICC'96 Technical Program Secretary ]       | Network Systems, Inc."
   [   June 23-27, 1996, Dallas, Tx.    ]       |
------------------------------------------------+-----------------------------




From [e-mail] Fri Apr 05 16:14:17 1996
From: [e-mail] (Tom Bruhns)
Newsgroups: rec.radio.amateur.antenna
Subject: Re: metal box for tuner??
Date: 4 Apr 1996 01:07:32 GMT
Message-ID: <4jv7ck$[e-mail]>
References: <4jtsit$[e-mail]>

W8JI  Tom ([e-mail]) wrote:

(about coils near enclosures...)

: Better advice would have been to keep the coils away from all metal, not
: just steel.

First, let me make it clear that I agree with Tom's advice.  Just wanted to
add that there are things you can do about it...

A few years ago, I worked in a group that built, as part of a larger
system, a 1.00MHz power amplifier.  It was actually rather low power,
driving an essentially purely capacitive load, but needing to drive the
50pF or so up to a few thousand volts.  To keep the power low, and also
to keep distortion on the 1MHz output low, it was important that the
tank Q be as high as possible for the space allowed for the
amplifier/tank.  The group had been building these things for some time,
and had refined the design quite a bit; the tank coils were Litz wire
wound in a particular way, only just over 1 inch diameter.  If they were
operated in an open environment (enclosure reasonably far away), the
tank Q could be up in the 300 region, not bad for such small coils at
1MHz.  But for this particular project, we needed to make the enclosure
smaller.  The designer meticulously mapped the magnetic field vectors at
the surface around the coils where we were proposing to put sheet metal,
and then had slots cut in the metal at all sorts of wierd angles, to
break up the currents.  He was able to achieve a much higher Q that way
than with solid sheet metal in the same place.  I always wondered how
much affect it had on external fields--after all, the whole purpose of
the sheet metal was to keep the thing from radiating all over the place.
But it was never a problem.  -- I think this technique falls in the
category of "don't try this at home, kids."

--
Cheers,
Tom
[e-mail]


From [e-mail] Fri Apr 05 16:14:18 1996
From: [e-mail] (WB3U)
Newsgroups: rec.radio.amateur.antenna
Subject: Re: metal box for tuner??
Date: Wed, 03 Apr 96 18:40:27 GMT
Message-ID: <4juh4o$[e-mail]>
References: <[e-mail]> <4jtsit$[e-mail]>

Post / CC by Mail

   [e-mail] (W8JI  Tom) wrote:

>If you place the coils near an aluminum chassis, it also de-Q's the
>coil and increases losses. In all cases the inductance drops, it's
>just like adding a shorted turn to the coil. In all case coil Q and
>efficiency is lowered.

Hi Tom,

How does this relate to a bandswitched coil in which turns are
progressivly shorted in order to tune higher frequencies?  The 160-10M
tuner I'm building will use that method, and on the higher bands, the
ratio of shorted to active turns becomes pretty large.  Is this likely
to have a significant impact on the efficiency (Q) of the coil?

73,
Jack  WB3U


From [e-mail] Fri Apr 05 16:14:19 1996
From: [e-mail] (W8JI  Tom)
Newsgroups: rec.radio.amateur.antenna
Subject: Re: metal box for tuner??
Date: 4 Apr 1996 08:03:33 -0500
Message-ID: <4k0hb5$[e-mail]>
References: <4jv7ck$[e-mail]>

In article <4jv7ck$[e-mail]>, [e-mail] (Tom Bruhns)
writes:

>
>: Better advice would have been to keep the coils away from all metal,
not
>: just steel.
>
>First, let me make it clear that I agree with Tom's advice.  Just wanted
to
>add that there are things you can do about it...
>
>

Hi Tom, Actually I never said how far away. A couple of coil diameters is
enough, the end spacing is the most critical. Never jam the end of the
coil up against the sheet metal, even if it's silver.

In measurements here, I've found the optimum L/D of a coil in free-air
varies from 1:1 to 4:1 and I've found Q's as high as the mid 300's. Bigger
hasn't always been better for the coil.

73 Tom


From [e-mail] Fri Apr 05 16:14:20 1996
From: Will Flor <[e-mail]>
Newsgroups: rec.radio.amateur.antenna
Subject: Re: Need Guidlines for F.S. Tower Bases
Date: 4 Apr 1996 20:36:14 GMT
Message-ID: <4k1bru$[e-mail]>
References: <4jhcl7$[e-mail]> <4k12ig$[e-mail]>

KF5KF (Robert Redoutey) wrote:
>In article <4jhcl7$[e-mail]>, David Nulton <[e-mail]> says
:
>>
>>A friend of mine has a free standing tower and needs some info on
>>how to make the base for it.  We have two problems here.
>>
>>1.  How big should the base be.  (i.e.  should the mass of the
>>concrete equal or be more than the mass of the tower?
>>
>>2.  In central Texas the soil has alot of limestone in it.
>
>I too live in Central TX and have rented an electric jack hammer with
>excellent success. I would go down at least 4-5 ft and 4 ft square. Alot
>depends on the tower. Its not all that bad, really. Just take your time
>and find a few friends to help. I have a Rohn HDBX style and am down over
>4' and 4' across. Took a full day to do it. After 3 ft of rock, it was
>nice black soil!
>

I'm pretty sure the Uniform Building Code has a chapter in it concerning
antenna support structures; you should find this in a library and make
sure you follow any guidelines you find there.  They should have very
specific guidelines covering foundations there.

73 de Will KB9JTT        [e-mail]




From [e-mail] Fri Apr 05 16:14:21 1996
From: Ron Thompson <[e-mail]>
Newsgroups: rec.radio.amateur.antenna
Subject: Need help with high SWR problem
Date: 5 Apr 1996 15:17:52 GMT
Message-ID: <4k3dj0$5mg@lambchop>

I have a mobile 2M 50W radio I am using as a base rig.
It runs off of a 20A power supply, and feeds a 75 foot
piece of RG-213 connected to a Cushman Ringo Ranger II
7db gain antenna.

When I adjusted the tuning rod, my SWR meter was hooked
up near the radio.  I got the SWR down to 1.1:1, but the
indicated forward RF power was 120 Watts.  This radio
only puts out 50 Watts.

In use, the radio can recieve another 50W radio, but
cannot transmit to it very far.  This indicates to me
that all the power is not getting out.

I then moved the SWR meter to the antenna end of the
feedline, and took another reading.  The SWR was
over 8:1, and the indicated RF power was about 50 Watts.

I unscrewed the shield from the feedline on receive to
see if there was a short, but the signal dropped.  I
also used a multimeter to check for a short between the
shield and the center wire, and it is OK.

This is the second antenna I have tried, since I thought
something was wrong with the first one.  Same thing
with both antennas, so I can rule that out.

I'm stumped.  HELP!

Please e-mail reply as well as posting.

KE6AGC
Ron Thompson
[e-mail]



From [e-mail] Fri Apr 05 16:14:23 1996
From: Chris Boone <[e-mail]>
Newsgroups: rec.radio.amateur.antenna
Subject: Re: no tune antenna
Date: 2 Apr 1996 23:05:54 GMT
Message-ID: <4jsbsi$[e-mail]>
References: <4j8sf1$[e-mail]>

[e-mail] wrote:
>can anyone give me info on a no tune antenna for 80-10m.
>I have a problem with my tuner on my present antenna cut for 3700 khz.
>Thanks
>KD4DPB
>Billy

Actually there are a few such antennas but the ones within amateur
pricing is the B&W series...

The AC3.5-30 and AC1.8-30 cover the HF bands with low SWR BUT they are
NOT efficient radiators.

They have a "matching network" at the top of the folded dipole which is
nothing more than a 600 ohm resistor non inductive...

The balun is a 16:1...which takes a 50ohm cable and goes to 900 ohms...so
the antenna can swing from 450 to 1800 ohms and stay within a 2:1 match!
With the 600ohm resistor load, the antenna stays fairly well in that
range yet it losses some radiation eff in the load (as much as 6-10db on
80 and 40 from what I have read)


I agree with the gentleman who said use a skyhook! I have a 80mtr
fullwave loop up right now....works great on 80-15 so far...havent tried
it on 10 and the SWR is worst on 40mtr (only 3:1)...

Look at the antenna handbooks, etc for the FULLWAVE loop and try it..

73
Chris
WB5ITT



From [e-mail] Fri Apr 05 16:14:24 1996
From: [e-mail] (Bob Levine)
Newsgroups: rec.radio.amateur.antenna
Subject: Opinion Pse Force C4XL
Date: 4 Apr 1996 19:40:33 GMT
Message-ID: <4k18jh$[e-mail]>
Reply-To: [e-mail]

Looking for users of the Force C4XL antenna. It's a tribander
with 2 el on 40.  I would put it @60' level of a house bracketed
tower.  Performance, SWR, durability of those teeny tapered
(to 3/8") elements.

Also, what's the deal with requiring 100' of coax.  I will have
that much, but I dont understand why the SWR at the antenna is
high on the band edges if measured at the antenna.  The lit says
the antenna was DESIGNED to be used with 100' of coax.



--
/*****************************************************************
 *      Bob Levine                                               *
 *      Manager of Application Engineering                       *
 *      Mercury Computer Systems             KD1GG/VK2GYN/7J1AIS *
 *  For info about jobs at Mercury Computer Sys, pls reply to me  *
 *****************************************************************/




From [e-mail] Fri Apr 05 16:14:24 1996
From: [e-mail] (WB3U)
Newsgroups: rec.radio.amateur.antenna
Subject: Re: Propagation Query
Date: Mon, 01 Apr 96 17:43:47 GMT
Message-ID: <4jp51s$[e-mail]>
References: <4jnrmf$[e-mail]> <4jook0$[e-mail]>

   [e-mail] (W8JI  Tom) wrote:

> I'm able to work VK longpath with my 40 meter mobile, and Russians
>all night long.

Same here.  Sometimes I abandon 80M because of the atmospheric noise,
but then I can't raise a CW ragchew on 40M to save my life.  There are
just too dern many of those pesky DX stations!  ;)

73,
Jack  WB3U


From [e-mail] Fri Apr 05 16:14:26 1996
From: [e-mail] (Gary Schwartz)
Newsgroups: rec.radio.amateur.antenna
Subject: Re: Propagation Query
Date: 2 Apr 1996 05:33:59 GMT
Message-ID: <4jqe87$[e-mail]>
References: <4jnrmf$[e-mail]> <4jook0$[e-mail]> <4jp51s$[e-mail]>

WB3U ([e-mail]) wrote:
:    [e-mail] (W8JI  Tom) wrote:

: > I'm able to work VK longpath with my 40 meter mobile, and Russians
: >all night long.

: Same here.  Sometimes I abandon 80M because of the atmospheric noise,
: but then I can't raise a CW ragchew on 40M to save my life.  There are
: just too dern many of those pesky DX stations!  ;)

: 73,
: Jack  WB3U

Boy, sure wish I had YOUR problems! :)

--
73,
Gary K9GS
   __________________
  /       K9GS       |______________________________
 /   FP/K9GS, TO5M   |Society of Midwest Contesters |____________________
(                    |   [e-mail]   |Secretary/Treasurer/
 \   Gary Schwartz   |   [e-mail]    | Greater Milwaukee/
  \__________________|     PacketCluster: NB9C      |  DX Association (
                   (________________________________|       GMDXA      \
                                                  (_____________________\



From [e-mail] Fri Apr 05 16:14:27 1996
From: [e-mail] (Gary Schwartz)
Newsgroups: rec.radio.amateur.antenna
Subject: Re: Propagation Query
Date: 1 Apr 1996 06:05:03 GMT
Message-ID: <4jnrmf$[e-mail]>
References: <4jmj0i$[e-mail]> <4jms94$[e-mail]>

W8JI  Tom ([e-mail]) wrote:
: In article <4jmj0i$[e-mail]>, David Nulton <[e-mail]>
: writes:

: >Solar activity should start to increase in 97 and be much better
: >by 99.  The bands are still worth using, and you can work good DX.
: > However, you will have to look harder than you did 5 years ago.
: >
: >73s de KI5XW
: >
: >

: 160, 80 and 40 have poorer propagation as sunspots increase. DX is better
: on those bands at the minimum.

I have to disagree here, at least in part.  At this point in the solar
cycle, 40M propagation is pretty poor except right at sunrise and sunset.
Late at night the MUF has been going below 7 Mhz most of the time,
resulting in pretty poor propagation.

All too often in texts I see 40M lumped in with the "low bands"(160 and
80M) and the statement that 40M improves with a declining sunspot
activity.  This is just not the case.  It is my experience that 40M is
best on either side of the peak.  Generally when the solar flux is
110-130.  I fondly remember easily working Europe from WI at night with
100W and low dipoles/verticals all night long several years ago.  Now that is
only possible for a few hours at my sunset and with reduced signal strengths.


: If you like the lowest HF bands, you'll have to look harder as sunspots
: increase.


Some might debate this as well, but I won't.  There was a thread on the
top-band reflector several days ago that touched on this.

--
73,
Gary K9GS
   __________________
  /       K9GS       |______________________________
 /   FP/K9GS, TO5M   |Society of Midwest Contesters |____________________
(                    |   [e-mail]   |Secretary/Treasurer/
 \   Gary Schwartz   |   [e-mail]    | Greater Milwaukee/
  \__________________|     PacketCluster: NB9C      |  DX Association (
                   (________________________________|       GMDXA      \
                                                  (_____________________\



From [e-mail] Fri Apr 05 16:14:29 1996
From: Phil Keller <[e-mail]>
Newsgroups: rec.radio.swap,rec.radio.amateur.antenna,rec.radio.amateur.digital.misc,rec.radio.amateur.equipment,rec.radio.amateur.homebrew,rec.radio.amateur.misc,rec.radio.amateur.policy,rec.radio.amateur.space,rec.radio.noncomm,rec.radio.scanner,rec.radio.shortwave,rec.radio.swap
Subject: Re: Shortwave etc database program....
Date: Tue, 02 Apr 1996 16:33:50 -0800
Message-ID: <[e-mail]>
References: <[e-mail]>

And the Cost is ????

-Phil-

Charles Bolland wrote:
>
> Sir,
>
> A stand alone IBM compatible Broadcasting Radio Station Database
> program for Longwave, Mediumwave, or Shortwave.  4000 records...
> Completely read/write and updateable...
>
> If you'd like a copy, send your EMail address and Postal Address
> which will be used to pass you more detailed information on
> the full featured program....
>
> The above program will be sent via EMAIL...
>
> All information will be kept confidential....
>
> Chuck
>
> KA4PRF

--
====================================
"Those who avoid decapitation,
              leave more offspring."
    -Carl Sagan-
====================================
Phil Keller                    N6MWC
mailto:[e-mail]


From [e-mail] Fri Apr 05 16:14:30 1996
From: [e-mail] (Douglas R Davis)
Newsgroups: rec.radio.amateur.antenna
Subject: Simple 2 Meter Gone Wrong
Date: 3 Apr 96 16:51:21 GMT
Message-ID: <[e-mail]>

I used a 40" section of #14 stranded wire w/insulation, stripped 2" of
insulation from each end and made a couple of loops (the outcome was 38"
long, looptip to looptip).
I soldered the loops, then cut out a one inch section of insulation in
the exact center of the wire (I wanted the antenna to be resonant at
147.585).
I used a 9' section of RG-58U with a PL-259 on one end, and soldered both
the braid & center conductor to the wire; the solder points are about
1/2" apart.

I can't receive & I can't transmit (using the Alinco DR-150T). When I
hook up to my Antron 99 I can receive & transmit over the local repeater
OK. (I only tried it once because I don't imagine the match is very
good).
Oh yes, I hung the 38" antenna up in the corner of my room (vertically)
stretched between two push pins. I'm on the second floor probably about
25' up.

What am I doing wrong? Should I be mad at the wire? ;-)

Thanks,
Doug
KC8CGX


From [e-mail] Fri Apr 05 16:14:31 1996
From: VE4KLM <[e-mail]>
Newsgroups: rec.radio.amateur.antenna
Subject: Re: Simple 2 Meter Gone Wrong
Date: Thu, 4 Apr 1996 09:42:03 -0600
Message-ID: <[e-mail]>
References: <[e-mail]>


On 3 Apr 1996, Douglas R Davis wrote:

> I used a 40" section of #14 stranded wire w/insulation, stripped 2" of
> insulation from each end and made a couple of loops (the outcome was 38"
> long, looptip to looptip).
> I soldered the loops, then cut out a one inch section of insulation in
> the exact center of the wire (I wanted the antenna to be resonant at
> 147.585).
> I used a 9' section of RG-58U with a PL-259 on one end, and soldered both
> the braid & center conductor to the wire; the solder points are about
> 1/2" apart.

Hi Doug,

I hope I am not being setup for an April Fools's joke, but my first question
is why the heck are the 2 'poles' connected at the center. I would suggest
you cut out more than just 1 inch of insulation. Try cutting out 1 inch of
the entire wire instead. Of course you will have to use a piece of plastic
or plexiglass to support your 1/2 wave dipole at the center now. The braid
of the coax will go the one of the 'poles', and the center conductor will
go to the other 'pole'. The 'poles' are not connected together.

At the same time, I realize that maybe you are trying to do some type of
delta matching, but that is something I have never tried myself, so I can
not comment on that. Check the ARRL handbook.

Regards and good luck.

Maiko Langelaar
VE4KLM, Winnipeg

 ---------------------
|  SLM Software Inc.  |
| [e-mail] |
 ---------------------



From [e-mail] Fri Apr 05 16:14:32 1996
From: Zack Lau <[e-mail]>
Newsgroups: rec.radio.amateur.antenna
Subject: Re: Simple 2 Meter Gone Wrong
Date: Thu, 04 Apr 1996 09:33:34 -0500
Message-ID: <[e-mail]>
References: <[e-mail]>
To: Douglas R Davis <[e-mail]>

Douglas R Davis wrote:
>
> I used a 40" section of #14 stranded wire w/insulation, stripped 2" of
> insulation from each end and made a couple of loops (the outcome was 38"
> long, looptip to looptip).
> I soldered the loops, then cut out a one inch section of insulation in
> the exact center of the wire (I wanted the antenna to be resonant at
> 147.585).
> I used a 9' section of RG-58U with a PL-259 on one end, and soldered both
> the braid & center conductor to the wire; the solder points are about
> 1/2" apart.
>
> I can't receive & I can't transmit (using the Alinco DR-150T). When I
> hook up to my Antron 99 I can receive & transmit over the local repeater
> OK. (I only tried it once because I don't imagine the match is very
> good).
> Oh yes, I hung the 38" antenna up in the corner of my room (vertically)
> stretched between two push pins. I'm on the second floor probably about
> 25' up.
>
> What am I doing wrong? Should I be mad at the wire? ;-)

Did you actually cut the wire in half, or is there half
an inch of wire between the center pin and the braid?

The most common error is an improperly installed PL-259
connector.  Check it with an ohmmeter to make sure there
aren't any unexpected shorts or opens.

You might want to consider the groundplane antenna on page
20.58 of the 1996 ARRL Handbook.  There are step by step
instructions and photos to aid the beginner.

Zack KH6CP/1



>
> Thanks,
> Doug
> KC8CGX


From [e-mail] Fri Apr 05 16:14:33 1996
From: [e-mail] (John Derry)
Newsgroups: rec.radio.amateur.antenna
Subject: Socalled RG-8X
Date: 3 Apr 1996 21:21:22 GMT
Message-ID: <4juq4j$[e-mail]>

Don't use RG-8X, sometimes reffered to as RG-8M, for 2 meters or 0.7
meters if you can help it.  I overheard some hams talking and one of them
said he was replacing his RG-8 with NEW RG-8X.

Bad idea.  Too darned lossy.  Eh?

Of ourse I guess it's OK to use any kind of cable as long as you use gold
plated connectors.  :-)

73 de Jack, K9CUN


From [e-mail] Fri Apr 05 16:14:34 1996
From: [e-mail] (Joe Leikhim)
Newsgroups: rec.radio.amateur.antenna
Subject: Stoddard 1.0 - 2.0 GHz Calibration Horn antenna for sale
Date: Wed, 03 Apr 1996 22:31:56 GMT
Message-ID: <4juupe$[e-mail]>

This is a laboratory grade horn antennna approx 12 db gain. In
excellent condition. $250 plus shipping

Joe at

[e-mail]



From [e-mail] Fri Apr 05 16:14:35 1996
From: Zack Lau <[e-mail]>
Newsgroups: rec.radio.amateur.antenna
Subject: Re: Sturba Curtain
Date: Mon, 01 Apr 1996 10:04:25 -0500
Message-ID: <[e-mail]>
References: <4j967g$7ig$[e-mail]> <4j9ntn$[e-mail]> <[e-mail]> <[e-mail]>
To: Rick Rikoski <[e-mail]>

Rick Rikoski wrote:
>
> Zack wrote:
>
> > Rick, true diversity reception requires a method of switching out
> > the unwanted antennas--this is usually done with separate receivers
> > to monitor the reception on each antenna.
> ============================================================================
===
> This is a relatively modern twist. Diversity reception was well known
> before the onset of smart receivers and microprocessors.

I suppose in geological terms the 1930s are modern.  However, work
by H.H. Beverage used separate receivers without the benefit of
microprocessors.  See the April 1931 IRE Proceedings, p 531-535...

Zack KH6CP/1.


From [e-mail] Fri Apr 05 16:14:37 1996
From: [e-mail] (W8JI  Tom)
Newsgroups: rec.radio.amateur.antenna
Subject: Re: Sturba Curtain
Date: 1 Apr 1996 09:18:23 -0500
Message-ID: <4joojf$[e-mail]>
References: <[e-mail]>

Hi Rick,
In article <[e-mail]>, [e-mail]
(Rick Rikoski) writes:

>==============
>This is a relatively modern twist. Diversity reception was well known
>before the onset of smart receivers and microprocessors.

That's right. They used DUAL receivers and combined in the audio.

>What you call "true" diversity reception, I would call "optimized"
>diversity reception.

>Without a pair of smart receivers capable of making judgements to go with
>the antenna getting the best signal at each instant one can still get
>diversity reception by connecting two or more antennas together.

Not at all. It causes fading as much as it reduces it. Adding more random
phase and amplitude signals at one point by a fixed combiner can not
reduce fading.

>The antenna getting a signal will contribute the signal while the others
>will not.

And when they ALL "get signals" they will subtract or add randomly. The
signals will just as likely to subtract as add.


>> Otherwise, how do you
>> prevent signal cancellation?
>Is this system optimal? Definitely not. The other antennas will
contribute
>noise and may add out of phase components. But on average, a system of
two
>or more antennas will give more reliable reception than just one antenna.

Only if GAIN or directivity in the predominate path increases by the
addition. It has nothing to do with "diversity" or "frontal area" of the
array.

73 Tom


From [e-mail] Fri Apr 05 16:14:38 1996
From: [e-mail] (Russ LeBlanc)
Newsgroups: rec.radio.amateur.antenna
Subject: Re: T2FD
Date: 1 Apr 1996 16:58:15 GMT
Message-ID: <4jp1v7$[e-mail]>
References: <4gnorv$[e-mail]>

In article <4gnorv$[e-mail]>, [e-mail] says...
>
>Does anyone have a list of references for the Tilted Terminated Folded
>Dipole?  I've built a couple but am looking for some more refs.  Jim

Guy Atkins wrote a good article on this antenna in the 1990 issue of
Fine Tuning's Proceedings (T2FD - The Forgotten Antenna).  Some refs he
included are:


Performance of the Terminated Folded Dipole, CL Countryman, Nov 1951 QST

More on the T2FD, CL Countryman, Feb 1953 QST

A Little Gem for QRM, May 1984 73 Magazine

World Radio Television Handbook, 1988 & 1989, Billboard Pubs.

World Radio Television Handbook Equipment Buyer's Guide (1993 I believe)



Some of the SWL clubs might have reprints available on this topic.

Hope this helps,

Russ



From [e-mail] Fri Apr 05 16:14:40 1996
From: [e-mail] (K5HWH)
Newsgroups: rec.radio.amateur.antenna
Subject: Re: The Free-Space Antenna
Date: 1 Apr 1996 18:05:09 -0500
Message-ID: <4jpnf5$[e-mail]>
References: <4joc0a$[e-mail]>

W7EL (a Guru) writes:
> "An antenna," they said, "is simply a means to match a
>transmission line to free space."

>Say goodbye to lossy antennas and feedline matching problems. Try the
free-
>space antenna today!

     Better yet, why not design the final in your rig for 377 ohms output
and feed free space directly from the transmitter? Forget about feed
lines, baluns antennas and all the related problems. Very clever article.
I thoroughly enjoyed it.

K5HWH
e-mail to [e-mail]



From [e-mail] Fri Apr 05 16:14:42 1996
From: Chris Boone <[e-mail]>
Newsgroups: rec.radio.amateur.antenna
Subject: Re: Wich 6m antenna to choose ??
Date: 3 Apr 1996 19:07:52 GMT
Message-ID: <4juia8$[e-mail]>
References: <4jpqne$[e-mail]>
To: [e-mail]

[e-mail] (Martin Rask) wrote:
>Hello all...
>
>Thanks for reading this..
>
>Ißm just going to buy a 6M antenna my biggest problem is just wich one do
>i choose ??
>
>We are only allowed to use 200W ERP here in sweden so the antennas won┤t
>have to stand much power HIHI.. but i hope they will change the power
>amount soon..
>
>Here is some antennas that i have been thinking of
>
>CREATE CL6DX 7el
>
>M2 6M7 7el
>
>CUSHCRAFT A50-6S 6el
>
>CUSHCRAFT A50-5S 5el
>
>CUSHCRAFT 617-6B 6el
>
>I have never worked on 6m so i would really like to know something about
>these antennas.. how do they work ?? are they easy to put togeher ?? do
>the stand wind and snow ?? and other things ?? have you tried any other
>antenna that is better ??
>
>I┤am really looking forward for some answers..
>
>73┤s de SM7VHS /Martin
>
>my email: [e-mail]
>
Martin, for SSB/CW work, the A50 models will do just fine....they cover
about 1 Mhz of bandwidth and have average gain (around 10db)....They are
gamma matched with grounded boom and elements (as most Cushcraft yagis
are) and are easy to install...

I am using a commercial version at work on 48 Mhz and have had no
problems with it in 6+ years its been up....(using it in vertical FM
mode on top of 150ft tower)

As for the others, if you like their price, then go for them.....just
about any 6mtr yagi on the market is decent....just compare gain factors
and price.....(and maybe material but most are good quality)


73
Chris
WB5ITT



From [e-mail] Fri Apr 05 16:14:42 1996
Newsgroups: rec.radio.amateur.antenna
Subject: WTB   --   B & W  DIPOLE  CENTER  INSULATOR  <<  Mod  CC-50  >>
Message-ID: <[e-mail]>
From: Bill <[e-mail]>
Date: 3 Apr 96 09:26:14 CST



Looking for Barker & Williamson CC-50 center insulator
for doublet antenna.

73s

Bill Worthington
AA4FM/0
Eudora, Kansas, USA



From [e-mail] Fri Apr 05 16:14:44 1996
Newsgroups: rec.radio.amateur.antenna
From: Ron Lile <[e-mail]>
Subject: Re: yagi antenna help!!
Message-ID: <[e-mail]>
References:  <4jlrmi$[e-mail]>
Date: Mon, 1 Apr 1996 16:16:10 GMT

[e-mail] (Rob Cheply) wrote:
>
> HI i was wondering if anyone knows if there is somewhere I can
> download a diagram of a Yagi antenna with all the lengths of the
> peices for the 143 - 144 Mhz range. If so please tell me
> Thanx
>
> Cory Cheply
> [e-mail]
 Rob;

This frequency range is quite close to the 144 MHertz lower limit of the amate
ur band a very simple way to get the dimensions you seek is to use any of the
VHF or antenna handbooks and then apply the ratio of the design frequency of t
he handbook antenna and the desired frequency you wish to receive/tranmsit on.

This ratio will look like: ratio = f(desired)/f( design in handbook). Using th
is ratio times the element deminsions will get you very close to an adequate d
esign at the new frequency.

Ron K0RL

[e-mail]


From [e-mail] Tue Apr 09 16:59:34 1996
From: [e-mail] (WB3U)
Newsgroups: rec.radio.amateur.antenna
Subject: Re: "floating" the output of a tuner.
Date: Wed, 03 Apr 96 22:09:16 GMT
Message-ID: <4jutc5$[e-mail]>
References: <[e-mail]> <4jtqn7$[e-mail]> <[e-mail]>

   Cecil Moore <[e-mail]> wrote:
>W8JI  Tom <[e-mail]> writes:

>>radiating like a Harley leaks oil!
>
>Hey Buddy, you can insult me or my antenna but flaming my Harley
>is stepping over the line!

I don't think it was an insult Cecil.  Leaving your mark when you park
a Harley lets other drivers know who owns that parking spot.  If my
last one hadn't leaked, I would've drilled a hole in the crankcase. ;)

73,
Jack  WB3U


From [e-mail] Tue Apr 09 16:59:35 1996
From: [e-mail] (Zacharias Liangas)
Newsgroups: rec.radio.amateur.antenna
Subject: 2-loop antenna questions
Date: Mon, 08 Apr 1996 12:41:07 GMT
Distribution: world
Message-ID: <4kb170$[e-mail]>
Reply-To: [e-mail]

dear friends of the list
this time i am intending to make an  2-loop antenna for two different
bands namely 30 and 60 m (SW use only ) , qhich as per my opinion
vould be nice to be included in one mast together so that the 30 mb
tobe co-centeresd with the other of 60 mb
As per theory the 30mb can be 1.1 m per side and 2.2 m for the 60m
They will mainly be used fo local noise cancelling
and instead of using variable capacitor to use varactor  so that I can
remotely yune them

Thi is my idea at all. What is your opinion . Can  both operate well
or the one can effect the other?

TIA

Zakaria Liang!
(namanya untuk kawan sahaja!)



From [e-mail] Tue Apr 09 16:59:36 1996
From: [e-mail] (WA6UBE)
Newsgroups: rec.radio.amateur.antenna
Subject: 40/80/160 meter G-Tor via NVIS antennas
Date: 5 Apr 1996 15:39:45 -0500
Message-ID: <4k40eh$[e-mail]>
Reply-To: [e-mail] (WA6UBE)

I will be setting up a portable HF data station on April 18th, and 19th to
test
a military HF radio and antenna system.  This will be a field test with
generator
and back-up battery power.

If you have an HF data station capable of G-tor and are within a 400 mile
radius of the Modesto/Waterford california area, I would like to hear from
you!!

My station will consist of a Sunair model GSB900DX military hf ssb
transceiver
hooked to a military NVIS antenna system model AS2259/GR. The antenna
has also been modified to allow better performance in the frequency range
of
1.6 to 4.0 mhz.  The TNC is a Kantronics Kam+ and the PC will be an Grid
Systems 486 series laptop pc.

I plan to have a mailbox set up on 80 meters and have the station set up
in an
un-attended mode to allow people to connect and leave messages.

If you are interested in testing NVIS with me, please send me an e-mail

Sincerely

Patricia Gibbons / <[e-mail]>
"The Vertical Skywave Girl"

[e-mail] "The Vertical Skywave Girl" ...
Mobile repair shop supervisor - City of San Jose/ GSA-Communications
voice-mail: 1-408-277-4082
PGP Public key available on request


From [e-mail] Tue Apr 09 16:59:37 1996
From: [e-mail] (WB3U)
Newsgroups: rec.radio.amateur.antenna
Subject: Re: 40M Dipole or Vertical ?
Date: Tue, 09 Apr 96 17:47:51 GMT
Message-ID: <4kefco$[e-mail]>
References: <[e-mail]>

Post / CC by Mail

   [e-mail] (Don Payne) wrote:

>Are the new hi-tech multi band verts worthwhile?

It depends on what you need the antenna to do.  The problem with these
designs on 40M is that the radial system isn't terribly effective.
Also, from what I hear, the traps/coils/stubs tend to be lossy, and
except for maybe the R7, mechanical construction leaves something to
be desired.

If you're only interested in 40M, it would be much cheaper and more
effective to put up an aluminum pole at ground level and install lots
of radials.  Add a matching network at the base, designed specifically
for 40M, and you'll have a pretty efficient system.

Of course, this all assumes you really want a vertical and that noise
isn't a problem at your QTH.

73,
Jack  WB3U


From [e-mail] Tue Apr 09 16:59:38 1996
Newsgroups: rec.radio.amateur.antenna
From: [e-mail]
Subject: <<HELP WITH PHASING HARNESS PLEASE>>
Message-ID: <[e-mail]>
Date: Wed, 3 Apr 1996 12:43:54 GMT

Hi there,
         Can someone help with a phasing harness to co-phase to 16 element
beam antennas that operate on the 477mhz in Australia.  These antennas are
for Ciziten Band in Australia and all we need is what type of cable is
required to use, (75OHMS) and what the measurements of the harness is.

[e-mail]


From [e-mail] Tue Apr 09 16:59:39 1996
From: [e-mail] (Roy Lewallen)
Newsgroups: rec.radio.amateur.antenna
Subject: Re: A 2-cent antenna for 2-mtrs
Date: Sat, 06 Apr 96 01:27:07 GMT
Message-ID: <4k4h7d$[e-mail]>
References: <[e-mail]> <4k0sbu$[e-mail]>

In article <4k0sbu$[e-mail]>,
   [e-mail] (Dale Chidester) wrote:
>In article [e-mail], Carl Estey
<[e-mail]> writes:
>....
> A penny was soldered on each end of the tubing to for the
>"plates" of a capacitor.
>
>....
>
>If you try to repeat this today, be sure to use "old" pennies.  Some time
in the
>70's they changed from all copper to copper plated zink!

There won't be any discernable difference between solid copper and
copper-plated zinc (or copper-plated anything) at radio frequencies,
provided that the plating is at least a few skin depths thick. And I'm sure
it's plenty thick enough on pennies.

Roy Lewallen, W7EL


From [e-mail] Tue Apr 09 16:59:40 1996
From: Will Flor <[e-mail]>
Newsgroups: rec.radio.amateur.antenna
Subject: Re: Antenna Farm
Date: 7 Apr 1996 03:56:23 GMT
Message-ID: <4k7ed7$[e-mail]>
References: <[e-mail]> <4k4lod$[e-mail]> <[e-mail]>

Ken Neal <[e-mail]> wrote:
>
>Can you tell me where to get the maps of ground conductivity.  I live just ou
tside of
>Washington, DC and have often gone to the Department of Commerce to buy maps
of various parts
>of the US, but don't remember the one you refer to.
>
>I don't want to spend money on a QTH, then more time and money on an antenna
system only to be
>defeated by the ground conditions.  Anyone who knows where I can get ground c
onductivity maps
>can reply to me here or by private email.
>

There's a conductivity map of the entire US in the ARRL Antenna
Handbook.  If you need a more detailed map, I don't know where
you'd look.  BTW, the soil conductivity at my QTH is relatively
low - just a few miles to the east, it's really high!  Unfortunately,
the high-conductivity ground is low (easily 200 feet below me) and
in the city (Milwaukee) so it's not for me; I'll just have to live
with my choice.

Hope this helped.

73 de Will KB9JTT




From [e-mail] Tue Apr 09 16:59:40 1996
From: Cecil Moore <[e-mail]>
Newsgroups: rec.radio.amateur.antenna
Subject: Re: Average Current on Ladder-Line
Date: Wed, 3 Apr 96 08:57:05 -0500
Message-ID: <[e-mail]>
References: <4jrmbe$[e-mail]> <4jtapl$[e-mail]>

WB3U <[e-mail]> writes:

>identical mirror images of each other.  Therefore, the current at
>Icenter will be equal to (Imax + Imin)/2 and it represents the
>average.

Hi Jack, I didn't realize it was a complicated question. I've
been asked whether I am talking about the mean, mode, or median
and have received as many answers as the number of emails.

Turns out the SWR current waveform is not a sine wave so it is
not (Imax-Imin)/2. The number I was looking for is SQRT(Imax*Imin).
I'm trying to calibrate my pickup loop using a 300 ohm dummy load.
With a calibrated pickup loop, I only need to know the pickup
loop current maximum reading to determine the SWR on the ladder-
line assuming I know the power in the line.

Thanks to everyone who responded here and through email.

73, Cecil, KG7BK, OOTC


From [e-mail] Tue Apr 09 16:59:41 1996
From: [e-mail] (W8JI  Tom)
Newsgroups: rec.radio.amateur.antenna
Subject: Re: Average Current on Ladder-Line
Date: 5 Apr 1996 08:29:05 -0500
Message-ID: <4k3771$[e-mail]>
References: <4k1ttd$[e-mail]>

In article <4k1ttd$[e-mail]>, Cecil Moore
<[e-mail]> writes:

>
>The basic purpose is to use the Ladder-Lizard to know everything about
>my antenna system, and I do mean *everything*. I don't need an antenna
>analyzer or network analyzer. The Ladder-Lizard tells me exactly the
>same thing as the expensive analyzers.
>
>73, Cecil, KG7BK, OOTC

That sounds great Cecil. You should write it up and send it to ARRL .
Maybe Bloom will put it in the Handbook so people can use it.

Ladder lizards sound much more useful than lot lizards.

73 Tom


From [e-mail] Tue Apr 09 16:59:42 1996
From: Cecil Moore <[e-mail]>
Newsgroups: rec.radio.amateur.antenna
Subject: Re: Average Current on Ladder-Line
Date: 3 Apr 1996 17:30:35 GMT
Message-ID: <4jucjr$[e-mail]>
References: <4jrmbe$[e-mail]> <4jtapl$[e-mail]> <[e-mail]> <4jucci$[e-mail]>

Cecil Moore <[e-mail]> wrote:
>Iavg=sqrt((Ifor^2)*(Irev^2))

Typo! Typo! should be Iavg=sqrt((Ifor^2)-(Irev^2))





From [e-mail] Tue Apr 09 16:59:43 1996
From: [e-mail] (WB3U)
Newsgroups: rec.radio.amateur.antenna
Subject: Re: Average Current on Ladder-Line
Date: Fri, 05 Apr 96 21:25:27 GMT
Message-ID: <4k43im$[e-mail]>
References: <4jrmbe$[e-mail]> <4k14n5$[e-mail]> <4k1ttd$[e-mail]>

Post / CC by Mail

   Cecil Moore <[e-mail]> wrote:
>[e-mail] (WB3U) wrote:

>There's no core. It's a Ladder-Lizard from TechnoLogic Concepts, a
>loop of wire driving a reversed biased diode.

I'm not familiar with this device so I'll assume for the sake of
argument that that it has no significant impact.

>On the other side of the reactances we know the voltage and current
are in phase at a current maximum and at a current minimum.

My mistake, sorry.  I had forgotten that the power is not reactive at
the nodes and loops.  Guess it's time for a Reflections refresher. :)

>With the inexpensive Ladder-Lizard, you can know *everything* about
>your transmission line including the transmitter feedpoint impedance,
>the antenna impedance, the impedance at *ANY* point whatsoever on the
>transmission line, the SWR, the forward and reflected power in the
>transmission line and the radiated power. You know *exactly* where to
>hang a single reactance to eliminate the reflections resulting in a
>perfect SWR=1:1.

OK, I'm sold.  Does it eat much?

>It's fairly safe to assume no common mode current with the 300 ohm
>dummy load fed by a current choke. So any common mode problems with
>the antenna system will appear as a reduction of power in the
>transmission line because common mode currents do not register on
>the Ladder-Lizard. (I think common mode currents could actually
>be measured with a figure-8 Ladder-Lizard.)

If the Lizard measures only one side of the line, the discrepancy
could also show up as an increase in current (power).  It will depend
on which side of the line is being measured.  In any event, in order
to compensate the power calculation, wouldn't it be necessary to know
all the same things about the system from a common mode viewpoint that
are known for differential power?  Common mode current, common mode
impedance (or voltage), common mode phase angle, common mode
reflections etc. would all combine in a way that's difficult to
quantify.  I'm open to ideas, but I'm not convinced that differential
measurements at nodes and loops will be valid if common mode operation
exists simultaneously.

>The basic purpose is to use the Ladder-Lizard to know everything
>about my antenna system, and I do mean *everything*. I don't need an
>antenna analyzer or network analyzer. The Ladder-Lizard tells me
>exactly the same thing as the expensive analyzers.

Tell me more about this device (what does it look like, where did you
buy it, how much does it cost, etc.).

Incidentally, this brings up another technique for simplifying the
overall antenna system that's somewhat related to yours.

In your system, you adjust the line for the correct resistive
component and then use a variable reactance to tune out the reactive
component.  However, if the line length was adjusted to eliminate
the reactive component first (by placing a current loop at the
transmitter), a tapped transformer could be used to achieve the match
to the transmitter.

This might exhibit slightly more loss than a single capacitor, but
not necessarily more than a parallel inductor (or two in series).  In
addition, it would be much less expensive than using L/C components
for the transformation, especially at higher power levels.

Of course, none of this deals with the common mode problem as far as
it relates to RF current flowing on the grounds in the shack.  That's
still my primary concern with a direct-coupled, non-resonant antenna.

73,
Jack  WB3U


From [e-mail] Tue Apr 09 16:59:45 1996
From: Cecil Moore <[e-mail]>
Newsgroups: rec.radio.amateur.antenna
Subject: Re: Average Current on Ladder-Line
Date: 4 Apr 1996 02:35:22 GMT
Message-ID: <4jvcha$[e-mail]>
References: <4jrmbe$[e-mail]> <4jtapl$[e-mail]>

[e-mail] (WB3U) wrote:
>
>Is this the concept of average current that you had in mind, or have I
>oversimplified?

Hi Jack, my fuzzy logic again. When I said "average current", I had in mind
the component of the forward current that gets radiated. That boiled down
to (Imax*Imin)*Z0 to get radiated power. I've never seen that written down
anywhere but of course, Ah'm blind in one eye and can't see outta tha' tother.

73, Cecil, KG7BK, OOTC  (not speaking for my employer)




From [e-mail] Tue Apr 09 16:59:46 1996
From: Cecil Moore <[e-mail]>
Newsgroups: rec.radio.amateur.antenna
Subject: Re: Average Current on Ladder-Line
Date: Sat, 6 Apr 96 14:09:13 -0500
Message-ID: <[e-mail]>
References: <4k1ttd$[e-mail]> <4k3771$[e-mail]>

W8JI  Tom <[e-mail]> writes:

>That sounds great Cecil. You should write it up and send it to ARRL .
>Maybe Bloom will put it in the Handbook so people can use it.

Hi Tom, All my ideas depend on conjugate matches and Z0-
matches to work. Since the ARRL is purging these concepts
from their writings, I don't think they would be interested.
After all, how could they print something that depends on
something in which they don't believe? If conjugate
matches don't exist then my methods won't work - but they
do work and are based on Walter Maxwell's "Reflections".
Thanks to W2DU, there are a handfull of hams who still
speak the truth.

73, Cecil, KG7BK, OOTC


From [e-mail] Tue Apr 09 16:59:46 1996
From: [e-mail] (W8JI  Tom)
Newsgroups: rec.radio.amateur.antenna
Subject: Re: Average Current on Ladder-Line
Date: 6 Apr 1996 00:02:16 -0500
Message-ID: <4k4tso$[e-mail]>
References: <4k43im$[e-mail]>

In article <4k43im$[e-mail]>,
[e-mail] (WB3U) writes:

>
>Of course, none of this deals with the common mode problem as far as
>it relates to RF current flowing on the grounds in the shack.  That's
>still my primary concern with a direct-coupled, non-resonant antenna.
>
>

It should be a concern with ANY antenna, resonant or not!

73 Tom


From [e-mail] Tue Apr 09 16:59:47 1996
From: [e-mail] (WB3U)
Newsgroups: rec.radio.amateur.antenna
Subject: Re: Average Current on Ladder-Line
Date: Sun, 07 Apr 96 00:49:17 GMT
Message-ID: <4k73t5$[e-mail]>
References: <4k1ttd$[e-mail]> <4k3771$[e-mail]> <[e-mail]>

   Cecil Moore <[e-mail]> wrote:

>If conjugate matches don't exist then my methods won't work - but
>they do work and are based on Walter Maxwell's "Reflections".
>Thanks to W2DU, there are a handfull of hams who still
>speak the truth.

Out of curiosity, what are they teaching EE's in college these days?
Do college texts agree with W2DU?

73,
Jack  WB3U


From [e-mail] Tue Apr 09 16:59:48 1996
From: Cecil Moore <[e-mail]>
Newsgroups: rec.radio.amateur.antenna
Subject: Re: Average Current on Ladder-Line
Date: Fri, 5 Apr 96 23:00:06 -0500
Message-ID: <[e-mail]>
References: <4jrmbe$[e-mail]> <4k14n5$[e-mail]> <4k1ttd$[e-mail]> <4k43im$[e-mail]>

WB3U <[e-mail]> writes:

>If the Lizard measures only one side of the line, the discrepancy
>could also show up as an increase in current (power).  It will depend

It's a loop that measures both sides of the line. Differential
currents add - common currents cancel.

>Tell me more about this device (what does it look like, where did you
>buy it, how much does it cost, etc.).

TechnoLogic Concepts ([e-mail]) sells the beast
along with an application note written by a ham outstanding
two acres in Queen Creek, AZ). :-)

>component.  However, if the line length was adjusted to eliminate
>the reactive component first (by placing a current loop at the
>transmitter), a tapped transformer could be used to achieve the match
>to the transmitter.

Funny you mention that. While I was out standing in my field,
I wrote an article for Radio Adventure suggesting the same thing.
I think the title wound up being, "Tune Any Antenna Tunerless".
BTW, I'm not asking or getting a penny out of this. It's just
time that everyone realized how easy it is to measure and tune
a ladder-line fed antenna.

>Of course, none of this deals with the common mode problem as far as
>it relates to RF current flowing on the grounds in the shack.  That's

It deals indirectly with the common mode problem. After calibrating
the Ladder-Lizard into a 300 ohm dummy load, We can measure how
g into the antenna. If it is not
close to what we are generating, then there is a problem to chase.
If it is close, then common mode stuff is not a problem.

73, Cecil, KG7BK, OOTC


From [e-mail] Tue Apr 09 16:59:50 1996
From: [e-mail] (WB3U)
Newsgroups: rec.radio.amateur.antenna
Subject: Re: Average Current on Ladder-Line
Date: Tue, 09 Apr 96 17:48:38 GMT
Message-ID: <4kefe7$[e-mail]>
References: <4k43im$[e-mail]> <4k4tso$[e-mail]>

Post / CC by Mail

   [e-mail] (W8JI  Tom) wrote:
>[e-mail] (WB3U) writes:

>>Of course, none of this deals with the common mode problem as far as
>>it relates to RF current flowing on the grounds in the shack. That's
>>still my primary concern with a direct-coupled, non-resonant
>>antenna.

>It should be a concern with ANY antenna, resonant or not!

Tom, this raises the issue that you brought up some time back.  How
does a balanced antenna driven from a balanced source create common
mode voltage on the line?  In discussing tuners and baluns on the air,
numerous people have asked me about this, particularly as it relates
to the "Measures" style tuner.

Could you post some info regarding this effect?

73,
Jack  WB3U


From [e-mail] Tue Apr 09 16:59:51 1996
From: Dave Perkins <[e-mail]>
Newsgroups: rec.radio.amateur.antenna
Subject: Beam Coordinate Headings for DX..
Date: 5 Apr 1996 07:10:01 GMT
Message-ID: <4k2h09$[e-mail]>

 I member seeing a chart that had beam headings for DX countries...For
example, if you wanted to put your beam to the Faukland Is. , then you
look at the chart and it tells you what heading to turn your rotator to
so your beam would be right on him...Im in San Diego, so does anyone know
where I could get one..??

 Thanx,
 Dave KC6ZBE



From [e-mail] Tue Apr 09 16:59:52 1996
From: [e-mail]
Newsgroups: rec.radio.amateur.antenna
Subject: Re: Beam Coordinate Headings for DX..
Date: Fri, 05 Apr 1996 23:45:10 GMT
Message-ID: <4k446u$[e-mail]>
References: <4k2h09$[e-mail]> <4k3l17$[e-mail]>

[e-mail] (Douglas Rhodes) wrote:

>AA7HL put together for me a neat spreadsheet using Excel (for Mac - he
>probably also made one up for Windows) which allows you to enter the
>latitude and longitude for your QTH and any other to which you wish to aim
>your antenna. It will give bearing coordinates, great circle distance in
>statute or nautical miles, plus some other stuff. Give me a shout if this
>is of interest to you and I'll put a copy on a disc and ship it .

>73

>Doug Rhodes - VE7DFZ

Hi Doug,

I have a similar program that I did in Excel for win 95 and also 123
that has all current countries and when u enter ur coords, provides
beam headings for each one.  I will send it to anyone wanting it on
request as encoded e-mail (Eudora 1.something)

Let me know

Dean


           C. Dean Norris
      Amateur Radio Station K7NO
      e-mail to [e-mail]



From [e-mail] Tue Apr 09 16:59:52 1996
From: [e-mail] (Cedric Baechler HB9HFN)
Newsgroups: rec.radio.amateur.antenna
Subject: Beam TH3JR
Date: Fri, 05 Apr 1996 16:47:00 GMT
Distribution: world
Message-ID: <29KrKJ$00Z@hb9hfn>
Reply-To: [e-mail]

Hi,

I've got a 3 elements beam from a friend. It's a Hy-Gain but he had no
manual anymore. I think it should be a TH3JR.

Could someone give me the dimensions, measurements of the boom and its
elements of this antenna so that I can be sure I've mounted the elements in
the right order. What element is the closest to the radiator?

Tnx for any info, 73, Cedric HB9HFN


From [e-mail] Tue Apr 09 16:59:54 1996
From: [e-mail] (Gary Mager)
Newsgroups: rec.radio.shortwave,rec.radio.amateur.antenna
Subject: Best antenna : RVer / MW DX / GE SRIII?
Date: Fri, 05 Apr 1996 16:06:47 GMT
Message-ID: <[e-mail]>
Reply-To: [e-mail]

Hi all :

        We're full-time RV'ers and I like to listen to AM DX as we
travel.  We're currently in the Tucson area, and I'd really like to
try a better antenna. I'm currently using the internal antenna on my
GE SuperRadio III, and the radio essentially has zero ability to
receive AM inside our Airstream trailer.  I've tried a long-wire
antenna hung outside the window, and that works a little better, but
still not great.  Lots of noise and whistles from interference
generated inside the trailer.  I normally listen outside, again using
the internal antenna.  Does anyone have recomendations for antennas
that may be suitable for my situation?  I've considered the active
antennas like the AN-1, but suspect that it may end up not being much
better than my longwire (20').  I think that I might get the best
"bang for the buck" from a modified Select-a-tenna, continuing to
listen outside the RV.


Thoughts and recommendations?


Gary




From [e-mail] Tue Apr 09 16:59:55 1996
From: [e-mail] (WB3U)
Newsgroups: rec.radio.amateur.equipment,rec.radio.amateur.antenna
Subject: Coax Shield Current (Was Re: MFJ Artificial Ground)
Date: Sun, 07 Apr 96 06:36:34 GMT
Message-ID: <4k7v9d$[e-mail]>
References: <4jtsrr$[e-mail]> <4jue3f$[e-mail]> <[e-mail]> <4k1h27$[e-mail]> <[e-mail]>

   [e-mail] (Gary Coffman) wrote:

>That's assuming the currents are flowing to "ground", Jack. But
>that's not what they do.  The current is trying to "close the
>loop" back to the source, Kirchhoff's law, and the source is
>inside a Faraday box called a transmitter.

Gary, this has nothing to do with Kirchoff's law.  Once the RF exits
the coax at the antenna, it will be attracted to *any* conductor that
has a lower EMF than itself.  It doesn't matter whether that conductor
is the antenna, the shield, the B- of the transmitter, or twelve
bronzed monkeys holding hands and singing Nowhere Man.  Anything the
RF can reach that will conduct, dissipate or radiate is fair game.

>The RF currents on the outside of that box can't get in, can't close
>the loop, and therefore that model fails.

The only model that fails is the one you've described, because it
doesn't exist.  Not only is the inner chassis of the transmitter not
the primary target of the current, it isn't even sealed. Take the key
jack for example.  One conductor is usually connected to the external
chassis by the frame of the jack.  The other conductor typically has a
bypass capacitor from the tip of the jack to the inner chassis.  So
what happens when you close the key?  Zappo!  The outer chassis is
connected to the inner chassis through the key and the bypass
capacitor.  This is also why the key contacts often spark when there's
RF on the chassis of the transmitter.

The point is Gary, the concentrically-shielded RF source you're
envisioning doesn't exist relative to currents flowing on the outer
cabinet.  Even if you don't agree with anything else, you should at
least abandon this concept.

73,
Jack  WB3U


From [e-mail] Tue Apr 09 16:59:57 1996
From: [e-mail] (WB3U)
Newsgroups: rec.radio.amateur.equipment,rec.radio.amateur.antenna
Subject: Coax Shield Current (Was Re: MFJ Artificial Ground)
Date: Sun, 07 Apr 96 04:07:40 GMT
Message-ID: <4k7fh8$[e-mail]>
References: <4k43ol$[e-mail]> <4k4tth$[e-mail]>

Our news server crashed today so I'm not sure my first copy of this
went out.  Likewise, Gary's article still hasn't appeared here, so I'm
commenting on the basis of the text Tom quoted.

   [e-mail] (W8JI  Tom) wrote:
>(Gary Coffman) writes:

>>Tom's mistake is trying to use transmission line theory on what is
>>*not* at this point functioning as a transmission line.

The concept of 1/4 and 1/2 wave lines applies equally well to single
conductors.  This is evidenced by the use of 1/4 wave single-conductor
decoupling stubs in microwave circuitry.

>>It is, instead, an unintended end fed 1/2-wave antenna. Now while it
>>is true that the ends of such an antenna are voltage maxima, that's
>>because the ends are very high impedances, and thus not much current
>>will "turn the corner" to excite this "antenna", so there won't be
>>much high voltage down at the shack end.

This paragraph entirely contradicts itself in trying to prove that a
1/2 wave conductor will isolate antenna currents from the transmitter.
First it states that because the 1/2 wave shield simulates a 1/2 wave
end-fed antenna, the voltage and impedance on both ends will be high.
Then it says that because little current will flow, one end will
actually be low.

>>OTOH, a 1/4-wave will be a low feed impedance at the antenna, thus
>>lots of current will divert down toward the shack, and will express
>>itself as a high voltage at the high impedance of the other end.

Another contradiction; this paragraph says the same thing about the
1/4 wave shield that the previous paragraph said about the 1/2 wave -
that one end will have a higher impedance than the other.  This time
it's true, but the rest of the explanation is incorrect.

Yes, there is a low feedpoint impedance at the antenna, but it's
created by the 1/2 wave dipole, not the shield.  The 1/4 wave shield
looks like a high impedance due to reflections from the other end,
therefore current does not flow toward the shack as claimed.

>>(And the other end *will* be a high impedance because the current
>>can't penetrate the coax shield or the transmitter case to "close
>>the loop" with the driving source.

This is also incorrect.  The RF voltage at the antenna is a free agent
that is attracted to *all* conductive objects with a lower potential.
That includes any object connected to earth or to the B- of the
transmitter, as well as any object large enough to convert the current
into radiated energy.  The latter is the "electrical mass" that Tom
often refers to.

Let's analyze the transmitter in this regard.  If it was totally
isolated from earth, the outer chassis would "float" at some RF
potential due to the connection between the chassis and the outer
shield of the coax.  This would be true regardless of shield length,
because in practice even the input impedance of a 1/4 wave shield
(at the antenna) won't be infinitely high and some current will flow.

However, the trasnmitter is not isolated from earth.  It is coupled to
earth by means of AC lines and other equipment.  Even if this coupling
is very loose, it is sufficient to pull the chassis to near-ground
potential due to the isolation provided by the 1/4 wave shield.

As a side note, earth is likely to be more effective at this than even
a direct connection to the inside of the transmitter.  Unlike earth,
the effectiveness of B- as a return path for common-mode current is
determined in part by the relative phase between current leaving the
transmitter and current arriving at B- by way of the shield.

It's also my belief that the outer chassis of a transmitter is not
well-isolated from internal grounds as previously claimed, and that
phase and amplitude differences are the real reason the shield current
cannot be cancelled by merely returning to B-.  At the very least,
this lack of isolation appears to be confirmed by the fact that RF on
the outer chassis will often create internal equipment malfunctions.

>>Whether the transmitter case is connected to Earth or not is largely
>>irrelevant as well.)

This statement can only be accepted if one believes that RF voltage
is not attracted to earth.

73,
Jack  WB3U


From [e-mail] Tue Apr 09 16:59:59 1996
From: [e-mail] (WB3U)
Newsgroups: rec.radio.amateur.equipment,rec.radio.amateur.antenna
Subject: Coax Shield Current (Was Re: MFJ Artificial Ground)
Date: Mon, 08 Apr 96 11:21:54 GMT
Message-ID: <4kb4cq$[e-mail]>
References: <4k43ol$[e-mail]> <4k4tth$[e-mail]> <[e-mail]>

   [e-mail] (Gary Coffman) wrote:

>I'm also fascinated with your fondness for the peculiar properties
>you assign to "ground" and "electrical mass".

I've been thinking that the crux of this argument might be the
perceived impedance of the transmitter chassis.  I finally decided to
look up the subject of antenna current in the ARRL Antenna Handbook.

The discussion in the Handbook is centered on the use of balanced
feeders, but a subsequent paragraph states that the discussion applies
equally well to coax.  I think the text is sufficient to resolve much
of our disagreement (unless we choose not to believe it).  ;)

Here's what I found:

1.  The first scenario presented in the discussion tends to agree with
Gary's claim regarding use of a 1/2 wave long shield.  It states that
the total length of the line plus one side of the 1/2 wave antenna
should *not* be an integral multiple of 1/2 wave.  In other words, the
feedline should *not* be an odd multiple of 1/4 wave.

However, the condition to which this is applied is when the line is
connected to a coupling circuit that is not grounded, either directly
or through a capacitance of more than a few picofarads.

2.  The second scenario agrees with the claim by Tom and myself that
a 1/4 wave shield should be used.  It states that the feedline plus
one side of the antenna should be equal to multiples of 1/2 wave.  In
other words, the feedline should be an odd multiple of 1/4 wave.

The condition this applies to is when "the coupling apparatus is
grounded at the transmitter."  The text goes on to say that "in the
average station, it is not possible to get a connection to real ground
without having a lead that is an appreciable fraction of a wavelength
long" but "if the trasnmitter has fairly large capacitance to
ground, a system of this length will be effectively detuned for the
fundamental and all even harmonics when grounded to the transmitter at
the coupling apparatus."

The latter agrees closely with what I've been saying about the ability
of the loose coupling to ground being able to pull the "residual"
voltage to near-ground potential, so long as a 1/4 wave line is used.

To sum this up, when coax is used, the system does *not* present the
extremely high impedance to ground that might otherwise require
the use of a 1/2 wave line.  If coax is in use and the station is
operated in the usual manner, a 1/4 wave line will detune the system
for antenna currents.

73,
Jack  WB3U


From [e-mail] Tue Apr 09 17:00:00 1996
From: [e-mail] (WB3U)
Newsgroups: rec.radio.amateur.equipment,rec.radio.amateur.antenna
Subject: Coax Shield Current (Was Re: MFJ Artificial Ground)
Date: Mon, 08 Apr 96 14:20:09 GMT
Message-ID: <4kbeqv$[e-mail]>
References: <4k43ol$[e-mail]> <4k4tth$[e-mail]> <[e-mail]>

   [e-mail] (Gary Coffman) wrote:

>Let me try to summarize my case so that we can focus on the exact
>point of disagreement.

>1) The outside of the coax is not acting as a transmission line,
>   and thus transmission line theory does not apply.

Wave reflection theory will apply.

>2) The outside of the coax is acting as a halfwave resonant
structure, IE antenna, and antenna theory must apply.

Antenna theory based on unterminated lines will not apply.  The 1/2
wave shield is not unterminated.

>3) The standing wave on a halfwave antenna forces the ends to be
>   voltage maxima.

This is true of both the antenna and the 1/2 wave shield.

>4) Ergo, the ends of a halfwave antenna are high impedance points.

This statement is true, but because of the error in (2), it does not
apply to the 1/2 wave shield.

>5) And finally, a high impedance load driven by a low impedance
>   source won't accept much current.  Therefore use of a halfwave
>   coax feeder will limit the amount of RF current conducted down
>   to the shack end of the coax along the coax's outer surface.

The first sentence is true, but no valid basis for the conclusion has
been presented.

>Now tell me where any of that is wrong, and we can proceed from
>there.

In a nutshell, you're mixing absolute and relative terms.  You've used
"low" when the correct term is "less", and "high" when the correct
term is "greater".  This has led to incorrect conclusions regarding
both the 1/2 wave and 1/4 wave shield lengths.

You're also applying theory based on unterminated conductors to a
shield that is terminated by a finite degree of coupling to earth at
the transmitter.

73,
Jack  WB3U


From [e-mail] Tue Apr 09 17:00:01 1996
From: [e-mail] (WB3U)
Newsgroups: rec.radio.amateur.equipment,rec.radio.amateur.antenna
Subject: Coax Shield Current (Was Re: MFJ Artificial Ground)
Date: Mon, 08 Apr 96 09:38:25 GMT
Message-ID: <4kaual$[e-mail]>
References: <4jtsrr$[e-mail]> <4jue3f$[e-mail]> <[e-mail]> <4k1h27$[e-mail]> <[e-mail]>

My apologies if this is posted twice.  Our news server crashed
recently and is still unstable.  I am having considerable difficulty
reading and posting news.  :(

   [e-mail] (Gary Coffman) wrote:

>That's assuming the currents are flowing to "ground", Jack. But
>that's not what they do.  The current is trying to "close the
>loop" back to the source, Kirchhoff's law, and the source is
>inside a Faraday box called a transmitter.

Gary, this has nothing to do with Kirchoff's law.  Once the RF exits
the coax at the antenna, it will be attracted to *any* conductor that
has a lower EMF than itself.  It doesn't matter whether that conductor
is the antenna, the shield, the B- of the transmitter, or twelve
bronzed monkeys holding hands and singing Nowhere Man.  Anything the
RF can reach that will conduct, dissipate or radiate is fair game.

>The RF currents on the outside of that box can't get in, can't close
>the loop, and therefore that model fails.

The only model that fails is the one you've described, because it
doesn't exist.  Not only is the inner chassis of the transmitter not
the primary target of the current, it isn't even sealed. Take the key
jack for example.  One conductor is usually connected to the external
chassis by the frame of the jack.  The other conductor typically has a
bypass capacitor from the tip of the jack to the inner chassis.  So
what happens when you close the key?  Zappo!  The outer chassis is
connected to the inner chassis through the key and the bypass
capacitor.  This is also why the key contacts often spark when there's
RF on the chassis of the transmitter.

The point is Gary, the concentrically-shielded RF source you're
envisioning doesn't exist relative to currents flowing on the outer
cabinet.  Even if you don't agree with anything else, you should at
least abandon this concept.

73,
Jack  WB3U


From [e-mail] Tue Apr 09 17:00:02 1996
From: [e-mail] (Terry Dunlap, AC6EF)
Newsgroups: rec.radio.amateur.equipment,rec.radio.amateur.antenna
Subject: CQ 80m CQ Maine
Date: 2 Apr 96 15:17:19 PST
Message-ID: <[e-mail]>

I'm trying to finish up the 80m portion of 5BWAS and I'm down to one
state......Maine.  Are there any Maine hams out there who would be
interested in setting up a sked??  It can be either CW or SSB.

Please don't suggest I try a net.....I'd prefer to do it on my own.

Reply via email...

73 de Terry AC6EF
[e-mail]



From [e-mail] Tue Apr 09 17:00:03 1996
From: [e-mail] (Douglas Rhodes)
Newsgroups: rec.radio.amateur.antenna
Subject: Field Day Special
Date: 4 Apr 1996 17:23:40 GMT
Message-ID: <4k10is$[e-mail]>

Many thanks, Roy, for the 15 meter Field Day Special dimensions.
I neglected to mention that the primary provocation for
re-cutting the 20 meter FD-special was that my *strain relief*
fittings provided more strain than relief and the twinlead
finally parted. The feed point fitting involved snaking the
twinlead through a slotted strip of PVC, which is where it broke.
If I can work out a better way to secure the twinlead, I'll post
my findings.

I was also pleased to see that you re-designed the phasing line
to be slightly greater in length than the element spacing. In the
original design, the spreaders maintained the element spacing at
the ends, but the center always seemed pulled together somewhat
by the droop of the phasing line. I had considered adding a
mid-point spreader, but didn't want the extra weight. Your new
design appears to include the remedy while retaining performance
objectives.

Sorry about the way I spelled your name in my original posting. I
must have wanted to turn you into a Welshman...

73

Doug Rhodes - VE7DFZ
Victoria, British Columbia



From [e-mail] Tue Apr 09 17:00:05 1996
From: [e-mail] (Scott Rosenfeld NF3I)
Newsgroups: rec.radio.swap,rec.radio.amateur.antenna,dc.forsale.misc,um.forsale
Subject: FS: Cushcraft A3S tribander, new
Date: 6 Apr 1996 05:10:27 GMT
Message-ID: <4k4uc3$[e-mail]>

I have for sale a Cushcraft A3S 3 element triband Yagi.  It is new
and has never been assembled, although it has been removed from the
box to verify that all parts were present.  Two of the larger pipes
have some scratches at one end, but they're going to get there
anyway when you assemble it.

Never fully assembled, and never exposed to the weather.

They sell new for $329 at AES and elsewhere.  14' boom, 8 db gain.
Turning radius of 15.5 feet, 4.36 sq. ft. wind load, total wgt 27 lbs.
All stainless steel hardware!

Asking $260 ($70 under current price) and you ship.  E-mail or call!
--
* Scott Rosenfeld NF3I Burtonsville, MD FM19  QRV 80-10/6/2/440 *
*** VHF @ <25w, HF @ <5w *** Save a cake, pound BRASS instead ***
* 138 cfd with dipoles * QRP-L #147 QRP ARCI #9054 DXCC/WAS/WAC *
* 301-549-1022 h / 301-982-1015 w * 145.490-  147.225+ PL 156.7 *


From [e-mail] Tue Apr 09 17:00:05 1996
From: [e-mail] (beard)
Newsgroups: rec.radio.amateur.antenna
Subject: FS: HP 608D Signal Generator
Date: 3 Apr 1996 21:04:44 GMT
Message-ID: <4jup5c$[e-mail]>

I have a very good HP 608D signal generator for sale.  It is in good
physical and functional condition and has a good copy of the maintenance
manual.  10 - 420 Mhz.

$150.00 and I will pay shipping in continental USA

David Beard
WA4QGA



From [e-mail] Tue Apr 09 17:00:06 1996
From: John Fleming <[e-mail]>
Newsgroups: rec.radio.amateur.antenna
Subject: Half-Square DX Machine
Date: Mon, 08 Apr 1996 08:24:40 +0500
Message-ID: <[e-mail]>

Do you want to turn your ordinary 40-meter dipole into a DX monster?
Read the weekly RadioAdventure article

http://www.far.net/radioadventure/weekly.htm

John N9NDH


From [e-mail] Tue Apr 09 17:00:07 1996
From: [e-mail] (Pablo Lewin)
Newsgroups: rec.radio.amateur.antenna
Subject: HAM III/CD44 Rotor problems, pelase help! :-(
Date: Mon, 08 Apr 1996 19:35:38 GMT
Message-ID: <4kbpoc$[e-mail]>
Reply-To: [e-mail]

Hi, and thank you for reading this

I have a HAM III/CD44  (CDE) rotor and controller, the rotor works
really well, however the heading indicator stopped working yesterday,
it just won't "track" anymore and the needle is not physically stuck,
I fear that I may have misplaced a wire and I don't have the
schematic/owners manual.        Does anybody out there know how to find out
how the wires are connected ?, any troubleshooting techniques for the
meter?, could anybody send me the text or the GIF of the Schematic (or
both)?, where can I get an old owner's manual?/ book?

Any help appreciated, thanks in advanced

Pablo Lewin
WA6RSV
please reply through e-mail to  [e-mail]



From [e-mail] Tue Apr 09 17:00:08 1996
From: [e-mail] (Jim Keesler)
Newsgroups: rec.radio.amateur.antenna
Subject: INFO WANTED ON ISOTRON ANTENNAS
Date: 6 Apr 96 00:07:25 GMT
Message-ID: <[e-mail]>

After reading the glowing report in the new "73 MAGAZINE" about the ISOTRON
antenna (75 meters),  I'd like to hear some other reports.  Am considering
it for our Red Cross ham station that is in a downtown historic area without
much room for conventional wire antennas.

My instincts say if it's compact, you're giving up efficiency or bandwidth
or both!

73,
Jim, K8EXF



From [e-mail] Tue Apr 09 17:00:09 1996
From: Jim <[e-mail]>
Newsgroups: rec.radio.amateur.antenna
Subject: Re: Isotron Antennas
Date: 5 Apr 1996 18:19:13 GMT
Message-ID: <4k3o71$[e-mail]>
References: <[e-mail]>

Isotrons work, but they're fussy on tuning and have a narrow bandwidth.

Given a choice of an Isotron or NOTHING, I'd choose the Isotron.  I used
a 40/80 Isotron one Field Day, and saw a 3 - 5 db signal loss compared
to low-elevation dipoles.  But they do work...gotta be patient to
get them resonant, though, and QSY is pretty much out of the question.

For freqs. above 30 meters, I'd strongly recommend a tunable loop
antenna if you're seriously challenged for space or if you have
to have an invisible antenna.  You might also consider a pair of
screwdriver antennas (DK3 mobile antenna) mounted end to end and
set up as a rotable horizontal dipole.

Since I had such good results with a Butternut multi-band vertical and
with plain ol' dipoles, I woudn't go back to an Isotron now.

73    Jim N6OTQ




From [e-mail] Tue Apr 09 17:00:11 1996
From: [e-mail] (WB3U)
Newsgroups: rec.radio.amateur.antenna
Subject: Re: Johnson Matchbox tuners
Date: Fri, 05 Apr 96 21:27:57 GMT
Message-ID: <4k43nb$[e-mail]>
References: <4k2bi6$[e-mail]>

   [e-mail] (Douglas Rhodes) wrote:

>With only an SWR meter and a Johnson Matchbox, what assumptions could
>one make about the antenna characteristics based on the positions of
>the *tuning* and *matching* controls? e.g., if either *tuning* or
>*matching* need to be zero in order to yield the lowest indicated SWR
>(not necessarily a unity, BTW), can one deduce whether the antenna is
>too short or too long, or is the picture too complex?

The output circuit of the Match Box consists of a 2-section
differential capacitor.  In the schematic, this appears as a pair
of capacitors in series with the line, followed by two capacitors
across the line.  The relationship between the adjustment of this
capacitor, resonance of the coil and the resistive/reactive components
present on the line is complex.  In addition, it is somewhat difficult
to define the impedance transformation through the link because it
varies as a function of the L/C ratio.  I suspect the controls could
indeed be calibrated to provide useful information, but it would
probably require more test equipment than the analyzer that would
measure feedpoint characteristics directly.

>Would feedline (52 ohm coax) length as a function of wavelength
>affect those settings?

Unless the feedline is an exact multiple of an electrical half
wavelength, you can't meaure the characteristics of the antenna
itself at the feedpoint to the line.

73,
Jack  WB3U


From [e-mail] Tue Apr 09 17:00:12 1996
From: [e-mail] (Tom Bruhns)
Newsgroups: rec.radio.amateur.antenna
Subject: Re: Johnson Matchbox tuners
Date: 9 Apr 1996 15:18:37 GMT
Message-ID: <4kdv4d$[e-mail]>
References: <4kbnsg$[e-mail]>

Jim Garver ([e-mail]) wrote:

: The Matchbox(tm) will not match impedences much higher than 1500-2000 ohms.
: Its easy to get yourself into a feedpoint impedance exceeding 10,000 ohms.
: Try matching a 40 meter dipole on 20 meters for instance.

..

: The easiest thing to do is change the length of the antenna or feedline unti
l
: you get the feed impedance down low enough to match.  If you are using
: ladder line, as you always should with a Matchbox, then changing the antenna
: length will be the most effective.

Another way that's quite effective, though admittedly not quite so easy, is
to make the antenna effective diameter large.  If you make a "cage" dipole,
or even just two or three wires on each side spread apart by a few inches,
the maximum feedpoint impedance for a center-fed dipole will drop to under
1000 ohms, for HF antennas.  Of course, if the antenna is way too short, it
can be too low an impedance and reflect back a very high impedance through
ladder line.  This could be a danger of using 450 ohm line!  If the antenna
feedpoint is 75 ohms and the line is lossless, a quarter wave down 450 ohm
line would look like 2700 ohms; if the antenna is short and looks more like
10 ohms with a bunch of capacitive reactance, you could get some rather
high impedances reflected back to the line input.  But a 300 ohm line
feeding a cage doublet which is at least 1/2 wavelength long should work
out to a reasonable impedance for your Matchbox to tune.


--
Cheers,
Tom
[e-mail]


From [e-mail] Tue Apr 09 17:00:13 1996
From: [e-mail] (CHARLES J. MICHAELS)
Newsgroups: rec.radio.amateur.antenna
Subject: Re: Ladder Line for VHF/UHF
Date: 6 Apr 1996 20:16:54 GMT
Message-ID: <4k6jfm$[e-mail]>


Ian White wrote -

Quoting a different analysis from Terman, G6XN gives the power radiated
from a balanced line carrying I amps as:

  P_r = 160 * (pi * D)^2 * I^2

where D is the spacing as a fraction of a wavelength.

[ BTW, this equation has the strange property that P_r is independent of
the total length of line. I don't have the 1943 edition of Terman's
'Radio Engineer's Handbook' (not the more common 'Radio Engineering')
which G6XN references - can anybody comment, please? ]


Ian,
        I have seen this explained as the radiation from the length of
the connections from the line wires at the feedpoint and at the termination
point to a presumably negligible small dimensioned source and load
respectively (or the lenght of the source and load in the same place of
course) and NOT from the line length itself.


Charlie,  W7XC
--


From [e-mail] Tue Apr 09 17:00:14 1996
From: [e-mail] (WB3U)
Newsgroups: rec.radio.amateur.antenna
Subject: Re: Ladder line length
Date: Fri, 05 Apr 96 06:58:08 GMT
Message-ID: <4k2gob$[e-mail]>
References: <[e-mail]> <4k0vjm$[e-mail]> <4k1pi0$[e-mail]>

Post / CC by Mail

   Cecil Moore <[e-mail]> wrote:

>Hi Tom, KE7QJ tried his 65 ft. dipole on 75m. His 1:1 choke
>balun cores got hot to the touch. He's obviously losing some
>power even with the 1:1 choke balun. Could you describe the
>mechanism causing the heating? I think his cores are #77
>material.

Cecil,

75 and 77 mixes are highly resistive at HF.  Amidon recommends the
latter for noise attenuation to 50 MHz, but also states that both
types offer low core loss in the range from 1 KHz to only 1 MHz. This
means that the material is fine for reducing unwanted HF noise, but
the resistive nature of the mix causes significant absorption in the
core at those frequencies.

If your friend is using large toroids such as the FT-240 size, he
should switch to 43 or even 61 material for use from 160 - 10M.  If
he's using beads over coaxial shield, a mixture of 73 and 43 types
will help control heating (see below).

It's my opinion that a choke balun bifilar wound on a toroid will
produce a much lower loss device than beads.   The increased AL that
results from the larger core of a toroid, in addition to the
additional inductance created by multiple turns, allows using a lower
permeability and lower loss material.  Core flux created by the
bifilar windings also tends to cancel in the core, further reducing
loss.

Back to the beads, another phenomenon of these chokes is that the
beads closest to the feedpoint generate the most heat. It isn't clear
to me why the beads don't act as a single ferrite sleeve, but those
near the feedline obviously experience a greater voltage drop than
those further out.

The heating is most prevalent with 75 and 77 materials, and to a
lesser extent in 73.  43 is the best in this regard, but it takes
quite a few beads of this mix to achieve an effective choke on 160M.
In the choke I built recently, I used 43 mix near the output of the
balun to control heating, and 73 mix further back to achieve
sufficient total impedance.

This will be the last choke balun I build with beads, however.  The
toroidal design is less costly and I'm convinced that it offers
significant advantages.

73 (and also 61, 75, 77, 43),
Jack  WB3U


From [e-mail] Tue Apr 09 17:00:16 1996
From: jsutton@pop,erols.com
Newsgroups: rec.radio.amateur.antenna
Subject: Re: Ladder line length
Date: 7 Apr 1996 15:09:34 GMT
Message-ID: <4k8lre$[e-mail]>
References: <[e-mail]>

>   [e-mail] writes:
>
>  In Article<[e-mail]>, <[e-mail]> write:
>  > Path:
interramp.com!interramp.com!psinntp!psinntp!gatech!newsfeed.internetmci.com!ns
2.borg.c
om!usenet
>  > From: [e-mail] (Scott D. Souva)
>  > Newsgroups: rec.radio.amateur.antenna
>  > Subject: Ladder line length
>  > Date: Thu, 28 Mar 1996 13:54:33 GMT
>  > Organization: Borg
>  > Lines: 13
>  > Message-ID: <[e-mail]>
>  > NNTP-Posting-Host: l8.borg.com
>  > X-Newsreader: Forte Agent .99d/32.182
>  >
>  > I'm about to hang a 160 meter dipole and will use 450 ohm ladder line
>  > into an antenna tuner.  My question is-- how long should the feedline
>  > be?  I've got 100 feet of the stuff and would like to cut it to an
>  > optimal length.
>  >
>  > If I end up cutting the feedline to a specific length, how should the
>  > excess feedline be handled (coiled up...)?
>  >
>  > Any ideas would be welcome.
>  >
>  >
>  > Scott Souva
>  > [e-mail]
>  Scott:  I have just read your post and all the replies.
>  Put up your wire, either 135 feet or 270 feet as high as you can get it.
>  Make the feed line as long as you can, keep the 100 feet if possible.
>  Keep it a foot or so away from metal such as gutter and your tower.
>  My 450 ohm ladder line lies on the roof, then it is suspended on a piece of

>  pressure treated lumber to keep it away from the gutter, then it comes thro
ugh
>  a hole I drilled inthe concrete block wall of my basement.
>  I feed it through a big old MFJ tuner.  With my 3 watt       qrp RIGS ON 80 AND
40,
>  I reliably work Europe and S America on CW.
>
>
>>>>Scott -- the optimum length for your ladder line to your tuner is the dist
ance from your
antennat to your tuner.  Don't worry about trying to get an optimum length.  I
 have a run from
my rig in the basement - into the garage - outhrough a hole in the side - over
 the garage
roof - over the house roof to a 90 foot non resonant sloping v dipole.  Works
fine.  Keep the
line away from metal as much as possible -

Good Luck - Jim/AC4CZ



From [e-mail] Tue Apr 09 17:00:17 1996
From: [e-mail] (WB3U)
Newsgroups: rec.radio.amateur.antenna
Subject: Re: Ladder line length
Date: Fri, 05 Apr 96 07:04:00 GMT
Message-ID: <4k2h3a$[e-mail]>
References: <[e-mail]> <[e-mail]> <[e-mail]>

   Cecil Moore <[e-mail]> wrote:
><[e-mail]> writes:

>>I feed it through a big old MFJ tuner.  With my 3 watt        qrp
>>RIGS ON 80 AND 40, I reliably work Europe and S America on CW.

>If you are using the balun in the MFJ for all-band operation,
>you are most likely losing a lot of power on some bands.
>Seems the conclusions reached here is not to use baluns
>unless they see a near resistive relatively low impedance.

The same conclusion can be found in ARRL literature; it's just not as
obvious as in this newsgroup.  ;)

73,
Jack  WB3U



From [e-mail] Tue Apr 09 17:00:18 1996
From: [e-mail] (Roy Lewallen)
Newsgroups: rec.radio.amateur.antenna
Subject: Re: Ladder line length
Date: Sun, 07 Apr 96 23:05:02 GMT
Message-ID: <4k9hl2$[e-mail]>
References: <[e-mail]> <4k0vjm$[e-mail]> <4k1pi0$[e-mail]> <4k2gob$[e-mail]>

In article <4k2gob$[e-mail]>,
   [e-mail] (WB3U) wrote:

>Back to the beads, another phenomenon of these chokes is that the
>beads closest to the feedpoint generate the most heat. It isn't clear
>to me why the beads don't act as a single ferrite sleeve, but those
>near the feedline obviously experience a greater voltage drop than
>those further out.

I've heard reports of this from several good sources, and have attempted to
duplicate it, because I'd like to understand what the mechanism is. Try as
I might, though, I have never been able to produce obviously uneven
heating, or appreciable current differences, between beads in any
experiment I've been able to set up. If you or anyone else has a test setup
which will reliably demonstrate uneven bead heating, I'd appreciate a
detailed description so I can duplicate and study it.

Thanks!

Roy Lewallen, W7EL


From [e-mail] Tue Apr 09 17:00:19 1996
From: [e-mail] (WB3U)
Newsgroups: rec.radio.amateur.antenna
Subject: Re: Ladder line length
Date: Tue, 09 Apr 96 17:08:35 GMT
Message-ID: <4ked35$[e-mail]>
References: <[e-mail]> <4k0vjm$[e-mail]> <4k1pi0$[e-mail]> <4k2gob$[e-mail]> <4k9hl2$[e-mail]>

Post / CC by Mail

   [e-mail] (Roy Lewallen) wrote:
>   [e-mail] (WB3U) wrote:

>>Back to the beads, another phenomenon of these chokes is that the
>>beads closest to the feedpoint generate the most heat. It isn't
>>clear to me why the beads don't act as a single ferrite sleeve, but
>>those near the feedline obviously experience a greater voltage drop
>>than those further out.

>I've heard reports of this from several good sources, and have
>attempted to duplicate it, because I'd like to understand what the
>mechanism is. Try as I might, though, I have never been able to
>produce obviously uneven heating, or appreciable current differences,
>between beads in any experiment I've been able to set up. If you or
>anyone else has a test setup which will reliably demonstrate uneven
>bead heating, I'd appreciate a detailed description so I can
>duplicate and study it.

Hi Roy,

I was quoting the bead suppliers.  I've only built one of these baluns
and it consists of approximately 150 beads on teflon coax, with the 43
mix at the output (in anticipation of the problem).  I mounted the
balun on large homebrew teflon standoffs inside my floating single-
ended tuner.

Unfortunately, I didnt't use this combination for long due to
continuing problems with shack RF, and I don't remember if I drove it
with my amplifier.  Also, because the balun was inside the tuner, I
didn't bother to check it for heating.

If you'd like a balun like this for a test, I'd be glad to send it to
you.  This one uses small beads over teflon coax about the size of
RG-58 (I don't remember the number offhand). If you've been using
larger beads, maybe this one would show the problem more readily.  You
could easily remove the (50) 43's and use only the (100) 73's for a
test.  I color coded the beads so they can't be mixed up accidentally.

BTW, would it be possible for you to e-mail a copy of your recent air
core balun article to me?  Our news server has been on the fritz and
it never appeared in the newsgroup here.

73,
Jack  WB3U
[e-mail]


From [e-mail] Tue Apr 09 17:00:21 1996
From: [e-mail] (WB3U)
Newsgroups: rec.radio.amateur.antenna
Subject: Re: Ladder line length
Date: Tue, 09 Apr 96 17:09:19 GMT
Message-ID: <4ked4h$[e-mail]>
References: <4k0vjm$[e-mail]> <4k1pi0$[e-mail]> <4k2gob$[e-mail]> <4k9hl2$[e-mail]> <[e-mail]> <4ke4rv$[e-mail]>

   [e-mail] (Roy Lewallen) wrote:
>   [e-mail] (Graham Seale) wrote:

>>As for the beads heating unevenly when spread out along a feedline
>>carrying a large common mode component. Well.... maybe my concepts
>>are still somewhat simplistic, but is this not a cumbersome case of
>>discovering current nodes and antinodes along a wire being fed with
>>RF?

>That's how it seems to me, too. The only way uneven heating could
>occur is for the velocity factor to be slow enough that the string of
>beads represents a significant portion of a wavelength along the
>outside of the cable.

>>Surely we expect beads fortunate enough to be placed at a
>>*common mode* current node not to heat up at all?

>"Node" meaning "minimum", yes, if the minimum is low enough. But then
>they won't be accomplishing anything, either.

According to the Amidon formula, it's the voltage across the turn,
not the current, that determines core flux.  I'm not sure I fully
understand this, but it's the basis I use for determining flux levels
in toroids.

Maybe the problem isn't this complicated.  Assuming the balun is hung
from the center of an antenna, it might be a simple matter of heat
rising.

73,
Jack  WB3U


From [e-mail] Tue Apr 09 17:00:21 1996
From: [e-mail] (John Chapman)
Newsgroups: rec.radio.amateur.antenna
Subject: Re: Larson 2/70 open coil ant
Date: 8 Apr 1996 13:32:07 GMT
Message-ID: <4kb4gn$[e-mail]>
References: <4j92jd$[e-mail]>

Tom Lewis ([e-mail]) wrote:
: FYI
: I recently purchased a Larson 2/70 dual band OPEN COIL antenna for my
: car.  When installed using the larson magmount, I discovered the antenna
: was resonant above both 2 meters and 70 centimeters!  The SWR was 2.2


   I recently ordered (from HRO) a Larson 2/70 for my motohome, expecting
to get the closed model like i have used on my minivan for 5 years.
  When I got the open (cell type) model, I called HRO and was told that
the open model is the only one Larson is supplying now.
  I went ahead and installed it (using home made L bracket). My Yeasu swr
meter indicates 1.3 to 1 in middle of both bands. Old one is 1.1 to 1 at
same freq.
  With minivan and motorhome parked next to each other, even with the 5 ft
height advanage, the one on motorhome is about .5 s unit poorer both xmit
& rec've  in 3 dif directions using the same xciever and power source.
 Bottom line; I don't believe the two ant's are equivent and for longer trips,
I may exchange the one for the other.



From [e-mail] Tue Apr 09 17:00:23 1996
From: [e-mail] (Graham Seale)
Newsgroups: rec.radio.amateur.antenna
Subject: Measuring Common Mode Voltages
Date: Fri, 05 Apr 1996 08:19:27 GMT
Distribution: world
Message-ID: <[e-mail]>
Reply-To: [e-mail]

Hello Radio Folk
This derives from the G5RV thing, the thread having clearly moved on.

To measure a common-mode voltage - this is what I tried.
Use a small toroid with a single centre tapped winding. Ensure there
are sufficient turns and permeability to make an inductance that has
a reactance more than than (say) ten times the balanced line impedance.
Also, the core material characteristic must allow alternating field
storage at the frequency in use.

Connect it across the balanced line. A line carrying only balanced
currents will cause the centre tap RF voltage to be precisly mid-way
between the voltage at the line conductors.  These voltages being 180
degrees out of phase means the centre tap voltage will be zero relative
to any nearby balanced ground. Any net RF voltage measured at the tap
relative to ground is common mode.

Hope this helps..

73's de G4WNT


--
Graham Seale


From [e-mail] Tue Apr 09 17:00:23 1996
From: [e-mail] (W8JI  Tom)
Newsgroups: rec.radio.amateur.antenna
Subject: Re: metal box for tuner??
Date: 5 Apr 1996 08:29:39 -0500
Message-ID: <4k3783$[e-mail]>
References: <[e-mail]>

In article <[e-mail]>, [e-mail] (James E.
Bromley) writes:

>Now I know why my trusty, old Heathkit SA-2060 has copper-plating
>on its baseplate and lid.
>
>Of course, this still doesn't answer the question of tuner losses.
>After monitoring *that* discussion here, I have adopted a policy
>of  "Don't Ask, Don't Tell, Don't Pursue".  ;-)
>
>Jim Bromley, W5GYJ

Yep, good idea! Anyway, being a ex-contract design engineer for Heath, I
can sum up why it had a .00015 inch copper flash finish instead of zinc.

Marketing.

After all, people loved the DX100 chassis and always asked why the Apache
didn't have a "real" copper chassis! That marketing guy now works for
stereo manufacturers. He's probably the person responsible for oxygen free
copper cables with gold flash teflon connectors for the stereos in car's
that jump.

He also designed oil pan gaskets for Harley-Davidson.

73 Tom


From [e-mail] Tue Apr 09 17:00:24 1996
From: [e-mail] (James E. Bromley)
Newsgroups: rec.radio.amateur.antenna
Subject: Re: metal box for tuner??
Date: 5 Apr 1996 04:53:01 -0700
Message-ID: <[e-mail]>
References: <[e-mail]> <4jue1c$[e-mail]>


>>   [e-mail] ( Lee Carkenord    KA0FPJ) wrote:

>>In the 1996 ARRL Handbook, page 22.60 is the following statement:

>>"Do not build your antenna tuner in a steel box! A steel enclosure
>>can raise a solenoidal coils losses sky high."

>>Is this advice correct??  Why have I never been cautioned about
>>this before??  Comments, please!!!

> [e-mail] (WB3U) writes:

>Wish I'd known this before I bought a Dentron tuner.  Omigosh, I just
>realized my HF amplifier is in a steel cabinet too!  Yikes, so's my
>transceiver!  This is worse than Mad Cow disease!  ;)

Now I know why my trusty, old Heathkit SA-2060 has copper-plating
on its baseplate and lid.

Of course, this still doesn't answer the question of tuner losses.
After monitoring *that* discussion here, I have adopted a policy
of  "Don't Ask, Don't Tell, Don't Pursue".  ;-)

Jim Bromley, W5GYJ
Glendale, AZ



From [e-mail] Tue Apr 09 17:00:26 1996
From: [e-mail] (WB3U)
Newsgroups: rec.radio.amateur.equipment,rec.radio.amateur.antenna
Subject: Re: MFJ Artificial Ground
Date: Sun, 07 Apr 96 00:38:34 GMT
Message-ID: <4k7394$[e-mail]>
References: <4k43ol$[e-mail]> <4k4tth$[e-mail]>

Gary's article hasn't appeared on my news server yet, but I would like
to post some preliminary comments based on the text Tom quoted.

   [e-mail] (W8JI  Tom) wrote:
>(Gary Coffman) writes:

>>Tom's mistake is trying to use transmission line theory on what is
>>*not* at this point functioning as a transmission line.

The concept of 1/4 and 1/2 wave lines applies equally well to single
conductors.  This is evidenced by the use of 1/4 wave single-conductor
decoupling stubs in microwave circuitry.

>>It is, instead, an unintended end fed 1/2-wave antenna. Now while it
>>is true that the ends of such an antenna are voltage maxima, that's
>>because the ends are very high impedances, and thus not much current
>>will "turn the corner" to excite this "antenna", so there won't be
>>much high voltage down at the shack end.

This paragraph entirely contradicts itself in trying to prove that a
1/2 wave conductor will isolate antenna currents from the transmitter.
First it states that because the 1/2 wave shield simulates a 1/2 wave
end-fed antenna, the voltage and impedance on both ends will be high.
Then it says that because little current will flow, one end will
actually be low.

>>OTOH, a 1/4-wave will be a low feed impedance at the antenna, thus
>>lots of current will divert down toward the shack, and will express
>>itself as a high voltage at the high impedance of the other end.

Another contradiction; this paragraph says the same thing about the
1/4 wave shield that the previous paragraph said about the 1/2 wave -
that one end will have a higher impedance than the other.  This time
it's true, but the rest of the explanation is incorrect.

Yes, there is a low feedpoint impedance at the antenna, but it's
created by the 1/2 wave dipole, not the shield.  The 1/4 wave shield
looks like a high impedance due to reflections from the other end,
therefore current does not flow toward the shack as claimed.

>>(And the other end *will* be a high impedance because the current
>>can't penetrate the coax shield or the transmitter case to "close
>>the loop" with the driving source.

This is also incorrect.  The RF voltage at the antenna is a free agent
that is attracted to *all* conductive objects with a lower potential.
That includes any object connected to earth or to the B- of the
transmitter, as well as any object large enough to convert the current
into radiated energy.  The latter is the "electrical mass" that Tom
often refers to.

Let's analyze the transmitter in this regard.  If it was totally
isolated from earth, the outer chassis would "float" at some RF
potential due to the connection between the chassis and the outer
shield of the coax.  This would be true regardless of shield length,
because in practice even the input impedance of a 1/4 wave shield
(at the antenna) won't be infinitely high and some current will flow.

However, the trasnmitter is not isolated from earth.  It is coupled to
earth by means of AC lines and other equipment.  Even if this coupling
is very loose, it is sufficient to pull the chassis to near-ground
potential due to the isolation provided by the 1/4 wave shield.

As a side note, earth is likely to be more effective at this than even
a direct connection to the inside of the transmitter.  Unlike earth,
the effectiveness of B- as a return path for common-mode current is
determined in part by the relative phase between current leaving the
transmitter and current arriving at B- by way of the shield.

It's also my belief that the outer chassis of a transmitter is not
well-isolated from internal grounds as previously claimed, and that
phase and amplitude differences are the real reason the shield current
cannot be cancelled by merely returning to B-.  At the very least,
this lack of isolation appears to be confirmed by the fact that RF on
the outer chassis will often create internal equipment malfunctions.

>>Whether the transmitter case is connected to Earth or not is largely
>>irrelevant as well.)

This statement can only be accepted if one believes that RF voltage
is not attracted to earth.

73,
Jack  WB3U


From [e-mail] Tue Apr 09 17:00:27 1996
From: [e-mail] (Bill Poston)
Newsgroups: rec.radio.amateur.antenna
Subject: REQUEST SUGGESTION FOR HF ANT
Date: Tue, 09 Apr 1996 18:56:50 GMT
Message-ID: <[e-mail]>

I am about to purchase a HF ant. I would appreciate suggestions as to what
would be the best value in a HF ant.

Thanks.

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Bill            <[e-mail]>
Marietta, Ga.
================== THIS TOO, SHALL PASS ==================


From [e-mail] Tue Apr 09 17:00:28 1996
From: [e-mail] (Raymond Sarrio)
Newsgroups: rec.radio.amateur.antenna
Subject: Sell your ant/towers/rotors @ http://www.csz.com/sarrio.html
Date: 6 Apr 1996 06:31:25 GMT
Message-ID: <[e-mail]>

The Raymond Sarrio Company's Ham Radio WWW site is proud to announce a
FREE Ham Radio classified advertising page at
http://www.csz.com/sarrio.html.

This new classified section will allow Hams to search for equipement with
the help of a search engine--no need to scroll through 100's of listing
before you find that special piece of gear. Plus, when you find the gear
your interested in, each listing comes with point-and-click e-mail access,
direct to the Ham that listed the item.

For those Hams with gear to sell, take note! It is absolutely FREE to list
your equipment within Ham Classifieds, and there will be no posting time
delays.  Your posting will go on-line, in our classified search engine,
immediately. All you need do is fill out a simple forms page, and upon its
(point-and-click) submission, your "For Sale" advertisement is on-line
within 1 hour. I will be purging the classified listing initially about
once every month, but that timeline will shorten as our classified numbers
go up. Give it a try, and let me know how you like it. 73's Ray
--
The Raymond Sarrio Co. a full feature Ham Radio Storefront on tth WWW at http:
//www.csz.com/sarrio in association with Brillar Enterprises http://win-win.co
m/brillar an Extensive Discount CD-Rom Catalog!



From [e-mail] Tue Apr 09 17:00:29 1996
From: [e-mail] (Don Phelps)
Newsgroups: rec.radio.amateur.antenna
Subject: Re: Simple 2 Meter Gone Wrong
Date: Thu,  4 Apr 1996 15:43:00 GMT
Message-ID: <[e-mail]>
Distribution: world
References: <[e-mail]>

 soldered
 DRD> both the braid & center conductor to the wire; the solder points are
 DRD> about 1/2" apart.

Try cutting the antenna wire between the solder points, so that
the shield is connected to one side, and the center conductor is
connected to the other side of the dipole.

Don, N6MCE



... [e-mail]

___ Blue Wave/QWK v2.20 [NR]


From [e-mail] Tue Apr 09 17:00:30 1996
From: [e-mail]
Newsgroups: rec.radio.amateur.antenna
Subject: Re: SSB DX antennas for 2M
Date: 7 Apr 1996 06:46:01 -0700
Message-ID: <4k8gup$[e-mail]>
References: <4jmqmc$[e-mail]>
Reply-To: [e-mail]

        For 2m dx, go for forward gain, f-b ratio is more important during contests.
A bigger problem for you may be height. I'm at 30 ft. which is about minimum f
or dx
performance. Less will let you ragchew the locals but you won't hear the weak
ones.
        What part of Arizona? I'm in north Scottsdale, 2m station is a wreck, so I'm
off the air for a while.

Jim N7TCF
[e-mail]

In <4jmqmc$[e-mail]>, [e-mail] (Ron Ries) writes:
>I am considering a 2m horizontally polarized gain antenna for 2M DX. I
>live in an antenna restricted area but could get away with 12 foot boom.
>Have considered the KLM, M2, and Lightning Bolt 10 element quad. Any
>comments on performance or other factors that would influence a selection?
>
>Any other suggestions of other mfrs?
>
>73
>Ron
>KG7LR
>--
>Arizona Dreamin'
>



From [e-mail] Tue Apr 09 17:00:31 1996
From: [e-mail] (RICKCRIDER)
Newsgroups: rec.radio.amateur.antenna
Subject: Tower Restrictions....Help Please....
Date: 6 Apr 1996 23:18:53 -0500
Message-ID: <4k7fnd$[e-mail]>
Reply-To: [e-mail] (RICKCRIDER)

I'm anticipating potential problems with tower installation plans on my
property which is located in a local Historic District.    The towns
zoning manual as well as the Historic District Commissions guidelines do
not address towers directly.  I think I can handle the Zoning board.
The Historic District Commission could present more of a problem as their
guidelines are more cosmetically and aesthetically oriented and therefore
more open for loose interpretation, (and none of the board members are
hams and will problably think that my proposed tower (72 ft.) is
atrocious).    Any similar battles fought and won or lost out there?
Also,  any idea as to what the ARRL is able to offer in defense of towers?
All ideas appreciated.  I've got about 30 days to formulate my strategy.
Cordially:
Rick Crider
KD4FXA
Monroe NC
Asst.  EC / Union County NC
<[e-mail].>


From [e-mail] Tue Apr 09 17:00:32 1996
From: [e-mail] (Jim Weir)
Newsgroups: rec.radio.amateur.antenna
Subject: Re: Tower Restrictions....Help Please....
Date: Mon, 08 Apr 1996 14:49:15 GMT
Message-ID: <4kb91o$[e-mail]>
References: <4k7fnd$[e-mail]>

[e-mail] (RICKCRIDER) shared the following priceless pearls
of wisdom:

>I'm anticipating potential problems with tower installation plans on my
>property which is located in a local Historic District.
Let me see, since historic districts are generally some lots of years
old, you bought into the district and now want to change the rules to
suit yourself.  Did I get that about right?  Sort of like the folks
that bought real cheap land under the airport approach path and now
want to shut down the airport because of the damned noise.

>The towns
>zoning manual as well as the Historic District Commissions guidelines do
>not address towers directly.  I think I can handle the Zoning board.

I hope so, because most of the zoning board members are your
neighbors.  Most of them serve without pay strictly as a public
service to preserve the charm of the neighborhood as it was planned.
You can "handle" them?  Don't flatter yourself, bucko.  Most of these
folks have served more years than you've had a ticket and they can
smell this kind of manure wagon a mile away.


>The Historic District Commission could present more of a problem as their
>guidelines are more cosmetically and aesthetically oriented and therefore
>more open for loose interpretation, (and none of the board members are
>hams and will problably think that my proposed tower (72 ft.) is
>atrocious).

So would I, and I've had my ticket and been in the business for almost
forty years.  You want to put up a monster tower?  Go out into the
boonies and buy a farm where you can enjoy it to your  heart's content
without imposing your aesthetics on your neighbors.

>Any similar battles fought and won or lost out there?

Lord, for the sake of neigborhoods everywhere, I truly hope so.


>Also,  any idea as to what the ARRL is able to offer in defense of towers?
>All ideas appreciated.  I've got about 30 days to formulate my strategy.

Sell.  Take your profit and buy a parcel without zoning restrictions.
If they try and impose them AFTER THE FACT, I'll stand up and scream
foul with the best of them.  You bought knowing full well the
consequences.  Don't run crybaby telling everybody how the big mean
government is beating up on you.  Small town government is your
neighbors trying to keep the neighborhood from looking like a war
zone.

Jim


Jim Weir VP Engineering | You bet your sweet patootie I speak for the
RST Engineering         | company.  If I don't, ain't nobody gonna.
Grass Valley CA 95945   |
http://www.rst-engr.com | AR Adv WB6BHI--FCC 1/C phone--Cessna 182A N73CQ
[e-mail]        | Commercial/CFI-Airplane/Glider-----A&P Mechanic



From [e-mail] Tue Apr 09 17:00:35 1996
From: [e-mail] (RICKCRIDER)
Newsgroups: rec.radio.amateur.antenna
Subject: Re: Tower Restrictions....Help Please....
Date: 8 Apr 1996 22:02:10 -0400
Message-ID: <4kcgf2$[e-mail]>
References: <4kb91o$[e-mail]>
Reply-To: [e-mail] (RICKCRIDER)

To the group:
The following original query from myself and the needless response from
Jim
Weir is but a perfect example of how a newsgroup that is supposed to
foster
amateur radio can be so discouraging to hams everywhere.   My responses to
his remarks, marked 'RC', are in an attempt to explain my plight.   I will
not allow him to engage me in a flame throwing contest on this board.

Subject: Re: Tower Restrictions....Help Please....
From: [e-mail] (Jim Weir)
Date: Mon, 08 Apr 1996 14:49:15 GMT
Message-ID: <4kb91o$[e-mail]>

[e-mail] (RICKCRIDER) shared the following priceless pearls
of wisdom:

>I'm anticipating potential problems with tower installation plans on my
>property which is located in a local Historic District.

JW: >>Let me see, since historic districts are generally some lots of
years
old, you bought into the district and now want to change the rules to
suit yourself.  Did I get that about right?  Sort of like the folks
that bought real cheap land under the airport approach path and now
want to shut down the airport because of the damned noise.

RC:>>>Jim, I'm afraid you are off track.   The homes here are quite old,
though the area was declared a Historic District in 1984, after I had
purchased my home here.   In fact, I was one of the leaders of the group
that
petitioned and chartered the District.   Even served 4 years on the
Historic
District Commission,  3 years as chairman.   Therefore, having seen how
the
'system' works from the inside,  I know how the District Guidelines that
the
City Council stuck us with are so loosely written and the interpretation
of
those guidelines are subject to the whim of the evening.

>The towns
>zoning manual as well as the Historic District Commissions guidelines do
>not address towers directly.  I think I can handle the Zoning board.

JW:>>I hope so, because most of the zoning board members are your
neighbors.  Most of them serve without pay strictly as a public
service to preserve the charm of the neighborhood as it was planned.
You can "handle" them?  Don't flatter yourself, bucko.  Most of these
folks have served more years than you've had a ticket and they can
smell this kind of manure wagon a mile away.

RC:>>>Jim, confused even more I believe.   The Zoning staff are paid city
officials and are not my neighbors.   Most, if not all of them live in the
suburbs with the golf courses and their protective covenents.  In fact,
the
interim Zoning administrator lives in another town altogether.   However,
the
City Council members are elected officials, though they do receive a small
compensation for their time.   You are partially right in one respect,
the
City Council has served way too long and are much too busy protecting the
strip shopping centers that they own.

>The Historic District Commission could present more of a problem as their
>guidelines are more cosmetically and aesthetically oriented and therefore
>more open for loose interpretation, (and none of the board members are
>hams and will problably think that my proposed tower (72 ft.) is
>atrocious).

JW:>>So would I, and I've had my ticket and been in the business for
almost
forty years.  You want to put up a monster tower?  Go out into the
boonies and buy a farm where you can enjoy it to your  heart's content
without imposing your aesthetics on your neighbors.

RC:>>>  Forty years?  Izat right?  In that you are 52 years old,  I assume
you earned your first ticket at the age of 12.   If that is correct, then
I
hold great respect for you for that accomplishment.   We have a brilliant
12
year old in our local club and I hope his current mindset doesn't degrade
to
that of yours by the time he is 52.   'Monster' tower?   72 feet,
including
mast?   Geez, its barely taller than my house.   I wonder what adjective
you
would use to describe the microwave relay towers that dot the horizon,
visible from my balcony.   Incidentally, I do have a small farm in the
boonies, though I don't live on the farm nor do I keep any radio equipment
there, thus, a tower on the farm would be quite useless.  The farm animals
aren't hams, though they possess more intelligence than some hams I've run
across.

>Any similar battles fought and won or lost out there?

JW:>>Lord, for the sake of neigborhoods everywhere, I truly hope so.
RC:>>>Not worthy of comment.

>Also,  any idea as to what the ARRL is able to offer in defense of
towers?
>All ideas appreciated.  I've got about 30 days to formulate my strategy.

JW:>>Sell.  Take your profit and buy a parcel without zoning restrictions.
If they try and impose them AFTER THE FACT, I'll stand up and scream
foul with the best of them.  You bought knowing full well the
consequences.  Don't run crybaby telling everybody how the big mean
government is beating up on you.  Small town government is your
neighbors trying to keep the neighborhood from looking like a war
zone.

RC:>>>Well, Jim, I did buy without ZONING restrictions as they relate to
amateur radio.   With your age and self proclaimed experience, seems that
you
would be aware of PRB-1, (Federal Register: 50 FR 38813), passed by the
FCC
on September 19,  1985, that, among other things,  states that any local
ordinances that preclude amateur radio are in direct conflict with Federal
objectives and must be pre-empted, and further states that any local
ordinances must be crafted to accommodate reasonable amateur
communications.
My proposal calls for my tower in the rear yard, screened by mature trees.
(Opposite side of the house from my radio equipment.)  Asking for a tower
permit  right outside my window, on the street side, could be considered
an
unreasonable request. The Historic District commission members would not
be
expected to be aware of a Federal regulation of such narrow scope,  and I
know from experience on the board how loosely the guidelines can be
interpreted to suit any members personal taste.  I want to 'politely'
bring
this to their attention, so as not to rub their noses in Federal
rulemaking
proceedures,  and bring amateur radio to them in a positive manner.

Jim, in summary please get your facts straight prior to hurling flames
around
the globe at me.   I will not respond to any more of your mindless
opinions
on this board.   Should you have further for me, please kindly direct it
to
my email address.  And, take your Prozac and Valium one half hour prior to
signing on.

Cordially:
Rick Crider
<[e-mail]>
North Carolina


From [e-mail] Tue Apr 09 17:00:36 1996
From: [e-mail] (Gary V. Deutschmann, Sr.)
Newsgroups: rec.radio.amateur.antenna
Subject: Re: Tri-Band 144/220/440
Date: Tue, 02 Apr 1996 02:11:21 GMT
Message-ID: <4jq1hm$[e-mail]>
References: <4jct3n$[e-mail]>

Hmmmmmmmmmmmmmmm.  I posted, but don't see it yet, so I'll give it
another go.

The Copper Cactus Multi-band antenna plans are on my web page
http://www.inlink.com/~raiar under amateur radio or direct
"amateur.html"

TTUL - 73+ de Gary - KG0ZP






From [e-mail] Tue Apr 09 17:00:37 1996
From: [e-mail] (CHARLES J. MICHAELS)
Newsgroups: rec.radio.amateur.antenna
Subject: Re: Tribander trap loss?
Date: 7 Apr 1996 22:39:45 GMT
Message-ID: <4k9g7h$[e-mail]>


Tom said -

It would be interesting to see real antennas on a test range. I'd be
willing to bet we'd have some real bones to pick with some advertisers
when it was all over!


Tom,
        That's why QST does not print gain claims in ads.

Charlie, W7XC
--


From [e-mail] Tue Apr 09 17:00:38 1996
From: [e-mail] (Marv Uphaus)
Newsgroups: rec.radio.amateur.antenna
Subject: Re: tuner/balun
Date: 9 Apr 1996 02:59:17 -0400
Distribution: world
Message-ID: <[e-mail]>
References: <4ka8lt$[e-mail]>
Reply-To: [e-mail]

On 8 Apr 1996 05:37:01 GMT [e-mail] (Cecil A. Moore~) wrote:
>The 4:1 balun with no tuner put 1.3 dB more power into
>the dummy load than the tuner with a 1:1 choke.

ICOM lists their AT-180 tuner that goes with the IC-706 as having a 1 dB
insertion loss...  They don't say whether it's a transmit or receive
insertion loss...!!!

Marv, K4BVG...

-----------------------------------------------------------
Even when the experts all agree, they may well be mistaken.
                                  --Bertrand Russell
PGP PUBLIC KEY posted at pgp.mit.edu
-----------------------------------------------------------


From [e-mail] Tue Apr 09 17:00:39 1996
From: [e-mail] (Cecil A. Moore~)
Newsgroups: rec.radio.amateur.antenna
Subject: tuner/balun
Date: 8 Apr 1996 05:37:01 GMT
Distribution: world
Message-ID: <4ka8lt$[e-mail]>

Ran a test today to answer the question: Which radiates
more - a tuner and 1:1 choke into a 300 ohm dummy
load - or no tuner and a 4:1 balun into a 300 ohm
dummy load?

The 4:1 balun with no tuner put 1.3 dB more power into
the dummy load than the tuner with a 1:1 choke. This
was with a fixed 95 watts from the transmitter on 3.8
MHz. Current and voltage into the dummy load were 17%
higher without the tuner in the circuit. The 1:1 choke
with the tuner had about half a dB more loss than the
4:1 balun with the tuner. Presumably, the 1:1 choke
didn't like the 50/300 ohm impedance jump.

73, Cecil, KG7BK, OOTC  (not speaking for my employer)


From [e-mail] Tue Apr 09 17:00:39 1996
From: [e-mail]
Newsgroups: rec.radio.amateur.antenna
Subject: Wanted Info.:: Mookraker Antenna's
Date: Sun, 07 Apr 1996 10:59:25 -0500
Message-ID: <[e-mail]>

Does anybody no were I can get the big moonraker CB antenna's

any help would be appreciated


thank's
-Rick

--
C.M.S
Computers:(Apple, IBM, NEC, DEC, ) Network Products, Hard Drives:(Segate, Conn
ner, Quantum,) Software, Semiconductor, Passive Components, Connectors.....and
 more.
Phone: [phone] M-F 8-6 pm EST
Fax:   [phone]
Email: [e-mail]
Web Page: http://www.xtalwind.net/~alpha1/index.html

*** We buy used and outdated Computer Equipment / Fax us you list ***
=====================================================================


From [e-mail] Tue Apr 09 17:00:40 1996
From: [e-mail] (Guy Teague)
Newsgroups: rec.radio.amateur.antenna
Subject: Re: Wanted Info.:: Mookraker Antenna's
Date: 8 Apr 1996 05:01:49 -0400
Message-ID: <4kaklt$[e-mail]>
References: <[e-mail]>

[e-mail] wrote:
: Does anybody no were I can get the big moonraker CB antenna's

: any help would be appreciated

: thank's
: -Rick
--------

I left one on the top of the barracks at Guantanamo Bay in 1976. Just
tell them I sent you! <g>
--
Regards  73 de  [e-mail]  "They're out there"              K Kesey
Guy      KG5VT  [e-mail]  "Hey don't eat that yellow snow" F Zappa


From [e-mail] Tue Apr 09 17:00:41 1996
From: [e-mail] (Martin Rask)
Newsgroups: rec.radio.amateur.antenna
Subject: Wich 6m antenna to choose ??
Date: 2 Apr 1996 00:00:46 GMT
Message-ID: <4jpqne$[e-mail]>
Reply-To: [e-mail]

Hello all...

Thanks for reading this..

Ißm just going to buy a 6M antenna my biggest problem is just wich one do
i choose ??

We are only allowed to use 200W ERP here in sweden so the antennas won┤t
have to stand much power HIHI.. but i hope they will change the power
amount soon..

Here is some antennas that i have been thinking of

CREATE CL6DX 7el

M2 6M7 7el

CUSHCRAFT A50-6S 6el

CUSHCRAFT A50-5S 5el

CUSHCRAFT 617-6B 6el

I have never worked on 6m so i would really like to know something about
these antennas.. how do they work ?? are they easy to put togeher ?? do
the stand wind and snow ?? and other things ?? have you tried any other
antenna that is better ??

I┤am really looking forward for some answers..

73┤s de SM7VHS /Martin

my email: [e-mail]



From [e-mail] Tue Apr 09 17:00:42 1996
From: Dave Kynor <[e-mail]>
Newsgroups: rec.radio.amateur.antenna
Subject: Wire Antenna Advice
Date: Fri, 05 Apr 1996 08:43:11 +0000
Message-ID: <[e-mail]>

Hello,

I recently moved into a new house and am looking to put a wire
antenna.  I have lots of land and trees around the house and am
wondering whether I would do better to put up an end fed long wire
heading up a hill from the house (the long wire could be VERY long if
desired, or put up an 80 meter dipole whose average
height would be somewhat lower.

Since we are renting the house - I prefer a fairly simple solution.
Also, I am interested in being able to tune the antenna on 80-10m (I
already have an antenna tuner).

I have lots of experience with end fed wire antennas, but not so much
with dipoles.

Any thoughts/comments would be appreciated!

Dave Kynor
WA2JEI


From [e-mail] Sun Apr 14 17:33:56 1996
From: Will Flor <[e-mail]>
Newsgroups: rec.radio.amateur.antenna
Subject: Re: "finite element analysis"for antennas??
Date: 10 Apr 1996 14:59:04 GMT
Message-ID: <4kgibo$[e-mail]>
References: <[e-mail]>

[e-mail] (Anibal Aguirre) wrote:
>Hi friends:
>does anybody know if exists a soft for antenna analisys that use "finites
>elements" method???
>any suggestion will be appreciated.
>TX
>73 from argentina.
>                                               anibal aguirre
>                                                  LU4DVJ
>

No - I've never even heard of anybody using FEA for antenna design.  I'm
moderately familiar with FEA, since I've written FEA software for molecular
modeling/computer-assisted drug design as well as structural and thermal
analysis of trusses, frames, and solids.  Do you mean *structural* design
of antennas, or electrical design?  If the latter, I'd be very interested
if you (or anyone else) could provide a reference to this, as I've never
heard of it!  If you mean *structural* design, any of the common FEA systems
(NASTRAN, MacNeal Schwendler's product - the name escapes me now, Inertia,
etc. should work just fine.)

73 de Will KB9JTT




From [e-mail] Sun Apr 14 17:33:56 1996
From: [e-mail] (W8JI  Tom)
Newsgroups: rec.radio.amateur.antenna
Subject: Re: "floating" the output of a tuner.
Date: 9 Apr 1996 21:07:14 -0400
Message-ID: <4kf1k2$[e-mail]>
References: <[e-mail]>

test


From [e-mail] Sun Apr 14 17:33:58 1996
From: [e-mail] (Roy Lewallen)
Newsgroups: rec.radio.amateur.antenna
Subject: Re: "VISALIA MOBILE ANTENNA SHOOTOUT"
Date: Sat, 13 Apr 96 20:48:30 GMT
Message-ID: <4kp3sv$[e-mail]>
References: <4ko5eo$[e-mail]>

In article <4ko5eo$[e-mail]>,
   Jesse Touhey <[e-mail]> wrote:
>Reminder: Next Saturday (April 20th) W6KKT will be conducting another
>75 meter mobile antenna system field strength trial. Testing will start
>around 9:00am, test freq:3995kc,max antenna height:13.5'tip to ground.
>The location will at the U.S.Towers factory, Visalia Calif. So, If you
>will be attending the Visalia DX convention or in the area April 20th
>come join us and see how your 75 meter mobile antenna system compares
>with some of the best in the country....73s...Jesse (W6KKT)

I'm giving a talk at 9:00 on computer antenna analysis. Looks like people
get to choose whether to see how antennas theoretically work or how they
really work. I know which choice I would have made if I hadn't agreed to
give the talk. Maybe if everyone goes to it I'll get to go too!

Roy Lewallen, W7EL


From [e-mail] Sun Apr 14 17:33:58 1996
From: [e-mail] (Jim Flanders)
Newsgroups: rec.radio.amateur.antenna
Subject: **  Need source of fiberglass tubing and poles **
Date: 8 Apr 1996 19:54:29 GMT
Message-ID: <4kbqtl$[e-mail]>

I found a real neat half wave over half wave 2 meter antenna in the
English "Wireless" magazine.  It is 52" high. On-the-air reports favor
it over my usual 5/8 whip, and it loads real well on 10 meters. I made
a prototype out of wood dowels.

However, I wish to make quite of few of these so it would be more
professional looking (and lighter) if fiberglass.

If anyone knows a source of fiberglass tubing and poles, please e-mail
me, phone me @ 214-612-1103,  and in Dallas I'm on the Plano repeater.
(147.180 +)

Jim  W0oog/5



From [e-mail] Sun Apr 14 17:33:59 1996
From: Greg Limeberry <[e-mail]>
Newsgroups: rec.radio.amateur.antenna
Subject: 10 m Antenna
Date: 13 Apr 1996 00:50:58 GMT
Message-ID: <4kmtpj$[e-mail]>

Could someone give me an opinion and why on the best available
(premanufactured) 10 meter antenna? Also, could you comment on the
vertical antenna?

Thank you in advance,


Greg Limeberry



From [e-mail] Sun Apr 14 17:34:00 1996
From: [e-mail] (Roy Lewallen)
Newsgroups: rec.radio.amateur.antenna
Subject: Re: 20m dipole 60'h or 3el beam at 35'??
Date: Sat, 13 Apr 96 20:50:46 GMT
Message-ID: <4kp417$[e-mail]>
References: <[e-mail]>

In article
<[e-mail]>,
   "John T. Young" <[e-mail]> wrote:
>Any ideas on which would perform better for transmitting and receiving on
>20 meters....a dipole at 60 'high or a 3 el tribander beam (e.g. Cushcraft
>A3S) at 35' high? I can do one or the other but unfortunately not a
>triband beam at 60'. Your thoughts would be much appreciated. 73 de John,
>KI7JB.  P.S. Assume both are aimed in the same direction.

This is just the kind of problem which computer antenna analysis program
are good at answering.

Roy Lewallen, W7EL


From [e-mail] Sun Apr 14 17:34:01 1996
From: [e-mail]
Newsgroups: rec.radio.amateur.antenna
Subject: am antenna
Date: Wed, 10 Apr 1996 18:57:32 GMT
Message-ID: <4kglit$[e-mail]>

I have a ge "super radio" that actually can pick up a ny public radio
am station from western mass without an antenna attached.
there's a hookup on the back for an antenna connection which I'd like
to utilize.
I went to radio shack, but they said they don't sell am antennas!
can anyone recommend an indoor antenna and where to purchase it?

thanks



From [e-mail] Sun Apr 14 17:34:02 1996
From: Kent Winrich <[e-mail]>
Newsgroups: rec.radio.amateur.antenna
Subject: Re: am antenna
Date: Thu, 11 Apr 1996 12:02:14 -0700
Message-ID: <[e-mail]>
References: <4kglit$[e-mail]>

Butchen:

All you need is a good length of wire, and get that wire as high as you
can.  Also, it would be very helpful to attach a ground as well.  (A good
ground would be a COLD water pipe, or a 6' ground rod.)

In my apartment, I use the rain downspouts as an antenna for my GE SR
III.

Kent

[e-mail] wrote:
>
> I have a ge "super radio" that actually can pick up a ny public radio
> am station from western mass without an antenna attached.
> there's a hookup on the back for an antenna connection which I'd like
> to utilize.
> I went to radio shack, but they said they don't sell am antennas!
> can anyone recommend an indoor antenna and where to purchase it?
>
> thanks


From [e-mail] Sun Apr 14 17:34:03 1996
From: Jake Middlebrook <[e-mail]>
Newsgroups: rec.radio.amateur.antenna
Subject: Re: Antenna Modeling Software
Date: Sat, 6 Apr 96 20:14:25 -0500
Message-ID: <[e-mail]>
References: <4jpj3j$[e-mail]> <[e-mail]> <[e-mail]> <[e-mail]>

try ftp.funet.fi ftp site under pub\ham\hf\antenna they have nec mininec
acoupleof miniloop programs and areial
good luck
jake wb4hpf


From [e-mail] Sun Apr 14 17:34:03 1996
From: [e-mail] (CHARLES J. MICHAELS)
Newsgroups: rec.radio.amateur.antenna
Subject: Re: Antenna Modeling Software
Date: 13 Apr 1996 17:52:07 GMT
Message-ID: <4kopk7$[e-mail]>


Ron said -

Another 2cents worth -- I have both EZNEC and NEC-Win and although EZNEC is
DOS based, I find it much more freindly in terms of operational characteristic
s
and find NEC-Win (basic) to be only windows fancy and not as functionally
clean as I would have expected

Ron,
        My EZNEC is windows not DOS .  But perhaps you mean something else.
Charlie, W7XC
--


From [e-mail] Sun Apr 14 17:34:04 1996
From: [e-mail] (Wes Stewart)
Newsgroups: rec.radio.amateur.antenna
Subject: Re: Antenna Modeling Software
Date: Sat, 13 Apr 1996 14:11:43 LOCAL
Message-ID: <[e-mail]>
References: <4kopk7$[e-mail]>

In article <4kopk7$[e-mail]> [e-mail] (CHARLES J. MICHAELS)
 writes:
>From: [e-mail] (CHARLES J. MICHAELS)
>Subject: Re: Antenna Modeling Software
>Date: 13 Apr 1996 17:52:07 GMT


>Ron said -

>Another 2cents worth -- I have both EZNEC and NEC-Win and although EZNEC is
>DOS based, I find it much more freindly in terms of operational characteristi
cs
>and find NEC-Win (basic) to be only windows fancy and not as functionally
>clean as I would have expected

>Ron,
>        My EZNEC is windows not DOS .  But perhaps you mean something else.
>Charlie, W7XC

Charlie,

Do you have a new (Windows) version of EZNEC that I don't know about?
Did I doze off?

73, Wes
>--



From [e-mail] Sun Apr 14 17:34:05 1996
From: [e-mail] (Decibel7)
Newsgroups: rec.radio.amateur.antenna
Subject: Re: Antennas in PVC pipe
Date: 10 Apr 1996 03:37:02 -0400
Message-ID: <4kfoeu$[e-mail]>
References: <4ju7o5$[e-mail]>
Reply-To: [e-mail] (Decibel7)

Greetings,

  i probably am way out of my element but if you do put the wire on the
outside of the pipe, could you fill it with fluid and seal it to keep it
cooler?,




From [e-mail] Sun Apr 14 17:34:06 1996
From: "George J. Molnar" <[e-mail]>
Newsgroups: rec.radio.amateur.antenna
Subject: Re: Antennas in PVC pipe
Date: Wed, 10 Apr 1996 08:17:02 -0600
Message-ID: <[e-mail]>
References: <4ju7o5$[e-mail]> <4kfoeu$[e-mail]>
Reply-To: [e-mail]
To: Decibel7 <[e-mail]>

Decibel7 wrote:
>
> Greetings,
>
>   i probably am way out of my element but if you do put the wire on the
> outside of the pipe, could you fill it with fluid and seal it to keep it
> cooler?,

You COULD, but it probably wouldn't pay. The fluid would work as a dielectric,
detuning the antenna, and probably increasing losses. If your antenna is getti
ng
too hot, it is likely because the wire diameter you've chosen is too small,
or the power applied is excessive.

73

--
George J. Molnar
Highlands Ranch, Colorado
Amateur Radio: KF2T@N0QCU.#NECO.CO.USA.NOAM
http://www.interealm.com/p/gmolnar/index.html


From [e-mail] Sun Apr 14 17:34:07 1996
From: Joe Foor <[e-mail]>
Newsgroups: rec.radio.amateur.antenna
Subject: Re: Antennas in PVC pipe
Date: Sat, 13 Apr 1996 00:43:51 -0700
Message-ID: <[e-mail]>
References: <4ju7o5$[e-mail]> <4kfoeu$[e-mail]>

Decibel7 wrote:
In a message dated 10 Apr 1996 03:37:02 -0400 Decibel7 wrote:

>   i probably am way out of my element but if you do put the wire on the
> outside of the pipe, could you fill it with fluid and seal it to keep it
> cooler?,

That's a fine idea, but unfortunately, one of the advantages of
PVC over copper, for plumbing, is it's low density, wich gives it
poor thermal conductivity. In other words, the PVC will act as an
insulator and more heat will be radiated out from the wire than
will be conducted in to the fluid.

regards,
Joe KF4DYS


From [e-mail] Sun Apr 14 17:34:08 1996
From: [e-mail] (Ed  Buchanan)
Newsgroups: rec.radio.amateur.antenna
Subject: Attic Quad or loop
Date: Mon, 08 Apr 1996 22:52:19
Message-ID: <4kcu1l$[e-mail]>

I have an idea that a person could build a non rotatable loop beam
antenna in their attic.  This antenna would be like an upside down
Delta Loop, using the roof rafters as a support structure for the
loops.  Using the well published Quad formula to determine the size
of the loops.  And spacing of anywhere between .10 to .20 of the
driven element size, and fed with a 1/4 wave 75 Ohm matching stub.
Depending on how long your attic is, you could have a heck of a
signal in one direction.
Ed KN6CL CUBEX CO.



From [e-mail] Sun Apr 14 17:34:09 1996
From: [e-mail] (Jim Flanders)
Newsgroups: rec.radio.amateur.antenna
Subject: Re: Attic Quad or loop
Date: 9 Apr 1996 12:50:13 GMT
Message-ID: <4kdme5$[e-mail]>
References: <4kcu1l$[e-mail]>

I have been doing this since the early 50s.  You can actually get two
directions.  Put the reflector in the middle. then switch the driven
elements for either direction.  If you have a one story ranch, expect
a very high angle of radiation, and a broad pattern.
Jim W0oog/5

In article <4kcu1l$[e-mail]>, [e-mail] says...
>
>I have an idea that a person could build a non rotatable loop beam
>antenna in their attic.  This antenna would be like an upside down
>Delta Loop, using the roof rafters as a support structure for the
>loops.  Using the well published Quad formula to determine the size
>of the loops.  And spacing of anywhere between .10 to .20 of the
>driven element size, and fed with a 1/4 wave 75 Ohm matching stub.
>Depending on how long your attic is, you could have a heck of a
>signal in one direction.
>Ed KN6CL CUBEX CO.
>



From [e-mail] Sun Apr 14 17:34:10 1996
From: [e-mail] (Tom Bruhns)
Newsgroups: rec.radio.amateur.antenna
Subject: Re: Average Current on Ladder-Line
Date: 9 Apr 1996 15:06:59 GMT
Message-ID: <4kduej$[e-mail]>
References: <4kdka6$[e-mail]>

jaeschke ([e-mail]) wrote:
: Cecil:

: I am confused about the equations.  The first obvious point is
: that the currents are RMS values.  The second is that the power
: calculation that you used is based on Z0.  Since the line may
: not be terminated in Z0, is it necessary to use the real part
: of the actual load impedance for this power calculation?  If
: so, then it gets even more complicated since it would be
: necessary to determine the RL from the SWR and the phase
: relationship of voltage and current.

No, the idea is that you have a "forward" power and a "reverse" power in
the line, and if you can find Ifwd and Irev, then you can calc the
forward and reverse powers in the line, knowing Z0 for the line.  Just
Z0*Ifwd^2 and Z0*Irev^2.  The load power must be just the difference
between the forward and reverse powers.  Cecil has indicated there's a
reasonable way to measure Imax and Imin on the line, and it's fairly
easy to show that Z0*Imax*Imin is the difference between forward and
reverse powers, which equals the load power.


--
Cheers,
Tom
[e-mail]


From [e-mail] Sun Apr 14 17:34:11 1996
From: jaeschke <[e-mail]>
Newsgroups: rec.radio.amateur.antenna
Subject: Re: Average Current on Ladder-Line
Date: 9 Apr 1996 12:13:58 GMT
Message-ID: <4kdka6$[e-mail]>
References: <4jrmbe$[e-mail]> <4jtapl$[e-mail]> <[e-mail]> <4jucci$[e-mail]>

Cecil:

I am confused about the equations.  The first obvious point is
that the currents are RMS values.  The second is that the power
calculation that you used is based on Z0.  Since the line may
not be terminated in Z0, is it necessary to use the real part
of the actual load impedance for this power calculation?  If
so, then it gets even more complicated since it would be
necessary to determine the RL from the SWR and the phase
relationship of voltage and current.

Would a different subscript rather than AVG be less
confusing?  How about L for load.

Jim




From [e-mail] Sun Apr 14 17:34:12 1996
From: jaeschke <[e-mail]>
Newsgroups: rec.radio.amateur.antenna
Subject: Re: Average Current on Ladder-Line
Date: 10 Apr 1996 17:03:59 GMT
Message-ID: <4kgplv$[e-mail]>
References: <4kdka6$[e-mail]> <4kduej$[e-mail]>

Tom:

I understand that the current leaving the transmission line is
the difference between the forward current and the reflected
current.  If this is true, then the power to the load is then
IL^2*RL where IL is the difference between the forward and
reflected currents and RL is the resistive component of the
load connected to the transmission line.  Isn't this correct?
Where is my understanding wrong?

Jim




From [e-mail] Sun Apr 14 17:34:12 1996
From: [e-mail] (WB3U)
Newsgroups: rec.radio.amateur.antenna
Subject: Re: Average Current on Ladder-Line
Date: Fri, 12 Apr 96 07:28:30 GMT
Message-ID: <4kl886$[e-mail]>
References: <4k43im$[e-mail]> <4k4tso$[e-mail]> <4kefe7$[e-mail]> <4kjd6f$[e-mail]>

Post / CC by Mail

   Cecil Moore <[e-mail]> wrote:

>Hi Jack, could you describe the "Measures" style tuner. I don't know
>anything about it. It is a commercial unit?

As far as I know, it's just a balanced T (or Pi) driven by a balun.
Dick Measures published the design in one of the magazines some years
back.

73,
Jack  WB3U


From [e-mail] Sun Apr 14 17:34:13 1996
From: [e-mail] (Jim Lill)
Newsgroups: rec.radio.amateur.antenna
Subject: Re: Beam Coordinate Headings for DX..
Date: 8 Apr 1996 11:14:37 GMT
Message-ID: <4kaset$[e-mail]>
References: <4k2h09$[e-mail]>

Dave Perkins ([e-mail]) wrote:
:  I member seeing a chart that had beam headings for DX countries...

There's numberous programs around to do that. MINIPROP has both that
and a MUF/Freq prediction facility. It's on most ham BBS and ftp sites

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Jim Lill         [e-mail]
http://www.vectorbd.com/users/jpll
    wa2zkd@wb2psi.#wny.usa.na



From [e-mail] Sun Apr 14 17:34:14 1996
From: [e-mail]
Newsgroups: rec.radio.amateur.antenna
Subject: Re: Beam Coordinate Headings for DX..
Date: 10 Apr 1996 02:35:55 GMT
Message-ID: <4kf6qb$[e-mail]>
References: <4k2h09$[e-mail]>
Reply-To: [e-mail]

In <4k2h09$[e-mail]>, Dave Perkins <[e-mail]> writes:
> I member seeing a chart that had beam headings for DX countries...For
>example, if you wanted to put your beam to the Faukland Is. , then you
>look at the chart and it tells you what heading to turn your rotator to
>so your beam would be right on him...Im in San Diego, so does anyone know
>where I could get one..??
>
> Thanx,
> Dave KC6ZBE
>

 Dave,
 I haven't seen one in several years. I recall the last one I saw was in Austi
n, Texas
 at a ham radio store. You do know that there are several programs that are
 included on the 'QRZ' CD-ROM that whip those headings onto the screen in
 microseconds right? That seems to be the wave of the future. Save a tree, use
 plastic nonbiodegradable discs. Oh well, it's quicker than spinnin' that dial
.

                                                              Jim


From [e-mail] Sun Apr 14 17:34:15 1996
From: Roger A. Cox <[e-mail]>
Newsgroups: rec.radio.amateur.antenna
Subject: Re: Beam TH3JR
Date: 11 Apr 1996 20:45:49 GMT
Message-ID: <4kjr1t$mqe$[e-mail]>
References: <29KrKJ$00Z@hb9hfn>

Cedric,

The TH3JR has the DE spaced 65 1/8" (1654 mm) from the reflector.
The Director is 74" (1880 mm) from the DE.  If you need more
information, please let me know.

Roger WB0DGF
Hy-Gain


From [e-mail] Sun Apr 14 17:34:16 1996
From: [e-mail] (Tom Bruhns)
Newsgroups: rec.radio.amateur.antenna
Subject: Re: Best Antenna Design Program?
Date: 11 Apr 1996 17:21:40 GMT
Message-ID: <4kjf34$[e-mail]>
References: <4ki7n1$[e-mail]>

Thomas Mahanna ([e-mail]) wrote:

:       What's the best Antenna Design Program for DOS/WIN/OS2?

Best??  Depends on what you want to do!  First, I'd characterize
them more as _analysis_ than design programs, for the most part.
Perhaps Antenna Optimizer and Yagi Optimizer qualify as "design"
programs, but you have to give them a starting point and specify
what you want to optimize, if I'm not mistaken.

I use EZNEC from Roy Lewallen, and I find it generally easy to use
and pretty reliable.  It's a DOS program.  There is a Windows
program that's also based on NEC2 code (like EZNEC is) that
seems (from the demo version) to have capabilities very similar
to EZNEC...maybe someone else can review it and give the vendor's
name.

You can get NEC2 code as freeware, I believe, but then you will be
stuck doing your own input formatting and interpretation of the
tabular output; the others have much simplified inputting and
graphical output.  One advantage is you have access to all the NEC2
features--I believe you can do planes and cylinders in NEC2 that the
other programs don't give you access to...maybe someone else knows
otherwise and can correct me if this is wrong.

--
Cheers,
Tom
[e-mail]


From [e-mail] Sun Apr 14 17:34:18 1996
From: [e-mail] (Rob Whitacre)
Newsgroups: rec.radio.amateur.antenna
Subject: Re: Coax Shield Current
Date: 12 Apr 1996 13:09:49 GMT
Message-ID: <4klkmt$[e-mail]>
References: <4kk6i8$[e-mail]>

In article <4kk6i8$[e-mail]>, [e-mail] says...
>
>I wrote:
>
>: I've seen plenty of electrostatic voltmeters which purport to be able to
>: measure voltage without the presence of current. And my hair is a pretty
>: good qualitative instrument for detecting electric fields on a dry day.
>
>Tom Bruhns pointed out to me that even an electostatic voltmeter requires
>_some_ current to operate. This is of course true. We can't measure any
>phenomenon without extracting some energy from it. This means that any
>attempt to measure voltage will require some amount of current (i.e.,
>movement of charge), and any attempt to measure current will require some
>voltage drop. I don't really think it's important whether the electrostatic
>voltmeter _really_ is measuring potential, electric field, or charge. I
>regard all three phenomena as being equally real. But my statement that the
>electrostatic voltmeter (or my hair) can measure voltage without current is
>incorrect.
>
>Roy Lewallen, W7EL


Roy,

Yes, technically speaking *something* has to be taken away from the
electrostatic potential in order to measure it. But I'll defend your original
statements because by their very nature these electrostatic fields would
collapse if any sort of current flow occured. The existance of a very high
impedance is what allows them to form, and compared to our 50 ohm world, you
could say that in practical terms these sampling devices draw no current.

Rob WB8WQA



From [e-mail] Sun Apr 14 17:34:19 1996
From: [e-mail] (W8JI  Tom)
Newsgroups: rec.radio.amateur.antenna
Subject: Re: Coax Shield Current
Date: 12 Apr 1996 01:18:21 -0400
Message-ID: <4kkp2t$[e-mail]>
References: <4kk6i8$[e-mail]>

In article <4kk6i8$[e-mail]>, [e-mail] (Roy
Lewallen) writes:

> But my statement that the
>electrostatic voltmeter (or my hair) can measure voltage without current
is
>incorrect.
>
>Roy Lewallen, W7EL
>
>

I was about to look for an ad for El-hair, the new antenna measurement
device to go with my new freespace feedline antenna.



From [e-mail] Sun Apr 14 17:34:20 1996
From: [e-mail] (James W. KELLEY)
Newsgroups: rec.radio.amateur.equipment,rec.radio.amateur.antenna
Subject: Re: Coax Shield Current (Was Re: MFJ Artificial Ground)
Date: 9 Apr 1996 17:08:37 GMT
Message-ID: <4ke5il$[e-mail]>
References: <4k43ol$[e-mail]> <4k7394$[e-mail]> <[e-mail]> <4kaua0$[e-mail]>

In article <4kaua0$[e-mail]>,
WB3U <[e-mail]> wrote:
>
>Gary, no offense, but this couldn't be more ambiguous.  Voltage is
>attracted to all unlike voltages.
>
>Also, unless you believe that a charge on an object is imaginary,
>voltage is indeed a substance.  It is the "essential nature" of
>the objects under discussion.  We can feel it, we can see its effects,
>and we can measure it.
>
>73,
>Jack  WB3U

Ben Franklin couldn't have said it any better!














From [e-mail] Sun Apr 14 17:34:21 1996
Newsgroups: rec.radio.amateur.equipment,rec.radio.amateur.antenna
From: [e-mail] (Gary Coffman)
Subject: Re: Coax Shield Current (Was Re: MFJ Artificial Ground)
Message-ID: <[e-mail]>
Reply-To: [e-mail] (Gary Coffman)
References: <4k43ol$[e-mail]> <4k7394$[e-mail]> <[e-mail]> <4kaua0$[e-mail]> <4ke5il$[e-mail]>
Date: Wed, 10 Apr 1996 18:29:37 GMT

In article <4ke5il$[e-mail]> [e-mail] (James W
. KELLEY) writes:
>In article <4kaua0$[e-mail]>,
>WB3U <[e-mail]> wrote:
>>
>>Gary, no offense, but this couldn't be more ambiguous.  Voltage is
>>attracted to all unlike voltages.
>>
>>Also, unless you believe that a charge on an object is imaginary,
>>voltage is indeed a substance.  It is the "essential nature" of
>>the objects under discussion.  We can feel it, we can see its effects,
>>and we can measure it.
>>
>>73,
>>Jack  WB3U
>
>Ben Franklin couldn't have said it any better!

Except that Ben did say it better. He knew that only *charge*
moves, and voltage is what moves it. I expanded on this in
another post, complete with math. We cannot feel voltage,
we can feel currents driven by a potential difference (voltage).
We can't see voltage, we can only see the current flow (spark)
caused by the potential difference. And we can't measure voltage,
we can only infer its presence by measuring the current flow
it causes through a meter movement. All we can directly sense is
charge and its flow, just as we can sense a falling rock. We
can *infer* that something is making it fall, in this case
a gravitational potential, and infer the value of that potential
by the acceleration of the rock, but we can't alter or move
or measure the potential directly.

Gary
--
Gary Coffman KE4ZV          |    You make it,     | Due to provider problems
Destructive Testing Systems |    we break it.     | with previous uucp address
es
534 Shannon Way             |    Guaranteed!      | Email to [e-mail]
Lawrenceville, GA 30244     |                     |


From [e-mail] Sun Apr 14 17:34:23 1996
From: [e-mail] (WB3U)
Newsgroups: rec.radio.amateur.equipment,rec.radio.amateur.antenna
Subject: Re: Coax Shield Current (Was Re: MFJ Artificial Ground)
Date: Thu, 11 Apr 96 06:48:50 GMT
Message-ID: <4kihhj$[e-mail]>
References: <4kdkph$[e-mail]> <4keeoc$[e-mail]>

   [e-mail] (W8JI  Tom) wrote:

>The return path can be either "displacement current" or conduction
>current. There doesn't need to be a ground plane or opposing
>conductor.

Actually, there doesn't need to be a return path either.  This concept
of a "loop" is being misapplied and is absolutely wrong.

Current at the output connector of the transmitter will be *forced* to
be equal and opposite by the fact that a coaxial cable is attached.
Even if the center conductor is disconnected at the antenna, the
current within the coax will still be equal and opposite.  This is
what satisfies Kirchoff in terms of the current supplied by the
opposing poles of the transmitter.

It's also what I meant when I said earlier that RF at the output end
of the coax is a free agent.  It is under no obligation to Kirchoff or
any other law to return to the transmitter, to radiate, to be absorbed
by earth, etc.  It can fail to do all those things and the two poles
of the transmitter will still deliver equal and opposite current.

73,
Jack  WB3U


From [e-mail] Sun Apr 14 17:34:24 1996
From: [e-mail] (Roy Lewallen)
Newsgroups: rec.radio.amateur.equipment,rec.radio.amateur.antenna
Subject: Re: Coax Shield Current (Was Re: MFJ Artificial Ground)
Date: Thu, 11 Apr 96 17:51:54 GMT
Message-ID: <4kjgpu$[e-mail]>
References: <4k43ol$[e-mail]> <4k4tth$[e-mail]> <4k7394$[e-mail]> <[e-mail]> <4kaua0$[e-mail]> <4kdkph$[e-mail]>

In article <4kdkph$[e-mail]>,
   jaeschke <[e-mail]> wrote:
>Jack:
>
>I believe that Gary has a point in that the circuit back to the
>transmitter must be (visibly) completed.  To me this means that
>the current that leaves the transmitter in the center lead of
>the coax must return to the transmitter in some manner.
>Generally, this is throught the shield of the coax.  If it did
>not return, then the negative charge of the electrons leaving
>the radio would leave a positive charge on the case of the
>radio.

The return path is not through the shield, but on its surface. The shield
has two surfaces, inner and outer, and entirely different currents can flow
on each surface. We'd like all the return current to flow on the inner
surface, where its field cancels that from the current on the center
conductor. Current flowing on the outer surface will radiate, just like
current flowing on any other wire.

Roy Lewallen, W7EL


From [e-mail] Sun Apr 14 17:34:25 1996
Newsgroups: rec.radio.amateur.equipment,rec.radio.amateur.antenna
From: [e-mail] (Gary Coffman)
Subject: Re: Coax Shield Current (Was Re: MFJ Artificial Ground)
Message-ID: <[e-mail]>
Reply-To: [e-mail] (Gary Coffman)
References: <4k43ol$[e-mail]> <4k4tth$[e-mail]> <[e-mail]> <4kbeqv$[e-mail]>
Date: Thu, 11 Apr 1996 15:45:38 GMT

In article <4kbeqv$[e-mail]> [e-mail] (WB
3U) writes:
>   [e-mail] (Gary Coffman) wrote:
>
>>Let me try to summarize my case so that we can focus on the exact
>>point of disagreement.
>
>>1) The outside of the coax is not acting as a transmission line,
>>   and thus transmission line theory does not apply.
>
>Wave reflection theory will apply.

Yes, it does, reflection theory is not confined to transmission lines.

>>2) The outside of the coax is acting as a halfwave resonant
>structure, IE antenna, and antenna theory must apply.
>
>Antenna theory based on unterminated lines will not apply.  The 1/2
>wave shield is not unterminated.

It is not terminated in its characteristic impedance, however, so
reflection theory still applies, the standing wave still exists,
and this is antenna current, not transmission line current.

>>3) The standing wave on a halfwave antenna forces the ends to be
>>   voltage maxima.
>
>This is true of both the antenna and the 1/2 wave shield.

Yes.

>>4) Ergo, the ends of a halfwave antenna are high impedance points.
>
>This statement is true, but because of the error in (2), it does not
>apply to the 1/2 wave shield.

The error at 2 is your error. You're trying to apply a special case,
a matched line, to the general case of a mismatched line.

>>5) And finally, a high impedance load driven by a low impedance
>>   source won't accept much current.  Therefore use of a halfwave
>>   coax feeder will limit the amount of RF current conducted down
>>   to the shack end of the coax along the coax's outer surface.
>
>The first sentence is true, but no valid basis for the conclusion has
>been presented.
>
>>Now tell me where any of that is wrong, and we can proceed from
>>there.
>
>In a nutshell, you're mixing absolute and relative terms.  You've used
>"low" when the correct term is "less", and "high" when the correct
>term is "greater".  This has led to incorrect conclusions regarding
>both the 1/2 wave and 1/4 wave shield lengths.
>
>You're also applying theory based on unterminated conductors to a
>shield that is terminated by a finite degree of coupling to earth at
>the transmitter.

You're falling into the trap of implicitly assuming a matched termination
for the currents on the outside of the outer conductor. In fact, Earth is
extremely unlikely to provide a matched termination to this current, wave
reflection will occur, and the behavior of currents and voltages on the
halfwave section will be similar to those found if it were operating in
isolation, IE the normal antenna current standing wave pattern will exist.
Incidentally, that's why a halfwave vertical worked against ground has a
very high base impedance, and you have to tap up on it with a shunt feed
to match a 50 ohm coax to it.

Gary
--
Gary Coffman KE4ZV          |    You make it,     | Due to provider problems
Destructive Testing Systems |    we break it.     | with previous uucp address
es
534 Shannon Way             |    Guaranteed!      | Email to [e-mail]
Lawrenceville, GA 30244     |                     |


From [e-mail] Sun Apr 14 17:34:26 1996
From: [e-mail] (WB3U)
Newsgroups: rec.radio.amateur.equipment,rec.radio.amateur.antenna
Subject: Re: Coax Shield Current (Was Re: MFJ Artificial Ground)
Date: Thu, 11 Apr 96 20:00:42 GMT
Message-ID: <4kjvuc$[e-mail]>
References: <[e-mail]> <4kaua0$[e-mail]> <4kdkph$[e-mail]> <[e-mail]> <4kiuge$[e-mail]> <[e-mail]>

   [e-mail] (Gary Coffman) wrote:

>No, Jim. In an *AC* circuit there is no net charge flow. All
>charges merely oscillate back and forth around their original
>positions in step with the changes in potential.

Gary, explanations like this are the reason your readers are confused,
and perhaps also the reason we are having this discussion.  What
you've said is true, but it falls far short of explaining the flow of
current that Jim asked about.

It is much easier to understand what's happening if it's remembered
that the transmitter has two RF output terminals (poles).  The only
"loop" that must exist in order for current to flow is the current
path internal to the transmitter and through the load.  To satisfy
Kirchoff, the current flow through all internal points and through the
two output terminals must be the same.

What you've missed is that current drawn from those two poles is
forced to be equal and opposite by the inherent nature of the fields
inside the coax.  Therefore, regardless of the load at the far end of
the coax, the load seen by the transmitter itself is *always* balanced
at both poles.  Nothing is attempting to draw more current from one
pole than the other, therefore there is no need for any "return"
current in order to balance the transmitter.  **This condition is
satisfied whenever coax is attached to the transmitter.**

Please stop this nonsense about some sort of external loop that must
be completed.  It is an instinctual concept that does not exist in a
coaxially-fed system.

73,
Jack  WB3U


From [e-mail] Sun Apr 14 17:34:28 1996
From: [e-mail] (WB3U)
Newsgroups: rec.radio.amateur.equipment,rec.radio.amateur.antenna
Subject: Re: Coax Shield Current (Was Re: MFJ Artificial Ground)
Date: Thu, 11 Apr 96 22:40:43 GMT
Message-ID: <4kk9ag$[e-mail]>
References: <[e-mail]> <4kaua0$[e-mail]> <4kdkph$[e-mail]> <[e-mail]> <4kiuge$[e-mail]> <[e-mail]>

      >>[e-mail] (Gary Coffman) wrote:
   >[e-mail] (WB3U) writes:
 [e-mail] (Gary Coffman) wrote:

>>2) The outside of the coax is acting as a halfwave resonant
>>structure, IE antenna, and antenna theory must apply.

>Antenna theory based on unterminated lines will not apply.  The 1/2
>wave shield is not unterminated.

>It is not terminated in its characteristic impedance, however, so
>reflection theory still applies, the standing wave still exists,
>and this is antenna current, not transmission line current.

First, I disntinctly remember an implication by you in a reply to Tom
that the single conductor had no characteristic impedance. Does your
answer above mean that you now accept the statement that it does?

Second, I did not say there would be no standing waves on the shield.
However, regarding standing waves, your misunderstanding of this
mechanism is very evident from your reply to Tom in another post. You
were asked "if I ground the far end of a half wave antenna, the
current maximum STILL occurs in the middle instead of the end?"  Your
answer was "Yes".

What you have failed to consider is that if the terminating impedance
is higher than the surge impedance of the shield, standing waves will
create voltage maximas on the ends of the shield.  If the terminating
impedance is lower than the surge impedance of the shield, standing
waves will create *current* maximas on the ends of the shield.

In between an open and a short, the impedance at the ends of the
shield will be some intermediate value and this is why the 1/2 wave
shield does *not* present the high impedance of an open-ended antenna.
Rather, it reflects the common mode impedance at the transmitter back
to the source.

> The error at 2 is your error. You're trying to apply a special case,
> a matched line, to the general case of a mismatched line.

No I'm not.  You're reading something into my post that I didn't say.
I'm hoping this is because you're beginning to realize that what Tom
and I have been saying is true.  It would be nice to reach a
consensus.  ;)

> You're falling into the trap of implicitly assuming a matched
>termination for the currents on the outside of the outer conductor.

One of my earliest posts in this discussion mentioned standing waves
on the shield.  I *never* said the line was flat.

>In fact, Earth is extremely unlikely to provide a matched termination
>to this current, wave reflection will occur, and the behavior of
>currents and voltages on the halfwave section will be similar to
>those found if it were operating in isolation, IE the normal antenna
>current standing wave pattern will exist.

You're completely missing the fact that the impedance at the ends of a
1/2 wave wire will depend almost entirely on the nature of the
termination and the degree of mismatch.

>Incidentally, that's why a halfwave vertical worked against ground
>has a very high base impedance, and you have to tap up on it with a
>shunt feed to match a 50 ohm coax to it.

If you terminate the far end of the vertical with a resistance to
ground, the base impedance will be reduced accordingly.  That's why
your statement that the shield exhibits the same impedance as a 1/2
wave open-ended antenna is completely untrue.

Gary, at one time you stated that the reason for the high impedance
was that the transmitter represents an open-ended wire.  Now you're
arguing that a 1/2 wave wire will *always* exhibit voltage maximas on
its ends, just like an antenna, regardless of the termination.  This
sounds as though you have no evidence to verify either statement and
you've simply presented them both in order to hedge your bet.  ;)

73,
Jack  WB3U


From [e-mail] Sun Apr 14 17:34:29 1996
From: [e-mail] (CHARLES J. MICHAELS)
Newsgroups: rec.radio.amateur.antenna
Subject: Re: Coax Shield Current (Was Re: MFJ Artificial Ground)
Date: 13 Apr 1996 05:28:38 GMT
Message-ID: <4kne26$[e-mail]>


The current flowing on the outside of the shield may be induced by
asymetry with respect to the two halves of the dipole.
        If the outer shield is grounded before entering the building
containing the transmitter the h/// length between the feed point of
the antenna and the ground determines the impedance seen to current
flow from the feedpoint to earth.  The outer shield is i deed a single
wire transmission line with and AVERAGE impedance determined by its
diameter and length.
Charlie, W7XC
--


From [e-mail] Sun Apr 14 17:34:30 1996
From: [e-mail] (CHARLES J. MICHAELS)
Newsgroups: rec.radio.amateur.antenna
Subject: Re: Coax Shield Current (Was Re: MFJ Artificial Ground)
Date: 13 Apr 1996 18:33:37 GMT
Message-ID: <4kos21$[e-mail]>


The Zo of the coax shield as a single wire line, assuming for
convience that it is roughly vertical, Zo= 60 ( (ln (48L/d)) -1)
where d is diamiter and L is length in same units.  If Zo is
reasonably high compared to earth ground resistance then
The impedance seen from the feedpoint to ground is j Zo tan
(angular length).  If the length is near 90 degrees then this is a
rather large inductive reactance to help reduce leakage from the
feedpoint to flow on the line.

Charlie,  W7XC
--


From [e-mail] Sun Apr 14 17:34:30 1996
From: [e-mail] (WB3U)
Newsgroups: rec.radio.amateur.antenna
Subject: Re: Coax Shield Current (Was Re: MFJ Artificial Ground)
Date: Sat, 13 Apr 96 20:37:55 GMT
Message-ID: <4kpasr$[e-mail]>
References: <4kos21$[e-mail]>

   [e-mail] (CHARLES J. MICHAELS) wrote:

> ... If the length is near 90 degrees then this is a rather large
>inductive reactance to help reduce leakage from the feedpoint to flow
>on the line.

Hmmm, if 360 degrees is one wave and 180 degrees is a half wave, then
90 degrees must be . . . . 1/4 wave!

Gee, where have I heard that before?  <g>

73,
Jack  WB3U


From [e-mail] Sun Apr 14 17:34:33 1996
From: [e-mail] (WB3U)
Newsgroups: rec.radio.amateur.equipment,rec.radio.amateur.antenna
Subject: Re: Coax Shield Current (Was Re: MFJ Artificial Ground)
Date: Sat, 13 Apr 96 05:09:22 GMT
Message-ID: <4knkfh$[e-mail]>
References: <4k43ol$[e-mail]> <4ke5il$[e-mail]> <[e-mail]> <4kihkr$[e-mail]> <4kn142$[e-mail]>

   [e-mail] (Mike McCarty) wrote:

>Voltage is not a substance. It is a name for the UNIT OF MEASURE
>(like "inch") for the ElectroMotive Force (EMF).

No, the Volt is the unit of measure.  Voltage is a synonym for EMF.

Also, I'm not the person who brought the term "substance" into this
discussion and I agree that it sounds odd when it's applied to
voltage. Nevertheless, voltage qualifies because it is the "essential
nature" of the conductors under discussion.  If you disagree with
this, Webster's the guy you want to talk to.

>Voltage is not attracted to anything.

My statement was intended to convey the idea in layman's terms.  From
that perspective, it is not inaccurate and I will continue to use it
when appropriate.  I apologize if you find the wording annoying, but
the statement is useful in describing the cause and effect simply and
in a way that no reader will misunderstand.

>I have never seen the phrase "common mode" used in this sense before.

The current (and thus voltage and impedance) that we were discussing
is antenna current.

73,
Jack  WB3U


From [e-mail] Sun Apr 14 17:34:34 1996
From: [e-mail] (W8JI  Tom)
Newsgroups: rec.radio.amateur.antenna
Subject: Re: Coax Shield Current (Was Re: MFJ Artificial Ground)
Date: 13 Apr 1996 11:36:05 -0400
Message-ID: <4kohl5$[e-mail]>
References: <4knl7o$[e-mail]>

In article <4knl7o$[e-mail]>,
[e-mail] (WB3U) writes:

>
>That would be ideal.  However, it is much more difficult to achieve a
>good RF ground than most people realize.  The best solution is still
>to prevent the current from flowing down the line in the first place.
>
>73,
>Jack  WB3U

Charlie made a good point.

A correctly placed "ground" could help prevent current from flowing down
the line in the first place. It doesn't need to be a perfect ground, or
even a real good one. It does need to be properly placed.

This is commonly done at microwave.

Why are you guys wasting time arguing terms when the problem is with
someone's concept of RF circuit behavior? This seems like a Mexican Hat
dance, or a Snake dance around the real issue. It even snakes all over the
newsgroup in four or five places at once, like that is necessary!

73 Tom


From [e-mail] Sun Apr 14 17:34:35 1996
From: [e-mail] (Tom Bruhns)
Newsgroups: rec.radio.amateur.equipment,rec.radio.amateur.antenna
Subject: Re: Coax Shield Current (Was Re: MFJ Artificial Ground)
Date: 13 Apr 1996 00:55:52 GMT
Message-ID: <4kmu2o$[e-mail]>
References: <[e-mail]>

Gary Coffman ([e-mail]) wrote:

: We cannot directly measure a potential difference, we can only infer
: it indirectly by the charge displacements it causes.

Again agreeing with Gary on this, I'd repeat:  you would have good company
if you believe that potential differences and the fields they imply
are simply mathematical models to explain the motion of charged particles
that we can actually observe.  If you insist on thinking of a field or a
potential difference as "real," I have no trouble with that, but it
also doesn't bother me if you think of it only as a mathematical
abstraction that you use to explain the forces on the things (charged
particles) that we can see.  But I do have a problem about "potentials
attracting" (or repelling) eachother.  It's the charged particles
that interact with eachother through electrostatic and dynamic forces.

--
Cheers,
Tom
[e-mail]


From [e-mail] Sun Apr 14 17:34:36 1996
From: [e-mail] (Mike McCarty)
Newsgroups: rec.radio.amateur.equipment,rec.radio.amateur.antenna
Subject: Re: Coax Shield Current (Was Re: MFJ Artificial Ground)
Date: 13 Apr 1996 01:47:46 GMT
Message-ID: <4kn142$[e-mail]>
References: <4k43ol$[e-mail]> <4ke5il$[e-mail]> <[e-mail]> <4kihkr$[e-mail]>

In article <4kihkr$[e-mail]>,
WB3U <[e-mail]> wrote:

)Gary, you're absolutely right about this and I should have been more
)careful in my comments.  Our limited senses and instrumentation don't
)allow direct measurement of voltage, only its effects.

This has nothing to do with electricity. NOTHING can be detected by any
means other than by its effects.

)This does not mean that voltage is not a substance, however.  I used
)the phrase "essential essence" intentionally, as this is the very
)first definition of "substance" according to my copy of Webster's.

Voltage is not a substance. It is a name for the UNIT OF MEASURE (like
"inch") for the ElectroMotive Force (EMF).

)Also, your reply doesn't respond to my statement that voltage is
)attracted to all unlike voltages.  Are you disputing this or is it
)actually a similar disagreement regarding definitions?  I reread your
)previous post, but I'm still not sure.

Voltage is not attracted to anything.

)Incidentally, unless I'm missing some of your articles, I haven't seen
)a reply to either of my posts discussing the impedance of the
)transmitter chassis (one was the article quoting the Antenna
)Handbook).  The common mode impedance of the chassis is one of the
)basic issues behind our disagreement regarding the correct shield
)length.  Have you changed your position on this?
)
)73,
)Jack  WB3U


I have never seen the phrase "common mode" used in this sense before.

Mike
--
----
char *p="char *p=%c%s%c;main(){printf(p,34,p,34);}";main(){printf(p,34,p,34);}

I don't speak for DSC.         <- They make me say that.


From [e-mail] Sun Apr 14 17:34:38 1996
From: [e-mail] (Mike McCarty)
Newsgroups: rec.radio.amateur.equipment,rec.radio.amateur.antenna
Subject: Re: Coax Shield Current (Was Re: MFJ Artificial Ground)
Date: 13 Apr 1996 01:44:53 GMT
Message-ID: <4kn0ul$[e-mail]>
References: <4k43ol$[e-mail]> <[e-mail]> <4kaua0$[e-mail]> <4kdkph$[e-mail]>

In article <4kdkph$[e-mail]>,
jaeschke  <[e-mail]> wrote:
)Jack:
)
)I believe that Gary has a point in that the circuit back to the
)transmitter must be (visibly) completed.  To me this means that
)the current that leaves the transmitter in the center lead of
)the coax must return to the transmitter in some manner.
)Generally, this is throught the shield of the coax.  If it did
)not return, then the negative charge of the electrons leaving
)the radio would leave a positive charge on the case of the
)radio.
)
)Jim

Huh? You seem to think that wires are like water hoses with electrons
squirting out of the end. The electrons go -nowhere-. They don't move.
They vibrate about equilibrium positions. It's the electromagnetic
-wave- which moves. Like waves on water. The water doesn't go anywhere.
Only the waves move.

Mike


--
----
char *p="char *p=%c%s%c;main(){printf(p,34,p,34);}";main(){printf(p,34,p,34);}

I don't speak for DSC.         <- They make me say that.


From [e-mail] Sun Apr 14 17:34:39 1996
From: [e-mail] (WB3U)
Newsgroups: rec.radio.amateur.equipment,rec.radio.amateur.antenna
Subject: Re: Coax Shield Current (Was Re: MFJ Artificial Ground)
Date: Sat, 13 Apr 96 22:37:20 GMT
Message-ID: <4kphsm$[e-mail]>
References: <4k43ol$[e-mail]> <4k4tth$[e-mail]> <4k7394$[e-mail]> <[e-mail]> <4kaua0$[e-mail]> <4kdkph$[e-mail]> <[e-mail]> <4kiuge$[e-mail]>

  jaeschke <[e-mail]> wrote:

Hi Jim,

>If I have a DC source that I connect with one polarity to a
>resistor for a while and then reconnect it with the other
>polarity fot the identical amount of time, I will have a net
>flow of current into the resistor of zero.

It appears that way only if you sum the currents after assigning "-"
and "+" designations.  That's not correct, because this particular
concept of labeling is only appropriate when two phenomena occur
simultaneously.  When that's not the case, only absolute values can be
applied.

73,
Jack  WB3U


From [e-mail] Sun Apr 14 17:34:39 1996
From: [e-mail] (CHARLES J. MICHAELS)
Newsgroups: rec.radio.amateur.antenna
Subject: Re: Coax Shield Current (Was Re: MFJ Artificial Ground)
Date: 13 Apr 1996 05:10:36 GMT
Message-ID: <4knd0c$[e-mail]>


Shouldn't the coax shield be grounded outside the building before
entry?  This often determines the length involved in current frol///
flow on the outside of the coax and the impedance seen at the antena
feed point.
--


From [e-mail] Sun Apr 14 17:34:42 1996
Newsgroups: rec.radio.amateur.equipment,rec.radio.amateur.antenna
From: [e-mail] (Gary Coffman)
Subject: Re: Coax Shield Current (Was Re: MFJ Artificial Ground)
Message-ID: <[e-mail]>
Reply-To: [e-mail] (Gary Coffman)
References: <[e-mail]> <4kiuge$[e-mail]> <[e-mail]> <4kjvuc$[e-mail]>
Date: Fri, 12 Apr 1996 22:54:35 GMT

In article <4kjvuc$[e-mail]> [e-mail] (WB
3U) writes:
>   [e-mail] (Gary Coffman) wrote:
>
>>No, Jim. In an *AC* circuit there is no net charge flow. All
>>charges merely oscillate back and forth around their original
>>positions in step with the changes in potential.
>
>Gary, explanations like this are the reason your readers are confused,
>and perhaps also the reason we are having this discussion.  What
>you've said is true, but it falls far short of explaining the flow of
>current that Jim asked about.

Perhaps it would be useful to discuss precisely what we mean when
we talk about a "flow of current" in relation to AC. What exactly
is flowing if it is not charge? But lets defer that for now.

>It is much easier to understand what's happening if it's remembered
>that the transmitter has two RF output terminals (poles).  The only
>"loop" that must exist in order for current to flow is the current
>path internal to the transmitter and through the load.  To satisfy
>Kirchoff, the current flow through all internal points and through the
>two output terminals must be the same.

Yes, I've been saying that long and loud since the start. The topology
is conservative. Kirchhoff's Law can not be violated.

>What you've missed is that current drawn from those two poles is
>forced to be equal and opposite by the inherent nature of the fields
>inside the coax.  Therefore, regardless of the load at the far end of
>the coax, the load seen by the transmitter itself is *always* balanced
>at both poles.  Nothing is attempting to draw more current from one
>pole than the other, therefore there is no need for any "return"
>current in order to balance the transmitter.  **This condition is
>satisfied whenever coax is attached to the transmitter.**

Ok, so if we believe this, there can be no current flowing down
the outside of the coax because all the current that came up to
the load on the inner had to go back down on the inside of the
outer, and vice versa on the other alternation, because you say
coax *forces* this condition. So now you're left with trying to
explain the source of the current that we know *is* flowing on
the outside of the outer of the coax. Where's the generator for
*that* current if it isn't the transmitter?

>Please stop this nonsense about some sort of external loop that must
>be completed.  It is an instinctual concept that does not exist in a
>coaxially-fed system.

Try again.  Your paragraph 1 above states correctly that all current
leaving the transmitter must return to the transmitter, Kirchhoff's
Law must be obeyed. Your paragraph 2 then states that coax *forces*
the currents on the inner and the inside of the outer to be in balance,
but that leaves I + (-I) = 0 current remaining to flow down the outside
of the coax outer. So you now have to invent another current source in
order to explain the current that *is* flowing down the outside of the
outer, or contend that there *isn't* any current on the outside of the
outer and that this whole thread has been built on a faulty premise
that cannot happen and that there can be no such thing as a hot shack
when we use coaxial feedline.

If you try to say currents spring into existence without a generator,
then you've invented perpetual motion and we can sell that "free"
current flowing down the outside of the coax to the power company
and retire rich, IE you'd be claiming 1+1=3.

[Note: for those not following closely, I know that's not true, it
is merely an implication of Jack's version of how things work. As
a hint for those playing at home, an understanding of what we really
mean by AC "current flow" is a key to understanding what's really going
on.]

Gary
--
Gary Coffman KE4ZV          |    You make it,     | Due to provider problems
Destructive Testing Systems |    we break it.     | with previous uucp address
es
534 Shannon Way             |    Guaranteed!      | Email to [e-mail]
Lawrenceville, GA 30244     |                     |


From [e-mail] Sun Apr 14 17:34:43 1996
From: rob-l@PROBLEM_WITH_YOUR_MAIL_GATEWAY_FILE.superlink.net (Rob-L)
Newsgroups: rec.radio.amateur.antenna
Subject: Directional UHF Using Kitchenware
Date: 12 Apr 1996 05:43:12 GMT
Message-ID: <4kkqhg$[e-mail]>

Anybody catch that Discovery program on satellites, where the guy is
buying pots and steel bowls for use in an amateur sat?

Are there plans floating around on how to make UHF dishes out of
kitchenware?



From [e-mail] Sun Apr 14 17:34:44 1996
From: [e-mail] (Gary Burchett)
Newsgroups: sci.electronics.design,rec.radio.amateur.antenna
Subject: Earth to Sky Omnidir, Commercial?
Date: 14 Apr 1996 18:15:26 GMT
Message-ID: <4krfbu$[e-mail]>

    Looking for a manufacturer that would supply a 900 MHz antenna with a
pattern similar to that of a turnstile array, crossed dipoles over a ground
plane.  Objective is to radio modem to a repeater overhead on a balloon, but
not fixed in position so that a yagi could be pointed to it.  Anyone know who
might take on such a design?

Gary Burchett, VE6BBD
[e-mail]


From [e-mail] Sun Apr 14 17:34:44 1996
From: "Mark S. Conway" <[e-mail]>
Newsgroups: rec.radio.amateur.antenna
Subject: Equipment  for HF ACARS
Date: 10 Apr 1996 00:12:48 GMT
Message-ID: <4keue0$[e-mail]>

What decoding equipment do I need for HF ACARS ???



From [e-mail] Sun Apr 14 17:34:45 1996
From: Kent Winrich <[e-mail]>
Newsgroups: rec.radio.amateur.antenna
Subject: Re: FM Station far away
Date: Thu, 11 Apr 1996 11:59:48 -0700
Message-ID: <[e-mail]>
References: <[e-mail]>

Matthew:

Jeeez it is going to be difficult to do.  Two things are necessary:
Height, and a big antenna.  None of the "powered" antennas are going to
help.  You would need to buy a fairly strong antenna, and get it as high
as you can.  Your receiver would also need to be fairly good as well, to
reject and local FM that are close by.

Can you put up any antenna at all??


Kent

Matthew White wrote:
>
> To Amateur Antenna:
>
>         I currently live in the New York, NY vicinity and would like to be
> able to listen to a radio station that is located in Phildelphia, PA
> -- 96.5FM to be exact...
>
>         Does anyone know how I could listen to this radio station with very
> little ease (i.e., buy a very powerful antenna or something) because
> I do not have the ability to place a tower out my window for I rent
> an apartment currently...
>
>         Any and all help is appreciated!!!
>
> Regards,
> Matter


From [e-mail] Sun Apr 14 17:34:46 1996
From: Esteban Sanchis <[e-mail]>
Newsgroups: rec.radio.amateur.antenna
Subject: Fritzel antenna manufacturer address...
Date: 10 Apr 1996 16:31:27 GMT
Message-ID: <4kgnov$[e-mail]>

      Hi guys

Can somebody give me address of Fritzel in Germany. Thank you in advance.

73'
      Stefan (EA5GMI)



From [e-mail] Sun Apr 14 17:34:47 1996
Newsgroups: rec.radio.amateur.antenna
From: [e-mail] (Jens Goerke DB9LL)
Subject: Re: Fritzel antenna manufacturer address...
Message-ID: <[e-mail]>
References: <4kgnov$[e-mail]>
Date: Fri, 12 Apr 1996 17:07:05 GMT

Esteban Sanchis ([e-mail]) wrote:
>       Hi guys

> Can somebody give me address of Fritzel in Germany. Thank you in advance.

> 73'
>       Stefan (EA5GMI)

KURT FRITZEL Antennen fuer Kurzwellenfunk AG
Postfach 28
Siemensstr. 2
67137 Neuhofen
Tel. [phone]
Fax  [phone]
Germany

Hope that helps,
        Jens, DB9LL
--
Missing coffee error - operator halted.

This message may not be distributed via the Microsoft Network.


From [e-mail] Sun Apr 14 17:34:48 1996
From: [e-mail] (Tommy Karlberg)
Newsgroups: rec.radio.amateur.antenna
Subject: Re: GAP Titan DX
Date: Tue, 09 Apr 1996 16:54:06 GMT
Message-ID: <4kd52n$[e-mail]>
References: <[e-mail]>

[e-mail] wrote:

>Anybody have any experience with the Titan DX.  I have limited
>space and am thinking about this antenna.

>Please Email Reply!
>Thanks Paul

>[e-mail]

Hi!
I helped a friend to put together a Titan this weekend. It works
BEAUTIFUL!!!  No tuning. It outranged two other verticals and had far
less background noise than the longwire. Even though it is not
designed for 160m it was 3 to 4 S-units better on 80, 40, 20 meter and
tuned with the matchbox it still was better than the longwire on 160m.
I'm seriously thinking about replacing my maldol 5-band vertical with
a Titan. But that will have to wait as a present to myself when I have
uppgraded my licence! It sure melps my practice with the CW.

Oh, one more thing, I don't sell antennas!!

73 es cu on the band    SM7PAF / Tommy





From [e-mail] Sun Apr 14 17:34:49 1996
From: "T.D.E." <[e-mail]>
Newsgroups: rec.radio.amateur.antenna
Subject: Re: GAP Titan DX
Date: Wed, 10 Apr 1996 08:03:13 -0400
Message-ID: <[e-mail]>
References: <[e-mail]> <4kd52n$[e-mail]>

Tommy Karlberg wrote:(part..)
> I helped a friend to put together a Titan this weekend. It works
> BEAUTIFUL!!!  No tuning. It outranged two other verticals and had far
> less background noise than the longwire.

Outranged two other verticles? Which two? Any A/B tests done?  -- This
weekend was better than average condx, so you'd need A/B's.


From [e-mail] Sun Apr 14 17:34:50 1996
Newsgroups: rec.radio.amateur.antenna
From: Bob Lewis <[e-mail]>
Subject: Re: Hamsick or Outbacker?
Message-ID: <[e-mail]>
Date: Tue, 09 Apr 1996 08:22:53 -0400
References: <[e-mail]> <4k0ruv$[e-mail]>

pete brunelli wrote:
>
> John Fleming <[e-mail]> wrote:
>
> >Which is a better value?
> >How well does Outbacker Perth work,
> >particularly if I have to put it on back of a Saturn Sedan?
> >Anybody know if the trunk of a Saturn is truly grounded?
> >I know the sides are plastic.
>
> John,
> I have used the Perth for a year and it is a great little antenna.
> However, it needs a solid connection to ground.  The hamstick is no
> different in this regard.  Plan on running a length of braid from the
> mount to the frame.
>
> The Perth is heavier than a hamstick, but covers 80-10.  I know a few
> folks who put 'em on heavy duty VHF mounts and they work ok.
>
> What bands are you planning to be on?
>
> GLI have used the 75, 40, and 20 Hamsticks.  Works great.  I added a 2:1
UnUn (unbalanced to unbalanced broadband matching transformer) at the
base of the antenna inside the fender well in a water-tight box.  I
found the hamsticks (and the hustler) was closer to 25 ohms than 50
ohms.  The UnUn gives me a 1.1:1 match for each hamstick AT RESONANCE.

I have never used the Perth but read somewhere that it has some type of
matching network at the base.

Good luck.



From [e-mail] Sun Apr 14 17:34:51 1996
Newsgroups: rec.radio.amateur.antenna
From: [e-mail] (Steve Ellington)
Subject: Re: Hamsick or Outbacker?
Message-ID: <[e-mail]>
References: <[e-mail]> <4k0ruv$[e-mail]> <[e-mail]>
Date: Tue, 9 Apr 1996 15:10:50 GMT

Better value??? Well, dosen't the Perth cost nearly $300? My hamstick cost
$19.95. I only operate 40 meter cw mobile anyway. I use a little MFJ tuner
at the rig. You may also put a 500pf cap from the base of the antenna to
ground to help match it. That's one thing I don't understand is why these
mobile antennas aren't matched to begin with. After all, the
advertisements don't say anything about this problem.


--
Steve Ellington [e-mail]  Louisville, Ky


From [e-mail] Sun Apr 14 17:34:52 1996
From: [e-mail] (Ross Alexander)
Newsgroups: rec.radio.amateur.antenna
Subject: Re: Hamsick or Outbacker?
Date: 9 Apr 1996 18:28:20 GMT
Message-ID: <4kea84$[e-mail]>
References: <[e-mail]> <4k0ruv$[e-mail]> <[e-mail]> <[e-mail]>

[e-mail] (Steve Ellington) writes:

>That's one thing I don't understand is why these mobile antennas
>aren't matched to begin with.

Isn't the hamstick sold seperately from the mount, and don't vehicles
vary in size and sheet metal content?  It would be a fairly neat trick
to build an antenna that would present a 50+j0 ohm load in every
plausibly imagineable mobile installation and still be an effective
radiator.

BTW, my own experience has been that 15, 20, 40, and 80m hamsticks
load up just fine as delivered; I'm using a tripod-style magmount
centered on the roof of a full size pickup truck (Ford F150).
Obviously YMMV.

>After all, the advertisements don't say anything about this problem.

I've got to assume there's an invisible smiley after this sentence.

regards,
Ross ve6pdq
--
Ross Alexander, ve6pdq  --  [phone]  --  [e-mail]


From [e-mail] Sun Apr 14 17:34:53 1996
From: [e-mail] (Walt Cunningham)
Newsgroups: rec.radio.amateur.antenna
Subject: HELP - Rhombic for amateur bands
Date: 12 Apr 1996 09:35:02 -0700
Message-ID: <4km0nm$[e-mail]>

Can anyone steer me in the right direction for
info on construction of a rhombic antenna field
covering the amateur bands?  I am researching
this for a friend ham operator in WA state who
has 1 acre available (280 ft NSx150 ft EW).
Is this enough area?

Email to:  [e-mail] (Walt Cunningham)
or post to group, please.
daw di-di-daw   di-daw di-daw-dit



From [e-mail] Sun Apr 14 17:34:54 1996
From: Don Huff <[e-mail]>
Newsgroups: rec.radio.amateur.antenna
Subject: Re: HELP - Rhombic for amateur bands
Date: Fri, 12 Apr 1996 15:52:57 -0700
Message-ID: <[e-mail]>
References: <4km0nm$[e-mail]>

Walt Cunningham wrote:
>
> Can anyone steer me in the right direction for
> info on construction of a rhombic antenna field
> covering the amateur bands?  I am researching
> this for a friend ham operator in WA state who
> has 1 acre available (280 ft NSx150 ft EW).
> Is this enough area?
>
> Email to:  [e-mail] (Walt Cunningham)
> or post to group, please.
> daw di-di-daw   di-daw di-daw-dit

    (What does 'X AR' mean?)
An acre is not really enough for a rhombic.  Consider that a decent
rhombic
is two wavelengths minimum per leg.  On 20 meters, that is about 120 ft
per leg.
Also, you want it at least a wavelength high.  Lay out a rhombic on
paper per ARRL antenna book, and see how big it gets!  Plus, you need
FOUR supports, in the
RIGHT places.  Lastly, it is good for only ONE direction (two if
unterminated).

A much better alternative is a 3 element yagi, which takes up a small
fraction
of the room, requires only ONE support, and is ROTATABLE.  They have
about
the SAME gain.  The one thing the yagi doesn't have is wide bandwidth
(an octave
or more for the rhombic).

I have five acres, with several 100+ ft fir trees.  After some pencil
pushing
I concluded that the tower and yagis made much more sense than rhombics!
Even
if the trees were fortuitously in the right locations (they aren't),
just getting
(and keeping) the wire corners up in the trees is not a trivial task.
Also,
any trees in line with the rhombic wires present a real obstacle
problem.  Open
flat land and tall telephone poles are the way to make rhombics, and
this is the way they have historically been sited.  But consider the
cost and effort
of all those supports, when only one support (conveniently close to the
shack)
would hold your stack of yagis, with higher gain, and including 40M!

Good luck,

      73,  Don W6JL


I do have a center fed flattop for 80 CW at 85 feet.  Finding two trees
far
enough apart was fairly easy.

Now, receiving antennas such as Beverages, that is different.  They can
be
practically on the ground,and run in a straight line.


From [e-mail] Sun Apr 14 17:34:55 1996
From: [e-mail] (Ted Fortner)
Newsgroups: rec.radio.amateur.antenna
Subject: Re: HELP: 440mhz (UHF) J-pole Info!!!!
Date: Thu, 11 Apr 1996 15:53:18 -0400
Message-ID: <[e-mail]>
References: <4kf9jl$[e-mail]>

In article <4kf9jl$[e-mail]>, [e-mail] (DAVE M
. SCHERTZER) wrote:

> I've built the 2m (144mhz) copper J-pole fer under
> $5 now, what do I have to do to make a UHF one??
> Now sure of the proper measurements, lengths of the
> copper pipes.....??? Cud I get some info plse reguarding
> this NEW project....Magazine artical? Where,What,How?
>
> Tx alot if I cud get eh info....email: [e-mail]

Check the latest 73 (or one of the very recent ones) for 440 copper pipe
J-pole plans.

73 de KF4GJR
[e-mail]
Ted Fortner


From [e-mail] Sun Apr 14 17:34:56 1996
From: [e-mail]
Newsgroups: rec.radio.amateur.antenna
Subject: info on EHF antennas
Date: 11 Apr 1996 03:38:03 GMT
Message-ID: <4khuqr$[e-mail]>

I'm doing an undergrad thesis on high frequency EHF antennas,
does anyone know of specific sites on the NET, or elsewhere,
on this subject?

Thanks for your help,
   Tom Henwood



From [e-mail] Sun Apr 14 17:34:57 1996
From: [e-mail] (Jim Garver)
Newsgroups: rec.radio.amateur.antenna
Subject: Re: Johnson Matchbox tuners
Date: 8 Apr 1996 19:02:40 GMT
Message-ID: <4kbnsg$[e-mail]>
References: <4k2bi6$[e-mail]>

In article <4k2bi6$[e-mail]>,
Douglas Rhodes <[e-mail]> wrote:
>With only an SWR meter and a Johnson Matchbox, what assumptions could one
>make about the antenna characteristics based on the positions of the
>*tuning* and *matching* controls? e.g., if either *tuning* or *matching*
>need to be zero in order to yield the lowest indicated SWR (not
>necessarily a unity, BTW)...

The Matchbox(tm) will not match impedences much higher than 1500-2000 ohms.
Its easy to get yourself into a feedpoint impedance exceeding 10,000 ohms.
Try matching a 40 meter dipole on 20 meters for instance.
Since you probably won't get into a situation where the impedance of your
antenna is too low for the Matchbox, like less than 30 ohms, you
can expect that your impedance is too high if either of the knobs needs
to be adjusted all the way to its end.  Whether or not its capacitive
or reactive really doesn't matter since you can't match it anyway, but the
knob positions do give clues if you want to go to the trouble to
figure it out.
The easiest thing to do is change the length of the antenna or feedline until
you get the feed impedance down low enough to match.  If you are using
ladder line, as you always should with a Matchbox, then changing the antenna
length will be the most effective.

The above applies to dipoles or other center fed, balanced feed antennas.
A Matchbox-fed, all-band dipole works best when it is not resonant on any
band but its length is such that a high impedance feed is avoided on any
of the bands.  The 105 foot G5RV length is a good example of this.
I've tried all kinds of single and various arrays of ladder-fed dipoles
with my matchbox.  I can almost always get it to match on the WARC bands
as well.  I've found that a dipole cut for the 30 meter band matches well
and gives good patterns on all high bands, for example.
If you are trying to feed high impedance antennas such as an end-fed half
wave with a Matchbox or insist on using low impedance coax to a high impedance
feedpoint, then I must politely suggest that you are mis-applying your
Matchbox and may be better off with one of the cheaper T-match tuners instead.

WA7LDV



--
[e-mail]                             I don't speak for Intel


From [e-mail] Sun Apr 14 17:34:58 1996
From: [e-mail] (Roy Lewallen)
Newsgroups: rec.radio.amateur.antenna
Subject: Re: Ladder line impedance!
Date: Thu, 11 Apr 96 17:55:41 GMT
Message-ID: <4kjh10$[e-mail]>
References: <4kfv93$[e-mail]> <4kgvf1$[e-mail]>

In article <4kgvf1$[e-mail]>,
   [e-mail] (W8JI  Tom) wrote:
>I just ordered some "450"  ohm ladder line. The measured impedance is ~371
>ohms.
>
>I'll contact the vendor, but beware of special non-numbered, mil, or
>commercial feedlines. They aren't what they are advertised to be.

I've got some 62 ohm "RG-58" coax, too.

Tom, that feedline is perfect for a free-space antenna. You lucky stiff!

73,
Roy Lewallen, W7EL


From [e-mail] Sun Apr 14 17:35:00 1996
From: [e-mail] (Roy Lewallen)
Newsgroups: rec.radio.amateur.antenna
Subject: Re: Ladder line length
Date: Tue, 09 Apr 96 16:57:30 GMT
Message-ID: <4ke4rv$[e-mail]>
References: <4k0vjm$[e-mail]> <4k1pi0$[e-mail]> <4k2gob$[e-mail]> <4k9hl2$[e-mail]> <[e-mail]>

In article <[e-mail]>,
   [e-mail] (Graham Seale) wrote:

>I too have tried this. The beads are just one-turn common mode
>chokes. They only start to heat when they saturate. Even with
>very high permeability beads this is quite hard to do.

With low-frequency high-permeability cores (Fair-Rite 70-series or 43),
other loss mechanisms other than saturation cause heating at HF. They'll
get extremely hot at flux levels well below saturation.

>As for the beads heating unevenly when spread out along a feedline
>carrying a large common mode component. Well.... maybe my concepts
>are still somewhat simplistic, but is this not a cumbersome case of
>discovering current nodes and antinodes along a wire being fed with
>RF?

That's how it seems to me, too. The only way uneven heating could occur is
for the velocity factor to be slow enough that the string of beads
represents a significant portion of a wavelength along the outside of the
cable. The beads do have a fairly large amount of inductance and
capacitance, but this amount of velocity slowing still seems surprising. If
it's so, the design of W2DU baluns might be improved when it's taken into
account. But like UFO's, ghosts, and Bigfoot, I've never been able to trap
the phenomenon in the laboratory so I could measure it.

>Surely we expect beads fortunate enough to be placed at a
>*common mode* current node not to heat up at all?

"Node" meaning "minimum", yes, if the minimum is low enough. But then they
won't be accomplishing anything, either.

73,
Roy, W7EL


From [e-mail] Sun Apr 14 17:35:01 1996
From: Kevin Schmidt <kschmidt>
Newsgroups: rec.radio.amateur.antenna
Subject: Re: Ladder line length
Date: 10 Apr 1996 16:55:06 GMT
Message-ID: <4kgp5a$[e-mail]>
References: <4k0vjm$[e-mail]> <4k1pi0$[e-mail]> <4k2gob$[e-mail]> <4k9hl2$[e-mail]> <[e-mail]> <4ke4rv$[e-mail]>

[e-mail] (Roy Lewallen) wrote:
>That's how it seems to me, too. The only way uneven heating could occur is
>for the velocity factor to be slow enough that the string of beads
>represents a significant portion of a wavelength along the outside of the
>cable. The beads do have a fairly large amount of inductance and
>capacitance, but this amount of velocity slowing still seems surprising. If
>it's so, the design of W2DU baluns might be improved when it's taken into
>account. But like UFO's, ghosts, and Bigfoot, I've never been able to trap
>the phenomenon in the laboratory so I could measure it.
>
>73,
>Roy, W7EL

Here is a wild conjecture based on no measurements or experience.

One way to produce a big "velocity factor" is resistive loading. If the
series impedance were entirely resistive instead of inductive
like we want, the form of the current along the line would be

exp(- sqrt(omega R C/2) x (1+j))

where R is the resistance per unit length, C is the capacitance per unit
length and x is the distance along the line. Perhaps people who have
seen the first few beads get hot have used a material not designed for
HF and which has enormous losses. This would get rid of common mode currents
by dissipating the energy rather than reflecting it like we want.

Kevin Schmidt [e-mail]



From [e-mail] Sun Apr 14 17:35:02 1996
From: [e-mail] (CHARLES J. MICHAELS)
Newsgroups: rec.radio.amateur.antenna
Subject: Re: Ladder line length
Date: 12 Apr 1996 19:56:59 GMT
Message-ID: <4kmcib$[e-mail]>


G4WMT said -

In the context of the question being answered at the time (about
using 450 ohm ladder line as a tuned matcher), it did not matter
too much. Thanks for providing the phase velocity of the 450 ohm
line (0.93c). (Its better than I thought!).


        The writer of the inquire said he was using homemade 450 ohm
line.  This is seldom web type.  It is usually made with insulators
of small dimensions separating thew line at considerable intervals.
        The Velocity Factor of such a line is generally close to .95 to
.98.depending on the separation between the separators and to a small
extent on their small cross section.

Charlie, W7XC
--


From [e-mail] Sun Apr 14 17:35:02 1996
From: "Ian White, G3SEK" <[e-mail]>
Newsgroups: rec.radio.amateur.antenna
Subject: Long-wire receive "baluns"?
Date: Fri, 12 Apr 1996 08:59:32 +0100
Distribution: world
Message-ID: <[e-mail]>


Dees anybody know for sure what's inside these "balun" units that are
sold for SWL use with random-length wires? My guess would be an
impedance step-down transformer wound on a piece of ferrite rod.

(To save bandwidth, let's assume we all know that it's not a balanced-
to-unbalanced tranformer.)

73 from Ian G3SEK          Editor, 'The VHF/UHF DX Book'
                          'In Practice' columnist for RadCom (RSGB)
Professionally:
IFW Technical Services     Clear technical English - anywhere.


From [e-mail] Sun Apr 14 17:35:03 1996
From: [e-mail] (K5QQ)
Newsgroups: rec.radio.amateur.antenna
Subject: Looking 4 Cellphone Yagi Antenna's
Date: 13 Apr 1996 16:46:27 -0400
Message-ID: <4kp3r3$[e-mail]>
Reply-To: [e-mail] (K5QQ)

I wonder if anyone has seen Yagi Antenna's that would work on the cell
phone frequencies advertised for sale anywhere.

I provide communications for our local Search and Rescue group and there
are times we need telephone links but are just a bit too far from the cell
phone cites to receive their signals.  Although most of our commo is on
the Ham repeaters or on the State Police SAR frequency, there are some
times when the phones are the only way to get to the people we need to
talk to.  I thought a bit of gain might help me point to a cell Site and
get the link I need.

Anyhow, I called a coupla of the ham radio dealers and they didn't have
any nor any suggestions on where to get one.

Thanks for any help you can provide.

PS  I would appreciate 'leads' as e-mail to [e-mail]

Thanks

Jim


From [e-mail] Sun Apr 14 17:35:04 1996
From: Mio Nome <[e-mail]>
Newsgroups: rec.radio.amateur.antenna
Subject: Looking for OM experienced on half-loop antenna on 80
Date: 10 Apr 1996 22:21:35 GMT
Message-ID: <4khc9f$[e-mail]>

For my 80 m activity I'm using now a half-sloper, but I'm not very satistacted
 from the results. I read about the half-loop antenna. Is there anyone experie
nced on this kind of antenna? Or is there anyone suggesting something to impro
ve the effectiveness of half-sloper?
TNX for helping me.

                                  73 de Aldo IK2ANI









From [e-mail] Sun Apr 14 17:35:06 1996
From: [e-mail] (Graham Seale)
Newsgroups: rec.radio.amateur.antenna
Subject: Re: Measuring Common Mode Voltages
Date: Thu, 11 Apr 1996 10:07:51 GMT
Distribution: world
Message-ID: <[e-mail]>
References: <[e-mail]> <4kefho$[e-mail]>
Reply-To: [e-mail]

In message <4kefho$[e-mail]> WB3U wrote:

> Post / CC by Mail
>
>    [e-mail] (Graham Seale) wrote:
>
> >Use a small toroid with a single centre tapped winding.
>         <snip>
> >Connect it across the balanced line. A line carrying only balanced
> >currents will cause the centre tap RF voltage to be precisly mid-way
> >between the voltage at the line conductors.  These voltages being 180
> >degrees out of phase means the centre tap voltage will be zero
> >relative to any nearby balanced ground. Any net RF voltage measured
> >at the tap relative to ground is common mode.
>
> Hi Graham,
>
> First, won't inductive coupling measure common mode current, not
> voltage?  Also, in the device you described, won't the center tap
> assume whatever voltage it's being measured against, due to stray
> capacitance through the measuring device?  The voltage induced in the
> pickup as a result of current flow through the line will be equal and
> opposite at both ends, therefore the center tap is zero volts
> regardless of the amplitude of induced voltage.  If voltage is
> measured at the center tap, maybe it's due to stray capacitance
> between the pickup and the line.
>

Hi Jack

I know I answered this one in a different way in my direct post, but
I think I now have a better way to say it.

The centre tapped toroid across the balanced line is just a pure
inductance, and wound with enough turns so as not to seriously load
the balanced line. To the line it looks like a high impedance.
The voltages at any point along the balanced line will run a
little current in the toroid coil (90 degree shifted!). In a pure
balanced system the voltage at the centre tap is zero.

You could also use two equal capacitors, or even two equal resistors.
The problem with capacitors is if they are made small enough in
value so as not to seriously load the line, the centre point voltage
will be very difficult to probe without going badly into error from
stray capacitance. It is quite difficult to get capacitors in series
to share the voltage equally without connecting "ballast" resistors
across them.

Using a dual channel scope and using the "ADD" funtion to display
the sum of the voltages (DON'T invoke CH2 "invert") will also do
it I suppose, but I like a simple life. When I was measuring line
balance, it seemed to me that from the centre tap, there was a nice
lump of inductance isolating my measuring meddling from either line.
High impedance RF millivoltmeters (Boonten) or scopes (Hewlett Packard)
are expensive. The toroid gave me nice repeatable results.

Yeah... I know... now the rest of you are going to want the recipe
for the balance measuring jig...more little baluns and toroids etc.

73's fer now
G4WNT.

--
Graham Seale


From [e-mail] Sun Apr 14 17:35:07 1996
From: [e-mail] (W8JI  Tom)
Newsgroups: rec.radio.amateur.antenna
Subject: Re: metal box for tuner??
Date: 12 Apr 1996 09:31:37 -0400
Message-ID: <4kllvp$[e-mail]>
References: <4kl7lc$[e-mail]>

In article <4kl7lc$[e-mail]>,
[e-mail] (WB3U) writes:

>Careful, the same guy invented silver solder.  :)
>
>

You know he did Jack. To solder big chains to wallets and belt buckles.


From [e-mail] Sun Apr 14 17:35:09 1996
From: [e-mail] (WB3U)
Newsgroups: rec.radio.amateur.equipment,rec.radio.amateur.antenna
Subject: Re: MFJ Artificial Ground
Date: Tue, 09 Apr 96 19:47:10 GMT
Message-ID: <4kemch$[e-mail]>
References: <4k43ol$[e-mail]> <4k4tth$[e-mail]> <4k7394$[e-mail]> <[e-mail]>

     [e-mail] (Gary Coffman) wrote:
 >[e-mail] (WB3U)wrote:

>Your server has gone beserk, Jack. There are multiple copies of your
>responses out here now.

That's my fault.  My server eats some posts, others it doesn't.
Sometimes it eats them and then spits them out two days later.  I
think the worst is over, although I've noticed that some incoming
posts never show up (I see the replies but not the original).  I'm
trying to use a public server to recover missing articles, but it
doesn't always work.  My apologies to everyone for the clutter.

>>The concept of 1/4 and 1/2 wave lines applies equally well to single
>>conductors.  This is evidenced by the use of 1/4 wave
>>single-conductor decoupling stubs in microwave circuitry.

>No, that's different. Those stubs are part of the antenna and not
>transmission lines.

Actually, I was thinking about stubs used at the output of a mixer or
driver, connected between the signal path and ground.  Wes has called
me to task on this point though and I think it's better left alone.
The analogy may not hold, due to the proximity of those lines to a
parallel ground plane.

>And because the impedance of the outside of the shield at the other
>(transmitter) end is also high (since the loop isn't closed)

No, it isn't high.  I've explained this in three posts, although I
don't know if you've received them all.  One quotes ARRL literature
which states that the impedance at the transmitter chassis isn't a
high impedance point and that a 1/4 line from the antenna will detune
the system for common mode current.

I basically agree with the rest of your post except for statements
specifically related to this concept.  We're splitting hairs on the
subject of voltage; we both know what it is and what it does.

The power flow you mention does need practical consideration, but I
think it's a side issue.  Regardless of the total power, voltage or
current can be high or low, depending on the impedance.  It's those
components that ultimately cause the symptoms we have to deal with.

Anyway, the transmitter chassis is not at a high impedance point in
the typical ham shack.  We should come back to this after you've had a
chance to read my other posts.  One quotes ARRL material from the
Antenna Handbook, the other is titled "The Transmitter Chassis".  We
won't be able to find mutual ground until we discuss the issues in
those articles.  No pun intended.  ;)

73,
Jack  WB3U


From [e-mail] Sun Apr 14 17:35:10 1996
From: [e-mail] (WB3U)
Newsgroups: rec.radio.amateur.equipment,rec.radio.amateur.antenna
Subject: Re: MFJ Artificial Ground
Date: Fri, 12 Apr 96 16:38:06 GMT
Message-ID: <4km8es$[e-mail]>
References: <4k93s8$[e-mail]> <4kbdf3$[e-mail]> <4kemfn$[e-mail]> <4kklq5$[e-mail]>

Post / CC by Mail

   [e-mail] (Lonnie) wrote:

>I haven't had any problem with RF in the shack even befor I added a
>ground. Since my first post I have added a ground stake and ran a 12
>gauge wire from the ground post of the radio to the ground stake.
>It's 30' long. Now everything I've read says you need to have a
>ground wire as short as possible in order for it to work. In my case
>30' is as short as I can go. This is why I was looking into the
>Artificial Gound. But it really didn't work as I expected it to.

First, what was the purpose of the Artificial Ground?  What were your
performance objectives?

Second, how is your inverted V being fed and how is it tuned on 10-40
meters?  Does it have traps?  Are you using a balun?

>My feed line to the antenna is also 30' long.  The antenna is mounted
>at the eve of the house and goes down at a 45 degree angle to the
>gound with the longest wire coming to with in 4 to 5 feet of the
>ground which then is connected to a insulator and guyed down with
>nylon rope.

Is one leg of the V actually longer than the other, or did you mean
something else?

>Things seem to work fine and I'm able to make contact with almost
>anyone I hear. But like others I want to be able to do the best I can
>with what I have. Does anyone have any suggestions on what I can do
>better, if indeed I need to.

You may not need to.  The trick is to minimize the losses in the feed
system.  Loss can be resistive or it may be the result of radiation
from the feedline.  The latter is only a true loss however if the
operator is certain that energy radiated from the feedline is
unusable.  Depending on many factors, it might occasionally be of
benefit at the receiving end, although it's certainly a pain to deal
with at the transmitter.

Maybe you could describe the antenna system in a little more detail?

73,
Jack  WB3U


From [e-mail] Sun Apr 14 17:35:12 1996
From: [e-mail] (WB3U)
Newsgroups: rec.radio.amateur.equipment,rec.radio.amateur.antenna
Subject: Re: MFJ Artificial Ground
Date: Sat, 13 Apr 96 00:57:29 GMT
Message-ID: <4kn5n8$[e-mail]>
References: <4kemch$[e-mail]> <4kjmsv$[e-mail]> <[e-mail]>

   [e-mail] (Gary Coffman) wrote:
 >[e-mail] (W8JI  Tom) writes:
>>[e-mail] (Gary Coffman) writes:

>>>A classic example is a shunt fed grounded base halfwave vertical.
>>>You have to shunt feed it because the "grounded" end is a very high
>>>impedance point, just as the top end is.

>>No, the grounded end is NOT a high impedance point. The highest
>>impedance point is the top.

Tom, you've made an error in this statement.  Both the top and bottom
are low impedance points.  The bottom is low impedance because it's
grounded, and the top repeats it.

>But wait, it's a halfwave, and you've been telling me that the
>impedance of a halfwave repeats at each end. So if you say it is high
>at the top, it has to be high at the bottom too. Can't have it both
>ways.

He made a mistake in this post, Gary.  The true operation of the tower
agrees with his previous descriptions of a halfwave conductor.  The
error should be obvious by virtue of the fact that a 1/4 wave vertical
exhibits a high impedance at the top.

     <self-congratulations deleted>  <g>

>Frankly, I believe that the bottom is also a high impedance

This is ridiculous.  The bottom is ground.  <sigh>

>from the only point of view that matters here, that of the currents
>on the conductor.

Point of view doesn't matter.  Current will be maximum at the bottom.

>Earth in and of itself has no particular impedance, high or low. It
>assumes whatever impedance is necessary to satisfy Z=E/I for the
>values of E and I measured across and along points in the mesh.

We're talking about earth ground, not the resistance of a handful of
dirt.  RF current on a single conductor will readily flow into earth,
never to return.

>The whole fallacy of your and Jack's argument has been this
>insistence on an absolute impedance for ground that is low.

When's the last time you received an RF burn from earth ground?

Gary, you have just made me very glad to be on this side of the
argument.  ;)

73,
Jack  WB3U


From [e-mail] Sun Apr 14 17:35:13 1996
From: [e-mail] (W8JI  Tom)
Newsgroups: rec.radio.amateur.antenna
Subject: Re: MFJ Artificial Ground
Date: 14 Apr 1996 10:10:30 -0400
Message-ID: <4kr10m$[e-mail]>
References: <4kq22m$[e-mail]>


Hi Jack,
In article <4kq1mh$[e-mail]>,
[e-mail] (WB3U) writes:

>My apologies Tom, you were correct.  If it's shunt fed in the center,
>it behaves like two 1/4 waves.  It will have a low impedance at the
>bottom and a high impedance at the top.  BTW, I also found some
>interesting information on J-fed 3/4 wave towers, but that's another
>story.
>
>The other thing I discovered is that the 1/2 wave shunt-fed vertical
>is in no way a "classic example" of anything other than a 1/2 wave
>shunt-fed vertical.  Can I suggest that we resolve the issues that are
>actually relevant to this thread before moving on to areas like this?
>
>73,
>Jack  WB3U

No need to worry or appologize Jack. You're always disagree in a
non-personal and mature way.

The grounded shunt fed 1/2 wave vertical may be a bit tricky to
understand, but it is also good for proving the point about feedline
lengths. If that antenna is modeled (using a program capable of analyzing
currents at close spacings) you'll see something interesting. When
shunt-fed at a point 1/4 wl above earth the tower has very little current
below the shunt feed wire tie-in point!

If I were going to build a system like that I'd use a skirt for a feed
wire.

Anyway, the very example given by someone to discredit well accepted fact
actually confirms the fact someone was attempting to disprove.

Use a 1/4 wl coaxial feeder to a dipole, and the line will have minimum
parallel line currents (as a general rule). Use a 1/2 wl feeder, and the
line length helps bring the problem right home to the hamshack.

73 Tom


From [e-mail] Sun Apr 14 17:35:14 1996
From: [e-mail] (Krogner)
Newsgroups: rec.radio.amateur.antenna
Subject: Monoband ant's for sale
Date: 12 Apr 1996 16:30:39 -0400
Message-ID: <4kmehf$[e-mail]>
Reply-To: [e-mail] (Krogner)

I have the following, all disassembled in excellent shape:
          two  Hygain 204 ba's  4-el 20 meter   $200. each
          one Cushcraft 15-4CD 4-el 15 meter   $150.
          one Cushcraft 10-4CD 4-el 10 meter   $135.

All antennas have coaxial baluns.  The 10 meter antenna is less than one
year old.  The other antennas have lots of new hardware--stainless.  Will
deliver to
Dayton in May.  No element in any package is longer than 6' 6".   Contact
Ken-WD9INF.  Email  Krogner at AOL.COM.


From [e-mail] Sun Apr 14 17:35:15 1996
From: [e-mail] (Cecil A. Moore~)
Newsgroups: rec.radio.amateur.antenna
Subject: Re: more problems
Date: 9 Apr 1996 20:42:22 GMT
Distribution: world
Message-ID: <4kei3e$[e-mail]>
References: <4ka3rq$[e-mail]>

In article <4ka3rq$[e-mail]>,  <[e-mail]> wrote:
>0 aslong as i leave the center pen in the hole and theshell not touchingit
>works fine to receive i don'tdare transmitt though.

Sounds to me like your coax braid is shorted to the coax center conductor.

73, Cecil, KG7BK, OOTC  (not speaking for my employer)


From [e-mail] Sun Apr 14 17:35:15 1996
From: [e-mail] (WB3U)
Newsgroups: rec.radio.amateur.antenna
Subject: Re: more problems
Date: Mon, 08 Apr 96 14:30:04 GMT
Message-ID: <4kbfdh$[e-mail]>
References: <4ka3rq$[e-mail]>

  [e-mail] wrote:

>well i have elimonated the transmission line and the antenna. now
>when I plug my connector on my hf rig the s reading goes from s7 on
>wwv s 10 mhz signal to 0 aslong as i leave the center pen in the hole
>and theshell not touchingit

I'm not sure I saw your original post.  Could you describe the entire
antenna system (working outward from the coax connector on the rig)?

73,
Jack


From [e-mail] Sun Apr 14 17:35:16 1996
From: [e-mail] (Walt Davidson)
Newsgroups: alt.radio.scanner,alt.radio.pirate,aus.radio,rec.radio.amateur.antenna,rec.radio.amateur.equipment,rec.radio.amateur.misc,rec.radio.scanner,rec.radio.shortwave,uk.radio.amateur
Subject: Re: Naughty Rude Words
Date: Wed, 10 Apr 1996 22:00:22 GMT
Message-ID: <4khb6p$[e-mail]>
References: <4jloui$[e-mail]> <[e-mail]> <4k4o5m$[e-mail]> <4kaktk$[e-mail]> <[e-mail]>

Michael J Wooding <[e-mail]> wrote:

>>his mother and I will need
>>to consider installing a parental lock!

>Sorry Walt, I just have to ask - WHERE?

On his mouth, preferably!

73 de G3NYY

--
Walt Davidson               E-mail: [e-mail]
                                    [e-mail]



From [e-mail] Sun Apr 14 17:35:17 1996
From: Michael J Wooding <[e-mail]>
Newsgroups: alt.radio.scanner,alt.radio.pirate,aus.radio,rec.radio.amateur.antenna,rec.radio.amateur.equipment,rec.radio.amateur.misc,rec.radio.scanner,rec.radio.shortwave,uk.radio.amateur
Subject: Re: Naughty Rude Words
Date: Tue, 9 Apr 1996 21:44:19 +0100
Distribution: world
Message-ID: <[e-mail]>
References: <4jloui$[e-mail]> <[e-mail]>

In article <4kaktk$[e-mail]>, Walt Davidson
<[e-mail]> writes
>his mother and I will need
>to consider installing a parental lock!

Sorry Walt, I just have to ask - WHERE?

Me

Michael J Wooding   [e-mail] - CompuServe: 100441,377
WWW: http://www.eolas.co.uk/ag/vhfcomm.htm (hambits.htm & hamclip.htm)
WWW: http://www.clearlight.com/~vhfcomm
Tel: [phone]   Fax: [phone]
KM Publications, 5 Ware Orchard, Barby, Nr.Rugby, CV23 8UF, UK
VHF Communications Magazine - Especially Covering VHF, UHF and Microwaves


From [e-mail] Sun Apr 14 17:35:19 1996
From: [e-mail] (Jim Flanders)
Newsgroups: rec.radio.amateur.antenna
Subject: Re: Need Guidlines for F.S. Tower Bases
Date: 9 Apr 1996 12:45:58 GMT
Message-ID: <4kdm66$[e-mail]>
References: <4jhcl7$[e-mail]>

Actually, once you learn one key trick, boring through that limestone
is not impossible.  I put a lot of fence posts in my rent houses.
The trick is to wet down the limestone when using a power hole digger.
The limestone then cuts like a bar of soap.
   In Plano, the city engineers have the required information on the
size of tower bases.  Also available is the information given out by
the manufacturers of the towers.  A letter to the manuf. will get you
more information than you will ever need.

Jim W0oog/5  @ Plano (147.180 +) & (14.243 1100 CT on sub vets net)
In article <4jhcl7$[e-mail]>, [e-mail] says...
>
>A friend of mine has a free standing tower and needs some info on
>how to make the base for it.  We have two problems here.
>
>1.  How big should the base be.  (i.e.  should the mass of the
>concrete equal or be more than the mass of the tower?  Are we
>trying to shift the center of gravity to below the soil?)
>
>2.  In central Texas the soil has alot of limestone in it.  It is
>very difficult to even dig a hole for a rose bush, let alone a
>tower base.  We have talked to some drilling companies, but prices
>are up in the thousands of dollars.  Explosives are out of the
>question.  Any advice on how to dig the hole?  Can a compromise be
>made by digging a shallower, but wider pit?
>
>Any advice is appreciated.  My friend is going to seek help from
>the County Engineer.  However at this point we no not what were
>doing.
>
>Thanks in advance
>73s de KI5XW
>



From [e-mail] Sun Apr 14 17:35:20 1996
From: Edward Lawrence <eal>
Newsgroups: rec.radio.amateur.antenna
Subject: Re: Need help with high SWR problem
Date: 8 Apr 1996 13:31:43 GMT
Message-ID: <4kb4fv$[e-mail]>
References: <4k3dj0$5mg@lambchop>

Ron Thompson <[e-mail]> wrote:
>I have a mobile 2M 50W radio I am using as a base rig.
>It runs off of a 20A power supply, and feeds a 75 foot
>piece of RG-213 connected to a Cushman Ringo Ranger II
>7db gain antenna.
>
snip

>I then moved the SWR meter to the antenna end of the
>feedline, and took another reading.  The SWR was
>over 8:1, and the indicated RF power was about 50 Watts.
>
snip
>Please e-mail reply as well as posting.
>
>KE6AGC
>Ron Thompson
>[e-mail]
>
OK Ron, perhaps this will help.  I snipped some stuff, but left the correct
location/SWR in, above.  You will need to readjust your antenna to correct the
SWR AT THE ANTENNA!  Measuring the SWR at the transmitter end can be prone to
large errors, as you have found out.
Get the instructions for the Ringo, and set all diamentions back to the factor
y
recomemdations for the frequency of interest.  Make minor 'tweeks from there i
f
the SWR is still high.  You should fix your problem in 20 minutes or so.
Ed Lawrence  WA5SWD



From [e-mail] Sun Apr 14 17:35:21 1996
From: [e-mail]
Newsgroups: rec.radio.amateur.antenna
Subject: New Web, URL change !!!
Date: Tue, 09 Apr 96 22:50:42 EDT
Message-ID: <[e-mail]>


Please my note of my URL change, you will still get there
will the old one, but make sure you make change within
the next month or two.

new url:
http://www.moonstar.com/~wa4pgm

ham radio and kayaking pages.
Lots of changes in the last week, check it out and please
add my URL to your list/page.

Thanks,
Kyle



From [e-mail] Sun Apr 14 17:35:22 1996
From: [e-mail] (Jim Flanders)
Newsgroups: rec.radio.amateur.antenna
Subject: Re: Question abt 2 meter mobile ant.
Date: 10 Apr 1996 12:43:52 GMT
Message-ID: <4kgae8$[e-mail]>
References: <497cc$103915.8b@NEWS>

Dan:
  Radio Shack also sells a 5/8 wave mag mount although the cost is a
little high.  MFJ (Mighty Fine Junk) has one also at a better price.
On the purchase of the HTX202.  Please allow me to recommend that you
also purchase a five year guarantee with it. ($30) I had mine two weeks
when I spilled coke down in the phone jacks.  The charge circuit
stopped working.  I got it back in ten days, and its been fine for
almost three years now.  When the lithium battery goes, it is covered
in the garantee, otherwise it'll cost >$30 to replace (unless you do
it yourself).

Jim W0oog/5

In article <497cc$103915.8b@NEWS>, [e-mail] says...
>
>I am planning to purchase a 2 meter portable (HTX-202) and maybe a
mobile ant.
> What is recommended, if it's even neccessary? 1/4, 1/2, 5/8? Is a
magnetic
>mount possible?
>Thanks.
>
>-Dan.
>



From [e-mail] Sun Apr 14 17:35:23 1996
From: Charles Bolland <[e-mail]>
Newsgroups: rec.radio.shortwave,rec.radio.amateur.antenna,rec.radio.amateur.digital.misc,rec.radio.amateur.equipment,rec.radio.amateur.misc,rec.radio.amateur.policy,rec.radio.amateur.space,rec.radio.noncomm,rec.radio.scanner,rec.radio.shortwave,rec.radio.swap
Subject: Radio Station Database Program Stand Alone
Date: Thu, 11 Apr 1996 01:00:53 -0400
Message-ID: <[e-mail]>

Sir,

It's still available.  The IBM/DOS Broadcasting Radio Station Database
Program for Longwave, Mediumwave, and Shortwave.  Over 4,000 records
included already.  The program is completely read and write.  Records
can be added or changed.  Sorts in many different formats both on your
screen and printing.

If you would like a copy of the program, send your request to
"[e-mail]".  Please include your MAILING ADDRESS. For example,
your street number, city, state and zipcode.  Also include your Email
address.

The program will be sent to you via Email probably within 24 hours if
not sooner.  If you request the program and haven't received it in that
period, check back with me..

Remember to send your address.  Requests without a mail address will no
longer be acknowledge to save time on the internet.  In the past,
requests without an address were reminded with a message.  Usually, the
reminder went unanswered anyway.  If it was, the reply was sometimes
very rude.

This program is free!  Everything works.  It has many features and they
all work, not like shareware where some of the features work and others
don't.

You address will be kept confidential.  I will be sending you a first
class letter later explaining another full featured Database program
available. It's very big!


From [e-mail] Sun Apr 14 17:35:24 1996
Newsgroups: rec.radio.amateur.antenna
From: [e-mail] (Marci & Dan Mouer)
Subject: Repeater freqs requested.
Message-ID: <497cc$11116.312@NEWS>
Date: Tue, 09 Apr 96 22:00:36 GMT

Could someone please tell me what the repeater freqs for Charels
County MD, Washington, DC and Springield/Fairfax, VA area are.
Thanks.

-Dan.



From [e-mail] Sun Apr 14 17:35:25 1996
From: AC6V <[e-mail]>
Newsgroups: rec.radio.amateur.antenna
Subject: Re: Repeater freqs requested.
Date: 10 Apr 1996 02:38:36 GMT
Message-ID: <4kf6vc$[e-mail]>
References: <497cc$11116.312@NEWS>
To: [e-mail]

Goto Lycos search engine. Search for ARTSCI and you will find an on-line
repeater guide by state.

Good Luck
73
Rod

--
*****************************************************************
Hark! I Have Hurled My Words To The Far Reaches Of The Earth!
What King Of Old Could Do Thus ?  --- AC6V
*****************************************************************
A Man May Know Of The World Without Leaving The Shelter Of His
Own Home!
Loa-Tsze
*****************************************************************




From [e-mail] Sun Apr 14 17:35:26 1996
From: The Colliver's <[e-mail]>
Newsgroups: rec.radio.amateur.antenna
Subject: Re: REQUEST SUGGESTION FOR HF ANT
Date: 11 Apr 1996 04:17:23 GMT
Message-ID: <4ki14j$[e-mail]>
References: <[e-mail]>
To: [e-mail]

I just purchased a "modular" Hustler HF mobile antenna (mag mount, mast,
and 20-m resonator).  I love it for stationary mobiling.  Have worked 12
states and 4 countries in about 5 hours of operating it on 20-m.

Good luck,
73 KB8UXV



From [e-mail] Sun Apr 14 17:35:27 1996
From: Nick Reddish <[e-mail]>
Newsgroups: rec.radio.amateur.antenna
Subject: Rotator - Sky King SU-2000-SE
Date: Thu, 11 Apr 1996 11:05:42 -0700
Message-ID: <[e-mail]>

I'm looking for any information on the Sky King SU-2000-SE rotator. If
anyone can tell me what the connects to what on this box It would be very
much appreciated.

Regards & 73's


From [e-mail] Sun Apr 14 17:35:27 1996
From: Michael.Kaaber%12:210/203.0 (Michael Kaaber%12:210/203.0)
Date: 11 Apr 96 15:34:35
Newsgroups: rec.radio.amateur.antenna
Subject: Seeking parabol for 23cm
Message-ID: <[e-mail]>

Hi All!

I am looking for a 23cm parabol to use with Packet forward links.

Do you now about someone who can help me ?

Regards,
 Michael Kaaber
 # Origin: The Radio Amateur BBS .. [203.19k2] [204.28k8] [2003.ISDN]
(12:210/203)
--
|Fidonet:  Michael Kaaber%12:210/203.0 2:301/249.666
|Internet: Michael.Kaaber%12:210/203.0
|
| Standard disclaimer: The views of this user are strictly his own.



From [e-mail] Sun Apr 14 17:35:29 1996
From: [e-mail] (Cecil A. Moore~)
Newsgroups: rec.radio.amateur.antenna
Subject: Re: SW receiver antenna question...
Date: 9 Apr 1996 16:16:43 GMT
Distribution: world
Message-ID: <4ke2hb$[e-mail]>
References: <[e-mail]>

In article <[e-mail]>,
ED WELCH <[e-mail]> wrote:

>For SWL should an outside long-wire antenna be pointed towards the
>direction of the broadcast or should it be positioned "broadside" to the
>desired direction?
>I'm curious to the direction answer and also the "why" of it.

Hi Ed, wire antennas have directional lobes depending on
their wavelength. A single wire antenna can be looked
upon as half a dipole. Broadside directivity drops off
when a dipole is much above 10/8 wavelength and the
response breaks into a cloverleaf pattern. At higher
frequencies, it becomes multilobed. If you know the
frequency and direction of the station, a 10/8 dipole
is a very good antenna. For a range of frequencies,
I would recommend a dipole that is 10/8 wavelength
at the highest frequency of interest. You can turn
such an antenna broadside to the desired locations.

I use a 102 ft center-fed, ladder-line-fed dipole for
SW listening. An antenna tuner helps to peak the
received signals by resonating the entire system.

73, Cecil, KG7BK, OOTC  (not speaking for my employer)


From [e-mail] Sun Apr 14 17:35:30 1996
From: [e-mail] (Mike McCarty)
Newsgroups: rec.radio.amateur.equipment,rec.radio.amateur.antenna
Subject: Re: The Transmitter Chassis (Was MFJ Artificial Ground)
Date: 13 Apr 1996 01:52:27 GMT
Message-ID: <4kn1cs$[e-mail]>
References: <4k43ol$[e-mail]> <[e-mail]> <4kbeqv$[e-mail]> <4kccpb$[e-mail]>

In article <4kccpb$[e-mail]>,
WB3U <[e-mail]> wrote:
)The discussion regarding artificial grounds and coax shield currents
)has raised a related issue that I think is widely misunderstood.
)
)First, it was stated in the other discussion that feedline currents
)radiate because they are unable to enter the transmitter and return to
)their source.  I have disputed this because there are many openings
)and pathways into the typical transmitter for current flowing on the
)outer chassis.  If the current is attracted to the inner chassis, and
)it appears that it is, it can find a way in.  The evidence of this is
)that RF in the shack often causes the internal workings of the
)transmitter to malfunction.  In addition, removing the cabinet of the
)transmitter will typically have little or no effect, good or bad, on
)the RF in the shack.

ALL alternating current radiates. With coax, you have (nearly) equal
currents flowing in opposite directions, with one enclosed in the other.
Each of the currents then radiates an electromagnetic wave of (nearly)
equal amplitude but (nearly) opposite phase. These interfere
destructively, resulting in (nearly) zero radiation from the feedline.

[rest gone]

Mike
--
----
char *p="char *p=%c%s%c;main(){printf(p,34,p,34);}";main(){printf(p,34,p,34);}

I don't speak for DSC.         <- They make me say that.


From [e-mail] Sun Apr 14 17:35:31 1996
From: [e-mail] (WB3U)
Newsgroups: rec.radio.amateur.equipment,rec.radio.amateur.antenna
Subject: Re: The Transmitter Chassis (Was MFJ Artificial Ground)
Date: Sun, 14 Apr 96 01:29:55 GMT
Message-ID: <4kps09$[e-mail]>
References: <4kn1cs$[e-mail]> <4knght$[e-mail]>

   [e-mail] (W8JI  Tom) wrote:

>Please read what Mike wrote. That's exactly how ANY shield works.
>
>Even the cabinet of the rig works that way.

Except most cabinets have big holes and lots of wires going
in and out.  ;)

73,
Jack  WB3U


From [e-mail] Sun Apr 14 17:35:32 1996
From: [e-mail]
Newsgroups: rec.radio.amateur.antenna
Subject: Towers, How High?
Date: Thu, 11 Apr 96 19:10:09 PDT
Message-ID: <[e-mail]>


If you follow Rohn's advice about guy placement, how high can
a 25G or 45G be if it only has to support the end of a dipole?
I'm talking about something pretty fragile which may or may
not survive 70 or 80 mph winds.  What's the highest anyone has
heard of?



From [e-mail] Sun Apr 14 17:35:32 1996
From: Jim <[e-mail]>
Newsgroups: rec.radio.amateur.antenna
Subject: Re: Towers, How High?
Date: 12 Apr 1996 13:26:47 GMT
Message-ID: <4kllmn$[e-mail]>
References: <[e-mail]>

That may depend on the dipole.

I once planned a 75 meter cage dipole (8-strand, 3-foot element diameter)
in a semi-V configuration with the ends on freestanding '25 and the center
on guyed '45 at 50 feet.  The shape of the yard dictated that 20 feet
was about as high as I could put the end towers, which is as high as
I wanted to climb an unsupported '25 anyway -- and probably as much
load as the '25 would take.

You should take into consideration the height of your dipole above
ground, without as much consideration as "how high can I get."
You'll do better with the right height than with the most height.
Guyed Rohn 25 or 45 will safely go higher than you can climb.

Oh, I never built the 75m cage, and I'm still just one state short
of 75 phone WAS -- Hawaii -- the cage would have been broadside to
KH-land.

Jim N6OTQ




From [e-mail] Sun Apr 14 17:35:34 1996
From: Cecil Moore <[e-mail]>
Newsgroups: rec.radio.amateur.antenna
Subject: Re: tuner/balun
Date: 9 Apr 1996 16:03:22 GMT
Message-ID: <4ke1oa$[e-mail]>
References: <4ka8lt$[e-mail]> <4kcmpk$[e-mail]>

[e-mail] (W8JI  Tom) wrote:
>Did you always use the maximum "C" that permitted a match (it should be
>close to fully meshed in both cases)?

The two settings were very close to each other. "C" was toward the
maximum at about 2 o'clock.

>What tuner did you test, and what balun?

MFJ949, 13 #77 beads on RG213 for a choke, and the Amidon HBHT200 4:1 voltage
balun. Would a multi-turn toroidal choke be more efficient?

>Was the load a pair of 150 ohm resistors with the center tap grounded, or
>a totally floating load?

It was eight 600 ohm resistors with the center tap grounded.

>What instrument measured the power?

100 MHz oscope measured the voltages. Ladder-Lizard pickup loop
measured the relative currents.

73, Cecil, KG7BK, OOTC  (not speaking for my employer)





From [e-mail] Sun Apr 14 17:35:35 1996
From: [e-mail] (W8JI  Tom)
Newsgroups: rec.radio.amateur.antenna
Subject: Re: tuner/balun
Date: 9 Apr 1996 21:40:47 -0400
Message-ID: <4kf3iv$[e-mail]>
References: <4ke7ps$[e-mail]>

In article <4ke7ps$[e-mail]>, Cecil Moore
<[e-mail]> writes:

>
>One possible explaination might be if I have some
>common mode currents. Common mode currents tend to cancel in
>the 4:1 voltage balun. I assume they tend to heat up beads.
>If the common mode currents see a high impedance with the 4:1
>voltage balun and a low impedance with the beads, that could
>explain my readings and also score a point for the voltage
>balun. :-)  I didn't try to measure common currents.
>
>73, Cecil, KG7BK, OOTC  (not speaking for my employer)
>
>
Hi Cecil

I suspect the bead balun had the common mode problem Cecil. They really
stink with high Z loads. Some of the differential power could be appearing
as common mode, and not even showing up on the measuring system you are
using.

Bead baluns are only good for low common mode impedance loads, unless you
have several feet of beads. Remember the impedance increases at a linear
rate until reaching  a resonance limit, then it drops again. And the
impedance is about equal parallel resistance and reactance on 75 meters.

I use a tall stack of lower perm ferrites with multi-turns, or an air
wound choke.

a---------))))))--------------c--150---gnd

b---------))))))--------------d--150---gnd

Assuming b is grounded,  common mode is caused by d not having enough
voltage and current. Part of the current from a to c returns through gnd
to the tuner. The common mode choke impedance of the balun has to be
several times 150 ohms, or stuff will be a little unbalanced. Might not be
losses, just unbalance causing the shortfall.

73 Tom


From [e-mail] Sun Apr 14 17:35:36 1996
From: [e-mail] (Wayne White)
Newsgroups: rec.radio.amateur.antenna
Subject: Re: Wanted Info.:: Mookraker Antenna's
Date: 12 Apr 1996 21:59:26 GMT
Message-ID: <4kmjnu$[e-mail]>
References: <[e-mail]>

Copper Electronics carries them. They are on the WWW.

In article <[e-mail]>,
[e-mail] says:
>
>Does anybody no were I can get the big moonraker CB antenna's
>
>any help would be appreciated
>
>
>thank's
>-Rick
>
>--
>C.M.S
>Computers:(Apple, IBM, NEC, DEC, ) Network Products, Hard
Drives:(Segate, Connner, Quantum,) Software, Semiconductor, Passive
Components, Connectors.....a
>Phone: [phone] M-F 8-6 pm EST
>Fax:   [phone]
>Email: [e-mail]
>Web Page: http://www.xtalwind.net/~alpha1/index.html
>
>*** We buy used and outdated Computer Equipment / Fax us you list ***
>=====================================================================


From [e-mail] Sun Apr 14 17:35:37 1996
From: [e-mail] (Cecil A. Moore~)
Newsgroups: rec.radio.amateur.antenna
Subject: Re: What is a current node
Date: 14 Apr 1996 00:15:42 GMT
Distribution: world
Message-ID: <4kpg3e$[e-mail]>
References: <4kjsmr$[e-mail]>

In article <4kjsmr$[e-mail]>,
CHARLES J. MICHAELS <[e-mail]> wrote:
>
>       Becareful of defining a current loop as the point on an antenna
>or transmission line of maximimum current.  The current loop may not even
>be on the line or antenna.

Hi Charlie, It's heck trying to keep everybody honest, isn't
it? When we talk about a current loop in the transmission
line, I think we are talking about the transmission line
current maximum even if the current elsewhere may be greater.
Depending on frequency, there may be many current loops and
nodes up and down a transmission line even if "The" current
loop (meaning The largest current loop?) is not on the
transmission line.

73, Cecil, KG7BK, OOTC  (not speaking for my employer)


From [e-mail] Sun Apr 14 17:35:38 1996
From: [e-mail] (CHARLES J. MICHAELS)
Newsgroups: rec.radio.amateur.antenna
Subject: Re: What's a G5RV
Date: 12 Apr 1996 06:29:14 GMT
Message-ID: <4kkt7q$[e-mail]>


Cecil wrote -


Hi Charlie, you're right in that any 102 ft dipole will radiate
the same percentage of power reaching it. It's the total power
that we are discussing. If there's neglible loss in the feed
system, the antenna will radiate more power than if there's
not neglible loss in the feed system. I haven't changed my
antenna but I am radiating at least double the RF power on 75m
after I gave the 4:1 a load of 300 ohms resistive instead of
the 1000+j2000 ohm load that I was previously giving it.

Cecil,
        Precisely my point.  We are really discussing a feed
system.

charlie,  W7XC
--


From [e-mail] Sun Apr 14 17:35:39 1996
From: [e-mail] (Don Phelps)
Newsgroups: rec.radio.amateur.antenna
Subject: Re: Which is better on 80
Date: Fri, 12 Apr 1996 16:55:00 GMT
Message-ID: <[e-mail]>
Distribution: world
References: <4kjg9c$[e-mail]> <4k3sdl$[e-mail]> <4k5


My best antenna on 80 was full length 135 ft dipole feed with
450 ohm ladder line from a Johnson Matchbox.
I used multiple conductors spaced 10 feet apart to widen
the bandwidth and lower impedance swings.

To lower losses in the ground reflection, I oriented the antenna
vertically, hanging down from a tall limbless tree trunck
 which leaned over, all being on top of a knoll.

The antenna also operated very well on 40 as a colinear dipole.
 >
 >I tried both a 130 foot long dipole and a G5RV length dipole (105 feet) at
 the
 >same location, about 50 feet high between two trees.  I fed both of them
 >with 450 ohm ladder line to a Johnson Matchbox Jr.
 RL> The pattern of a dipole changes very little as it's shortened from a
 RL> half  wavelength clear down to infinitesimally short. If the loss can
 RL> be kept  small, the gain will therefore also change very little.

Keeping ground losses small is the challenge.

Don
N6MCE


... [e-mail]; Fido 1:125/104; DharmaNet 96:101/104
___ Blue Wave/386 v2.30 [NR]


From [e-mail] Sun Apr 14 17:35:40 1996
From: [e-mail] (Jim Garver)
Newsgroups: rec.radio.amateur.antenna
Subject: Re: Which is better on 80: 80 m dipole or G5RV (see text) ?
Date: 8 Apr 1996 23:21:41 GMT
Message-ID: <4kc725$[e-mail]>
References: <4k3sdl$[e-mail]> <4k52m8$[e-mail]>


I tried both a 130 foot long dipole and a G5RV length dipole (105 feet) at the
same location, about 50 feet high between two trees.  I fed both of them
with 450 ohm ladder line to a Johnson Matchbox Jr.
I found absolutely no performance difference between the two lengths on
80 and 75 meters, they both were excellent cloud warmers.  The 105 foot long
dipole was much easier to match on some of the higher bands and that is why
I cut it shorter.  The full size dipole presents a very high impedance on
even multiple frequencies like 40 meters.  The Matchbox doesn't like
impedances higher than about 2000 ohms.

Concerning the G5RV antenna, this is a length, not a design, IMHO.  Read the
article by Mr. G5RV himself in the First ARRL Antenna Compendium to find
out all about it.  The inbred coax-ladder line version is not as
easy to match nor is it as efficient as the all-ladder line G5RV antenna.

WA7LDV

--
[e-mail]                             I don't speak for Intel


From [e-mail] Sun Apr 14 17:35:41 1996
From: [e-mail] (Roy Lewallen)
Newsgroups: rec.radio.amateur.antenna
Subject: Re: Which is better on 80: 80 m dipole or G5RV (see text) ?
Date: Thu, 11 Apr 96 17:43:05 GMT
Message-ID: <4kjg9c$[e-mail]>
References: <4k3sdl$[e-mail]> <4k52m8$[e-mail]> <4kc725$[e-mail]>

In article <4kc725$[e-mail]>,
   [e-mail] (Jim Garver) wrote:
>
>I tried both a 130 foot long dipole and a G5RV length dipole (105 feet) at
the
>same location, about 50 feet high between two trees.  I fed both of them
>with 450 ohm ladder line to a Johnson Matchbox Jr.
>I found absolutely no performance difference between the two lengths on
>80 and 75 meters, they both were excellent cloud warmers. . .

The pattern of a dipole changes very little as it's shortened from a half
wavelength clear down to infinitesimally short. If the loss can be kept
small, the gain will therefore also change very little. (The gain
difference between a half wavelength dipole and an infinitesimally short
one, if loss could be kept to zero, is less than 0.5 dB.) So the result you
saw should be expected.

Roy Lewallen, W7EL


From [e-mail] Sun Apr 14 17:35:42 1996
From: [e-mail] (Jim Flanders)
Newsgroups: rec.radio.amateur.antenna
Subject: Re: Which is better on 80: 80 m dipole or G5RV (see text) ?
Date: 9 Apr 1996 13:12:49 GMT
Message-ID: <4kdnoh$[e-mail]>
References: <4k3sdl$[e-mail]>

One problem I have seen hapen with a G5rv.  They installer put it up
with the feedline at the tower and ran it like an inverted V.  The
installation totally failed.  It seems that since the upper part of the
feedline is a radiator, and the tower was grounded, it destroyed the
usefulness of the antenna.  Most G5RV installations need it to be
put up as a flat top and the feed line drop vertically for the first
32 feet or so.  If you can't do this, than I would prefer the 80 meter
dipole.  Have you thought of a shortened dipole?

-----(coil)-----| |-----(coil)-----
               (balun)
                | |
                | |<- coax feedline (any length)
|<------------- 90 feet -----------|  See arrl antenna handbook

This antenna can be broadbanded by fanning two wires of slightly
different lengths at the outerside of the coils.  A separation of
three feet at the ends is adequate.

Jim W0oog/5


In article <4k3sdl$[e-mail]>, [e-mail]
says...
>
>Need advice/opinions:
>
>I am putting up a 48' tower very soon and
>have run into difficulty. I have just done some
>measuring and discovered that if I decide to
>go with an 80m dipole, the ends will have to
>be bent and run along my wooden fence for 9 feet
>and 5 feet for each of the two ends respectively.
>
>The alternative is to put up a G5RV or some
>other loaded, shorter antenna. These antennas
>will fit comfortably in my lot, without bending
>the ends.
>
>This antenna is exclusively for use on 80m, and
>my current belief is that the dipole will be a
>better performing antenna, even with the ends folded
>slightly, as described above.
>
>Can anyone share any experiences with similar setups ?
>
>Please post to this newsgroup, since our email system
>is frequently down.
>
>Thanks for any help.
>Mat
>
>



From [e-mail] Sun Apr 14 17:35:44 1996
From: Chuck Vaughn <[e-mail]>
Newsgroups: rec.radio.amateur.antenna
Subject: Re: Yagi v/s Log
Date: Fri, 12 Apr 1996 11:38:22 -0800
Message-ID: <[e-mail]>
References: <4klqsa$[e-mail]>

Rodrigo E. Rodriguez R. - CE6NUG wrote:
> =

> =B4lo world.
> Could someone talk about major difference(s) between yagi and log periodi=
c
> antennas...??
> Of course I DO know that log-per have biggest bandwidth... but I
> guess that is not the only one.
>
That really is the major difference. Although logs can have a
lot of elements to increase the gain.

I have a KLM 7 element Log Periodic and find that it is equivalent
to a 3 element monoband yagi everywhere from 13 to 30 MHz except
with lower F/B ratio, only about 12 to 15 dB. The gain and F/B
of a log can be increased on portions of its frequency coverage
by adding parastic elements at the proper places for the band
of interest.

Why don't more amateurs use them? There seems to be a stigma =

attached to logs that is simply not true. My log has been up
for 11 years and has been very competitive with other antennas
in it's size range. I highly recommend it as an antenna.

73,

Chuck Vaughn - AA6G    <[e-mail]>


From [e-mail] Sun Apr 14 17:35:45 1996
From: [e-mail] (Rodrigo E. Rodriguez R. - CE6NUG)
Newsgroups: rec.radio.amateur.antenna
Subject: Yagi v/s Log
Date: 12 Apr 1996 14:55:06 GMT
Message-ID: <4klqsa$[e-mail]>

┤lo world.
Could someone talk about major difference(s) between yagi and log periodic
antennas...??
Of course I DO know that log-per have biggest bandwidth... but I
guess that is not the only one.
Thanks in advance for your help.
73 & DX from Chile

Rod.

--

 Rodrigo E. Rodriguez R. : E-mail:  [e-mail]
 CE 6 NUG                :          [e-mail]
 Network Consultant      :          [e-mail]
 Electronic Eng. ST      :
 Federico Santa Maria    : AMPRnet: [e-mail]
 Tech. University        : Phone  : [phone] // (32) 69-3542
=========================================================================
 Address:  1 Poniente # 965      Depto. 14      Vina del Mar - CHILE
=========================================================================
+--HI, I'm a signature virus  :-)  Copy me into your sign to join in. ---+


From [e-mail] Sun Apr 14 17:35:46 1996
From: [e-mail] (Tom Bruhns)
Newsgroups: rec.radio.amateur.antenna
Subject: Re: Zepp, Double Extended - Why?
Date: 12 Apr 1996 17:11:15 GMT
Message-ID: <4km2rj$[e-mail]>
References: <[e-mail]>

[e-mail] wrote:

: The books say that when the length of a dipole is increased
: beyond a half wave, the doughnut radiation pattern grows a lot
: of side lobes.  What good is that?  Why has the standard
: advice always been to cut it longer than 1/2 WL?

From the subject line, I gather you are referring to the
"extended double Zepp" antenna, which is, from my memory,
generally taken to be about 1-1/4 waves long, or 5/8 wave
on each side.  As such, at least in freespace, it will
have the same pattern as a 5/8 wave over an infinite
ground plane (and its mirror image).  I believe it is only
when you make the antenna longer that this that the
multiple side lobes start to develop.  In other words, I
believe the 1.25 wave "extended double Zepp" is to a
5/8 wave fed against a plane as a half-wave dipole is
to a 1/4 wave fed against a plane.


--
Cheers,
Tom
[e-mail]


From [e-mail] Sun Apr 14 17:35:47 1996
From: [e-mail]
Newsgroups: rec.radio.amateur.antenna
Subject: Re: Zepp, Double Extended - Why?
Date: Fri, 12 Apr 96 19:32:08 PDT
Message-ID: <[e-mail]>
References: <[e-mail]>  <4kl7f8$[e-mail]>


In Article<4kl7f8$[e-mail]>, <[e-mail]> w
rite:
> Path: beta.nova.org!uunet!in2.uu.net!newsfeed.internetmci.com!nuclear.micros
erve.net!pinetree
> From: [e-mail] (WB3U)
> Newsgroups: rec.radio.amateur.antenna
> Subject: Re: Zepp, Double Extended - Why?
> Date: Fri, 12 Apr 96 07:15:11 GMT
> Organization: Microserve Information Systems (800)-380-INET
> Lines: 17
> Message-ID: <4kl7f8$[e-mail]>
> References: <[e-mail]>
> NNTP-Posting-Host: pinetree.microserve.com
> X-Newsreader: News Xpress Version 1.0 Beta #4
>
>    [e-mail] wrote:
>
> >The books say that when the length of a dipole is increased
> >beyond a half wave, the doughnut radiation pattern grows a lot
> >of side lobes.  What good is that?  Why has the standard
> >advice always been to cut it longer than 1/2 WL?
>
> The splitting off of the figure-eight pattern into
additional
> lobes is accompnaied by gain.  However, the gain isn't
appreciable
> until the antenna is many wavelengths long.
>
> Where is this "standard advice" you're referring to?  I've
seldom seen
> recommendations that a single-band dipole be anything other
than 1/2
> wavelength.
>
> 73,
> Jack  WB3U

Can't give you examples, but all my life I've been hearing how
good they are.  Every time I've strung up a dipole, I've cut
it too long, even as I wondered why I was doing it.  It seems
to me that unless you know exactly what you want to do with
those sharp little lobes, you'd get more satisfaction out of a
broad radiation pattern.



From [e-mail] Sun Apr 14 17:35:47 1996
From: [e-mail] (CHARLES J. MICHAELS)
Newsgroups: rec.radio.amateur.antenna
Subject: Re: Zepp, Double Extended - Why?
Date: 13 Apr 1996 05:35:25 GMT
Message-ID: <4kneet$[e-mail]>


        The only reason to cut an antenna to a rather exact resonant
half wave length is to get a pure resistive feedpoint impedance.
        A virtue of the so-called EDZ is that it maintains essentially
a doughnut pattern over abvout a 2 to 1 frequency range and at the highter
frequency exhibits some gain over a half wave even if some powr does go
into the developiong side lobes because the main lobes bvecome slightly
thinner .

        Of course, off resonance the feed system mst handle the reactive
load .

charlie, W7XC
--


From [e-mail] Sun Apr 14 17:35:48 1996
From: [e-mail] (t▓s)
Newsgroups: rec.radio.amateur.antenna
Subject: ºTower Wanted - Californiaº
Date: Thu, 11 Apr 1996 12:54:54 GMT
Message-ID: <4kljvn$[e-mail]>

I am looking for a 451X Tower- (I think that's the right p/n)
It is a 40' crankup tower that when nested is only 10' high

Does anyone have one they want to unload?

Please forward any info to

t▓s
[e-mail]


********WARNING********
Unsolicited *commercial* email is subject to download/archival fee of
$525.00 US per message.
Viewing this message and/or E-mailing to the forementioned address denotes
acceptance of these terms.



From [e-mail] Thu Apr 18 00:46:37 1996
From: [e-mail] (Cecil A. Moore~)
Newsgroups: rec.radio.amateur.antenna
Subject: Re: "VISALIA MOBILE ANTENNA SHOOTOUT"
Date: 15 Apr 1996 20:55:12 GMT
Distribution: world
Message-ID: <4kud3g$[e-mail]>
References: <4ko5eo$[e-mail]>

In article <4ko5eo$[e-mail]>, Jesse Touhey  <[e-mail]> wrote:

>The location will at the U.S.Towers factory, Visalia Calif. So, If you

Anybody have directions and/or an address for U.S.Towers? thanks...

73, Cecil, KG7BK, OOTC  (not speaking for my employer)


From [e-mail] Thu Apr 18 00:46:39 1996
From: [e-mail] (SHWoldringh)
Newsgroups: rec.radio.amateur.antenna
Subject: Re: **  Need source of fiberglass tubing and poles **
Date: Sat, 13 Apr 1996 18:53:06 GMT
Message-ID: <[e-mail]>
References: <4kbqtl$[e-mail]>

On 8 Apr 1996 19:54:29 GMT, [e-mail] (Jim Flanders) wrote:


>However, I wish to make quite of few of these so it would be more
>professional looking (and lighter) if fiberglass.
>
>If anyone knows a source of fiberglass tubing and poles, please e-mail
>me, phone me @ 214-612-1103,  and in Dallas I'm on the Plano repeater.

Jim,

I once bought fiberglass tubing for a quad from Cubex Quad Antenna Co.
phone [phone].
They may have what you are looking for.
73

Coen
PA0COE


From [e-mail] Thu Apr 18 00:46:39 1996
From: [e-mail] (Burch Akin)
Newsgroups: rec.radio.amateur.antenna
Subject: Re: 10 m Antenna
Date: Mon, 15 Apr 1996 19:20:07 GMT
Message-ID: <4ku7ht$[e-mail]>
References: <4kmtpj$[e-mail]>

Greg Limeberry <[e-mail]> wrote:

>Could someone give me an opinion and why on the best available
>(premanufactured) 10 meter antenna? Also, could you comment on the
>vertical antenna?

I don't know if it is the best or not, but I use a Cushcraft AR-10
vertical antenna for 10 meters and I love it!  I bought it brand new
for $60 and worked 30+ states and most of the South American countries
in 2 small band openings (in the bottom of the sun spot cycle.)  I'm
sure it's not is good as a beam, but for the money you can't beat it.
I have also heard good things about the Amtron 99 antenna.

KE4ZQV



From [e-mail] Thu Apr 18 00:46:40 1996
Newsgroups: rec.radio.amateur.antenna
From: [e-mail] (Gary Wilcox)
Subject: 4BTV Vertical
Message-ID: <3172b5a0.0@nt_test.cacky.com>
Reply-To: [e-mail] (Gary Wilcox)
Date: Mon, 15 Apr 1996 20:46:24 GMT


All


        Does anyone have the documentation on the 4BTV vertical
antenna. I would be happy to buy a manual or pay for a photocopy.


73's Gary Wilcox
[e-mail]


From [e-mail] Thu Apr 18 00:46:41 1996
From: [e-mail] (CHARLES J. MICHAELS)
Newsgroups: rec.radio.amateur.antenna
Subject: Re: Antenna Farm
Date: 13 Apr 1996 05:05:18 GMT
Message-ID: <4kncme$[e-mail]>


Will and Ken,
        Beware the map of US showing earth conductivies.  It is
derived by the FCC from *proofs* of US AM BC station
antenna patterns and is therefore not necessarily indicative of earth
characteristics at HF.
        The material in that section of the ARRL Antenna Book
on earth effects is essentially that of my July 1987 QST article and
the map was added over my objections.
        See the curves of *skin depth* vs frequency.  Remember
howeve that the skin depth is that at which the current density is
.37 times that at the surface and actually goes somewhat deeper
but about 92 percent of the power loss is incurred in the first
*skin depth*.

Charlie,  W7XC
--


From [e-mail] Thu Apr 18 00:46:42 1996
From: [e-mail] (Roy Lewallen)
Newsgroups: rec.radio.amateur.antenna
Subject: Re: Antenna Modeling Software
Date: Tue, 16 Apr 96 06:44:10 GMT
Message-ID: <4kvfhr$[e-mail]>
References: <4kopk7$[e-mail]> <4kprm9$[e-mail]> <4ktf7o$[e-mail]>

In article <4ktf7o$[e-mail]>,
   [e-mail] (Robert G. Strickland) wrote:

>This is true. However, after much struggle and online time, I have
>determined that one cannot print the plots under W95. You/I have to
>run the program from the C:\ prompt; that is, quit W95 and restart the
>computer in DOS mode. Then, printing works okay. BTW, this is also
>true of Miniprop, another DOS program. I am not well versed enough to
>explain the reasons behind this, but it seems to be the case. Roy, you
>might want to look into this. Otherwise, I agree with others: EZNEC is
>a fine program that is entertaining, helpful, instructive and easy to
>use.

I would appreciate very much hearing from anyone who has been unsuccessful
-- or successful -- in printing EZNEC plots under Windows 95. I certainly
will look into this. Please send the info to me at [e-mail].

Thanks!

Roy Lewallen, W7EL


From [e-mail] Thu Apr 18 00:46:43 1996
From: [e-mail] (Robert G. Strickland)
Newsgroups: rec.radio.amateur.antenna
Subject: Re: Antenna Modeling Software
Date: Mon, 15 Apr 1996 08:17:22 -0400 (EDT)
Message-ID: <4ktf7o$[e-mail]>
References: <4kopk7$[e-mail]> <4kprm9$[e-mail]>

[e-mail] (Roy Lewallen) wrote:

>In article <4kopk7$[e-mail]>,
>   [e-mail] (CHARLES J. MICHAELS) wrote:

>>Ron,
>>      My EZNEC is windows not DOS .  But perhaps you mean something else.
>>Charlie, W7XC

>No, EZNEC is a DOS program. It can be run as a DOS application under
>Windows or Windows 95.

>Roy Lewallen, W7EL

This is true. However, after much struggle and online time, I have
determined that one cannot print the plots under W95. You/I have to
run the program from the C:\ prompt; that is, quit W95 and restart the
computer in DOS mode. Then, printing works okay. BTW, this is also
true of Miniprop, another DOS program. I am not well versed enough to
explain the reasons behind this, but it seems to be the case. Roy, you
might want to look into this. Otherwise, I agree with others: EZNEC is
a fine program that is entertaining, helpful, instructive and easy to
use.

Robert


Robert G. Strickland KE2WY
[e-mail]
Syracuse, New York



From [e-mail] Thu Apr 18 00:46:44 1996
From: "C. J. Hawley" <[e-mail]>
Newsgroups: rec.radio.amateur.antenna
Subject: Re: Antenna Modeling Software
Date: Mon, 15 Apr 1996 11:26:16 -0500
Message-ID: <[e-mail]>
References: <4kopk7$[e-mail]> <4kprm9$[e-mail]> <4ktf7o$[e-mail]>

Robert G. Strickland wrote:
>
> [e-mail] (Roy Lewallen) wrote:
>
> >In article <4kopk7$[e-mail]>,
> >   [e-mail] (CHARLES J. MICHAELS) wrote:
>
> >>Ron,
> >>      My EZNEC is windows not DOS .  But perhaps you mean something else.
> >>Charlie, W7XC
>
> >No, EZNEC is a DOS program. It can be run as a DOS application under
> >Windows or Windows 95.
>
> >Roy Lewallen, W7EL
>
> This is true. However, after much struggle and online time, I have
> determined that one cannot print the plots under W95. You/I have to
> run the program from the C:\ prompt; that is, quit W95 and restart the
> computer in DOS mode. Then, printing works okay. BTW, this is also
> true of Miniprop, another DOS program. I am not well versed enough to
> explain the reasons behind this, but it seems to be the case. Roy, you
> might want to look into this. Otherwise, I agree with others: EZNEC is
> a fine program that is entertaining, helpful, instructive and easy to
> use.
>
> Robert

I can't even run ezcalc from win95. I have to reboot to dos. I also like the
program anyway. Someone said something about the easy to use text files with
Beezley's AO, Wires, etc. I don't know what's easy about that. You have to dot

every i. I like the user interface with Elnec and Eznec where there are
considerable labor saving devices available when describing the antenna
coordinants, things like group edit, rotate and move elements, etc. I'm also a

little miffed that I bought AO and Wires back when they were $100 each and whe
n
Beezley upgraded the programs he told me that my upgrade price was printed in
QST......the same as everybody else. I also had the feeling when I was talking
 to
him about the key I erased when I was installing win95, that he suspected that
 I
was trying to steal something. I couldn't get the supposed backup key to work
for
some stupid reason on my part and he did help me though. I only use Eznec now.
 I
got it at the upgrade price by the way.

Chuck, KE9UW



From [e-mail] Thu Apr 18 00:46:46 1996
From: [e-mail]
Newsgroups: rec.radio.amateur.antenna
Subject: Re: Attic Wire antenna
Date: Mon, 15 Apr 1996 21:17:02 -0700
Message-ID: <[e-mail]>
References: <[e-mail]>

In article <[e-mail]>, Philip Bernacke
<[e-mail]> wrote:

> I have a crawl space for an attic and would like info on wire antennas
> less than 40 feet long for all but 80 and 160 meters.  Multi-band would
> be preferred.  Also design info on 2m and 70cm wire antennas would be
> welcome.  My homeowners association won't allow outside antennas so I'm
> stuck.  Any help would be appreciated and all responses will be answered.
> 73 de KA7TTI / Phil

When building our house I strung a 140' wire around the rafters.  It
happened to be 50'x20' but I'm sure you could put in a few excursions to
make up the 40m resonant length.  I fed it on one of the short sides with
450ohm ladder line to the shack and then fed it to a 4:1 current balun.  A
tuner was needed on some bands cuz of the close proximity of other house
wiring.  It worked quite well during the sunspot maximum--dx everywhere on
CW at 100w.  It also worked on SWL very well.  I thought of it as a
perfect antenna for those of us with restrictive CCand Rs.  Since then I
put up a 80m delta loop with the apex high in a fir tree.  The base is
only 5' above the ground strund along a wooden fence.  It is also fed with
a 4:1 balun in a lower corner and coax to the shack.

Good luck, Gary


From [e-mail] Thu Apr 18 00:46:47 1996
From: [e-mail] (Tom Bruhns)
Newsgroups: rec.radio.amateur.antenna
Subject: Re: Average Current on Ladder-Line
Date: 15 Apr 1996 17:59:42 GMT
Message-ID: <4ku2qe$[e-mail]>
References: <4klg9v$[e-mail]>

jaeschke ([e-mail]) wrote:

: You mentioned the phase relationship between the reflected and
: forward currents in a line.  I am wondering what would be the
: phase if you can tell me easily if the load is resistive, but
: not matched to the ZO of the line?  Intuitively, I would
: think that it would be 0 since the reflection coefficient is
: real.

Well, either zero or 180 degrees.  It depends a little on
definitions:  Let's say that the forward and reflected waves
are in phase _at_a_particular_point_ on the line if their
voltages are the same polarity, measured the same direction
across the line (like if you call the outer conductor of the
coax "common" for both).  (It would be kind of perverse to
NOT define them that way, I guess, but it's always best
to state things like that up front!)

Anyway, if the load is a resistance R then

  if R > Z0
    then the voltage at the load must be greater than
    the voltage of the forward wave, and that means the
    reverse wave must be in phase with the forward wave
    at the load.  (Note:  in this case, the voltages
    add and the currents subtract, since the fwd wave
    and reverse wave currents are going opposite directions.)

  if R < Zo
    then the voltage at the load must be less than the
    voltage of the forward wave, and that meand the
    reverse wave must be 180 degrees out of phase with
    the forward wave at the load, etc.

  if R = Z0
    then the current in the load is exactly the same as
    the current in the line from just the forward wave,
    and there is no reverse wave required to support that
    condition at the load end of the line.

Long, long ago, the radio club that helped me get my license
used to scout out any free films that could be shown at
meetings, and we got some that I think came from Bell Labs.
They showed graphical demonstrations of transmission lines.
The lines were rods, with cross pieces every inch or so.
They were used in a torsional mode.  The ends of the cross
pieces were painted white, so you could easily see a wave
travelling down the line.  And you could see what happened
at transitions and at loads.  You could terminate the line
in an "open" or a "short" (let the end float free, or tie
it solidly down).  The vivid images these films left have
made it easy for me to figure out line problems involving
transmission and reflection.  I wish any ham wondering about
lines could see these films, but I have no idea if they
are available, or if they got transferred to video, or what.


--
Cheers,
Tom
[e-mail]


From [e-mail] Thu Apr 18 00:46:47 1996
From: [e-mail] (Mike Pappas)
Newsgroups: rec.radio.amateur.antenna
Subject: Re: Best Antenna Design Program?
Date: Tue, 16 Apr 1996 16:35:36 -0400
Message-ID: <[e-mail]>
References: <4ki7n1$[e-mail]> <4kjf34$[e-mail]>

Folks,

Anyone know of a Mac antenna design program and where I can get it from?
One that can generate the dimensions for gamma matching would be very
helpful.

Thanks

Mike Pappas
Engineering Manager
KUVO Public Radio
[phone]

--
Mike Pappas
Pappas Consulting


From [e-mail] Thu Apr 18 00:46:48 1996
From: (Gary) (KF9CM) [e-mail]
Newsgroups: rec.radio.amateur.antenna
Subject: Best mobil antenna program?
Date: 17 Apr 1996 12:07:23 GMT
Message-ID: <4l2mtr$[e-mail]>

I have tried an older Elnec program for modeling mobil antennas and it treets
the
inductor as a lumped inductance.  This does not take into account the "Q" of t
he
coil.  Is there a program that takes in the special considerations of mobil an
tennas
or shortened antennas?


                                        TNX Gary KF9CM



From [e-mail] Thu Apr 18 00:46:50 1996
Newsgroups: rec.radio.amateur.equipment,rec.radio.amateur.antenna
From: [e-mail] (Gary Coffman)
Subject: Re: Coax Shield Current (Was Re: MFJ Artificial Ground)
Message-ID: <[e-mail]>
Reply-To: [e-mail] (Gary Coffman)
References: <4k43ol$[e-mail]> <4ke5il$[e-mail]> <[e-mail]> <4kihkr$[e-mail]> <4kn142$[e-mail]>
Date: Sat, 13 Apr 1996 23:44:16 GMT

In article <4kn142$[e-mail]> [e-mail] (M
ike McCarty) writes:
>In article <4kihkr$[e-mail]>,
>WB3U <[e-mail]> wrote:
>)This does not mean that voltage is not a substance, however.  I used
>)the phrase "essential essence" intentionally, as this is the very
>)first definition of "substance" according to my copy of Webster's.
>
>Voltage is not a substance. It is a name for the UNIT OF MEASURE (like
>"inch") for the ElectroMotive Force (EMF).

Yeah, sort of, but that's not telling the essence. It certainly gives
the wrong impression. The volt isn't a unit of force, it is a *work*
function that measures how much work it takes to move one coulomb of
charge a specific distance against a specified field gradient. It has
units of J/C (joules per coulomb). Work is, of course, force*distance,
so force is certainly part of what constitutes the volt, but so is
distance, the two end points locating Vab or the *potential difference*
of the field gradient across which you are measuring. Thus the volt has
no meaning unless it is measured between *two* points. There can be no
naked potential.

You always have to ask, "relative to what?" when talking about the voltage
at a certain point. And you are perfectly free to choose that "what" to
be any point you like, and you'll get a different voltage for every different
"what" you choose (assuming the points chosen don't form an equipotential
surface around the other point). However, if you don't choose the "what"
carefully, the voltage you read may be meaningless to the circuit in
question. That "what" has to be another point through which the charge
represented by the coulomb part of the volt can move, IE the point must
be inside the topology of the circuit where Kirchhoff's laws hold, if
it is to have any meaning to the circuit. In such a circuit, charge
must be conserved.

Gary
--
Gary Coffman KE4ZV          |    You make it,     | Due to provider problems
Destructive Testing Systems |    we break it.     | with previous uucp address
es
534 Shannon Way             |    Guaranteed!      | Email to [e-mail]
Lawrenceville, GA 30244     |                     |


From [e-mail] Thu Apr 18 00:46:51 1996
From: [e-mail] (WB3U)
Newsgroups: rec.radio.amateur.equipment,rec.radio.amateur.antenna
Subject: Re: Coax Shield Current (Was Re: MFJ Artificial Ground)
Date: Sun, 14 Apr 96 20:19:31 GMT
Message-ID: <4kru6j$[e-mail]>
References: <[e-mail]> <4kmu2o$[e-mail]>

   [e-mail] (Tom Bruhns) wrote:

>But I do have a problem about "potentials attracting" (or repelling)
>each other.  It's the charged particles that interact with each other
>through electrostatic and dynamic forces.

Hi Tom,

This terminology is not an uncommon means of viewing and analyzing
a circuit.  In my case, it's the result of thousands of hours of
schematic analysis and equipment troubleshooting.  Like others in the
field, I have found that this language not only provides a perspective
unencumbered by particle theory, it is universally understood.

The process of analyzing and troubleshooting equipment at the
component level is not too different from the exercise we have been
involved with here.  In addition, because the audience is diverse and
because particle theory is mostly unnecessary to gaining an
understanding of the circuit, I chose this particular wording.

Gary also took exception to my use of this terminology, but for less
valid reasons than yours.  Because his own statements regarding the
circuit were (and continue to be) severely flawed, he chose to shift
the focus from the ongoing analysis to terms and definitions.
Unfortunately, a review of the "correction" to my statements reveals a
set of definitions and explanations that could not possibly be applied
without bringing the discussion of shield current to an immediate and
chaotic halt.  That was, of course, the intended result.  Readers left
without an understanding of the circuit would remain unable to discern
fact from fiction, or more to the point, to associate each with its
respective author(s).

As a side note, in the many years that I was involved in equipment
service, the worst examples of "butchered" equipment came at the hands
of two groups; those with inadequate electronics exposure and
experience, and electrical engineers.  For the latter, it's my
opinion that in many cases their professional skills were geared to
finer pursuits, and that simply put, the individual was often unable
to see the forest for the trees.

I don't mean to demean the engineering profession with this comment,
nor do I mean to stereotype all engineers.  I have met many engineers
who were expert at both design and failure analysis, as well as those
who could do neither.  Rather, I only mean to say that the skills each
of us acquires are usually most effective when applied to their
intended endeavors.

So it goes with terminology and I maintain that the wording I used was
appropriate to both the general audience and the analysis.  Any
attempt to disassemble the inner workings of the circuit at the
particle level is not only unnecessary, but potentially destructive to
the purpose of the discussion.

It is hoped that you and others will consider my description in the
context of the nature of the discussion at hand, and will not take
offense.  In all honosty, had this thread been an exercise to acquaint
readers with the Artificial Ground or shield currents through particle
analysis, I would not have bothered to even get involved.  Such a
discussion would be far too silly and far too useless to be worth
anyone's time or effort.  ;)

73,
Jack WB3U


From [e-mail] Thu Apr 18 00:46:53 1996
From: [e-mail] (W8JI  Tom)
Newsgroups: rec.radio.amateur.antenna
Subject: Re: Coax Shield Current (Was Re: MFJ Artificial Ground)
Date: 14 Apr 1996 01:48:25 -0400
Message-ID: <4kq3j9$[e-mail]>
References: <4knd0c$[e-mail]>

Hi Gary,
In article <[e-mail]>, [e-mail]
(Gary Coffman) writes:

>There's no way you can get around the fact that current goes to zero
>at the open end of an antenna, Jack. There's no place further for it
>to go, it has to stop there and be reflected

That is true Jack. Current goes to zero.

>So, both antennas have a fixed high impedance at the top that cannot
>be changed. Now applying wave reflection theory, that means that 90
>degrees down from the top will be a current maximum/voltage minimum,
>and hence a low impedance point. Has to be, it's the law. Now 180
>degrees down from the top, wave reflection theory tells us we must
>have another current minimum and voltage maximum, a high impedance,
>have to, there's no choice, it's the law.

Not at all. First we have to define what you call impedance at this moment
in time. As this snake wanders around I'm not sure what thee definition of
the moment is. At first the structure was shunt fed, now I'm not so sure.

If it is the series impedance, Eznec predicts the following at each point
given as a percentage of height on a 1/2 wave freespace resonant conductor
grounded at one end: 80%=25 -j647, 65%=123 -j813, 50% 2654 -j229, 35% 385
+j694, 20% 309 +j529.

There is no current maximum at the middle unless the antenna is series
base fed. In that case it's an insulated tower, not a grounded one. When
fed in the middle it will actually have two current maxima offset from the
middle. Don't take my word, it's EZ to model on EZnec.

> So the bottom of a halfwave
>vertical is a high impedance. No matter what it is connected to at the
>bottom, it can't supply current to it because it is at a current
>minimum, is a high impedance source, and practically nil current
>can flow. Has to, it has no choice, it's the law.

It must be a private law, because models and long-hand analysis prove
otherwise in the case of a grounded base half wave that isn't series fed
at or near the bottom.

>So what? There's nothing, repeat nothing, magic about ground (dirt).
>It's just a poor conductor that happens to be large.

Are we using a very lossy media? I thought it was a ground, as in "the
base of the antenna is grounded". If it is a connection to a very lossy
media, define it.

>Not just wrong, but dead wrong. Current will be maximum halfway down
>the 1/2-wave antenna, just as the little diagrams in the antenna
>books show it to be, just like they show current to be minimum at
>top and bottom. Has to, can't do anything else, it's the law.

Not if the bottom is grounded. Unless it isn't really grounded, it's two
inches deep in dry pure silica.

>And you have made me very happy I'm on this side (impedance at the
>open end of a resonant halfwave antenna low indeed! chortle, snort)
>I'd like to see Tom's face when he reads all this. :-)

Such childish remarks! Does that stuff really help your technical point
Gary? Shame on you, you're smart enough to make a point without remarks
like that, aren't you?

If the system isn't defined correctly any analysis will be flawed. Define
the system.

73 Tom


From [e-mail] Thu Apr 18 00:46:54 1996
From: [e-mail] (WB3U)
Newsgroups: rec.radio.amateur.equipment,rec.radio.amateur.antenna
Subject: Re: Coax Shield Current (Was Re: MFJ Artificial Ground)
Date: Sun, 14 Apr 96 08:18:38 GMT
Message-ID: <4kqjup$[e-mail]>
References: <[e-mail]> <4kiuge$[e-mail]> <[e-mail]> <4klhk7$[e-mail]> <[e-mail]>

The ARRL Antenna Book states that a 1/4 wave feedline (or odd
multiple) will minimize antenna currents when "the coupling apparatus
is grounded at the transmitter."  It further states that "if the
transmitter has fairly large capacitance to ground, a system of this
length will be effectively detuned for the fundamental and all even
harmonics when grounded to the transmitter at the coupling apparatus."

Gary, this contradicts most of your claims relating to shield length
and ground.  It deserves your comments.

73,
Jack  WB3U


From [e-mail] Thu Apr 18 00:46:55 1996
From: [e-mail] (Rob Whitacre)
Newsgroups: rec.radio.amateur.equipment,rec.radio.amateur.antenna
Subject: Re: Coax Shield Current (Was Re: MFJ Artificial Ground)
Date: 15 Apr 1996 14:07:10 GMT
Message-ID: <4ktl6e$[e-mail]>
References: <4kaua0$[e-mail]> <4ke5il$[e-mail]> <[e-mail]> <4kjhck$[e-mail]> <[e-mail]> <4kp6oh$[e-mail]>

In article <4kp6oh$[e-mail]>, [e-mail]
says...
>
>>[e-mail] (WB3U) writes:
>  [e-mail] (Gary Coffman) wrote:
>
>>>What you've missed is that current drawn from those two poles is
>>>forced to be equal and opposite by the inherent nature of the fields
>>>inside the coax.  Therefore, regardless of the load at the far end
>>>of the coax, the load seen by the transmitter itself is *always*
>>>balanced at both poles.  Nothing is attempting to draw more current
>>>from one pole than the other, therefore there is no need for any
>>>"return" current in order to balance the transmitter.  **This
>>>condition is satisfied whenever coax is attached to the
>>>transmitter.**
>
>>Ok, so if we believe this,
>
>Gary, if you don't believe that the currents on the inside of the coax
>are forced to be equal and opposite by the internal fields, we can
>stop here.  This is one of the basic attributes of coax and you should
>address this issue for yourself post haste.
>


Jack is absolutely right here about the coaxial transmission line. The
mathematics of the situation requires the current to be equal and opposite on
the inner conductor and inside of the outer conductor.  At the load end some
sort of impedance is connected between these two points. Part of this
impedance could be a path which includes the outside of the coax. This does
not upset any fundamental laws or require any other current sources.  This
can be difficult to visualize, but that doesn't mean we should change
electromagnetic theory.

Rob WB8WQA



From [e-mail] Thu Apr 18 00:46:57 1996
From: [e-mail] (W8JI  Tom)
Newsgroups: rec.radio.amateur.antenna
Subject: Re: Coax Shield Current (Was Re: MFJ Artificial Ground)
Date: 16 Apr 1996 01:02:53 -0400
Message-ID: <4kv9lt$[e-mail]>
References: <4kq22m$[e-mail]>

In article <4ktl6e$[e-mail]>, [e-mail] (Rob
Whitacre) writes:

>
>Jack is absolutely right here about the coaxial transmission line. The
>mathematics of the situation requires the current to be equal and
opposite on
>
>the inner conductor and inside of the outer conductor.  At the load end
some
>sort of impedance is connected between these two points. Part of this
>impedance could be a path which includes the outside of the coax. This
does
>not upset any fundamental laws or require any other current sources.
This
>can be difficult to visualize, but that doesn't mean we should change
>electromagnetic theory.
>
>Rob WB8WQA

Another good explaination. Right on Rob!

73 Tom


From [e-mail] Thu Apr 18 00:46:58 1996
Newsgroups: rec.radio.amateur.antenna,rec.radio.amateur.misc
From: [e-mail] (Pete Soper)
Subject: Different(ial) RFI Problem: partial solution
Date: Mon, 15 Apr 1996 17:06:10 GMT
Message-ID: <[e-mail]>
References: <4kpd74$q2o$[e-mail]> <4kquoh$[e-mail]>

A while back I posted an article to the Antenna group describing how
the 100 watts from my HF rig through a G5RV or 20m Lazy-H was
coupling into my stereo speaker leads. The RF found its way to the
front of one of the amp stages, getting demodulated in the process,
and the result was audio out of the stereo's amplifier independent of
its volume control setting. Disconnecting the speakers and listening
via headphones confirmed that it was the speaker connections allowing
the RF through (in contrast with the problem affecting Mike, WB2TBQ,
where the AC line cord is the path into his stereo).

I tried various common mode chokes, including seven of the Radio Shack,
snap together rectangular filters. I also tried smaller gauge wire
wound bifilar around some Amidon FT-50A-75 toroids. No dice: the RF
current appears to be differential, not common mode.

Using the same toroids wound as inductors I made low pass filters for the
speaker leads and this cured my problem on 15, 17 and 20 meters. The
problem remains on 40 meters. I'm hopeful that by tweaking the filter
parameters a bit to get the cutoff frequency down lower I'll get enough
attenuation on 40 meters to have a complete cure.

What I'm currently using is a series 12uh inductor (5 turns of hookup wire
around the above toroid) with .1uf parallel capacitors on either side of
the inductor.

I started out with about 40uh (9-10 turns) but found this caused a
strange kind of distortion of the stereo sound when playing music. It
didn't chop the highs as I expected if I got the cutoff too low. Instead
it caused a scratchy, harsh distortion. I was quite surprised by this
effect, as 40uh would seem to be neglible to the stereo amp at audio
frequencies in comparison to the inductance of the speakers themselves.
I wonder what is happening here?

Also, the above toroids are the ones spec'd in a telephone RFI article
from QST some time ago (past year or two I think). With the number of bifilar
turns of magnet wire (and the same gauge) specified in the article, the
phones in my house were disabled by this filter. It was as if the phone
was off hook. Tests showed I didn't have a DC short and three
different phones suffered the same effect. For the next experiment I'll
be removing turns until the disruption goes away, then checking to see if
there is enough common mode filtering left to give my wife relief from
my noise.

To the wordy regulars of the Antenna Usenet group (and you know who you are):
WOW, I sure have been getting an education reading your stuff. Thanks, guys!

Regards,
Pete
KS4XG


From [e-mail] Thu Apr 18 00:47:00 1996
Newsgroups: rec.radio.amateur.antenna,rec.radio.amateur.misc
From: [e-mail] (Pete Soper)
Subject: Re: Different(ial) RFI Problem: partial solution
Date: Wed, 17 Apr 1996 20:59:35 GMT
Message-ID: <[e-mail]>
References: <4kpd74$q2o$[e-mail]> <4kquoh$[e-mail]> <[e-mail]> <[e-mail]>

[e-mail] (Gary Coffman) writes:

>Sounds like a parasitic oscillation in the stereo audio PA. Try putting
>a resistor across the coil (start with 1k and work down) and see if that
>stops the distortion.

Thanks for the feedback, Gary (no pun intended).

Jack, WB3U pointed out that I had a lot more inductance than I thought.
My Autek RF-1 said one thing, the Amidon "AL" value for the toroid I
used said quite another. After more careful listening it turned out I
was clipping highs out of the audio and there was still some distortion,
even with the 5 turns on the cores. Jack speculates the distortion
might be core saturation.

So this is all bad news, as it means the three pole filter isn't going
to do the job for eliminating the RFI on 40 meters and in fact might
not cure it on the higher bands if I adjust the cutoff to not mess up
the audio.

My strategy now is this: air core coils, 4 poles or more, find something
that works very well with one channel, then consider ferrite with a lower
permeability if the size of the coils is an issue. I may have to filter
all five channels (surround sound system) and the minibox I chose looks
like it might get very dense now! Oh, and trust the Amidon charts, not
my Autek for inductance values (darn!). If I get distortion with air
cores I'll try your resistor mod.

One additional question I raised with Jack: If this really is a differential
mode RFI problem, is the stereo receiver's AC line likely to be providing
a return path, and if so, should I try aggressively filtering it?
I could put some very serious filtering in place on the AC feed before
my violin strings sounded like power tools :-)

Regards,
Pete
KS4XG


From [e-mail] Thu Apr 18 00:47:01 1996
From: [e-mail]@sp.rp.collegebdeb.qc.ca    (Pierre Tremblay)
Newsgroups: rec.radio.amateur.antenna
Subject: Re: FM Station far away
Date: 16 Apr 1996 00:32:20 GMT
Message-ID: <4kupqk$[e-mail]>
References: <[e-mail]>
Reply-To: [e-mail]

In <[e-mail]>, [e-mail] (Matthew White) writes:
>To Amateur Antenna:
>
>       I currently live in the New York, NY vicinity and would like to be
>able to listen to a radio station that is located in Phildelphia, PA
>-- 96.5FM to be exact...
>
>       Does anyone know how I could listen to this radio station with very
>little ease (i.e., buy a very powerful antenna or something) because
>I do not have the ability to place a tower out my window for I rent
>an apartment currently...
>
>snip

Even with a tower and a powerful antenna I don't think you could receive a
FM station 100 miles away very well. 100 MHz only gives you line of sight prop
agation
and without digging out any big books I say you're below the horizon....


From [e-mail] Thu Apr 18 00:47:02 1996
From: [e-mail] (Martin Rask)
Newsgroups: rec.radio.amateur.antenna
Subject: Re: GAP Titan DX
Date: 15 Apr 1996 23:36:59 GMT
Message-ID: <4kumir$[e-mail]>
References: <[e-mail]> <4kd52n$[e-mail]>

In article <4kd52n$[e-mail]>, [e-mail]
says...
>
>[e-mail] wrote:
>
>>Anybody have any experience with the Titan DX.  I have limited
>>space and am thinking about this antenna.
>
>>Please Email Reply!
>>Thanks Paul
>
>>[e-mail]
>
>Hi!
>I helped a friend to put together a Titan this weekend. It works
>BEAUTIFUL!!!  No tuning. It outranged two other verticals and had far
>less background noise than the longwire. Even though it is not
>designed for 160m it was 3 to 4 S-units better on 80, 40, 20 meter and
>tuned with the matchbox it still was better than the longwire on 160m.
>I'm seriously thinking about replacing my maldol 5-band vertical with
>a Titan. But that will have to wait as a present to myself when I have
>uppgraded my licence! It sure melps my practice with the CW.
>
>Oh, one more thing, I don't sell antennas!!
>
>73 es cu on the band    SM7PAF / Tommy
>
Hej Tommy.. Sσ din artikell i Antenna.. TΣnkte fσrga lit hur den
funkade.. Σr de som de stσr i reklamen.. bara att sΣtt ihop och k÷ra ??
igen SWR.. igen instΣllning ??
hur verkade aluminumet ?? klent eller tror du att de hσller f÷r vintrar
med sn÷ !! HI.. 73 de SM7VHS Martin

Email [e-mail]



From [e-mail] Thu Apr 18 00:47:03 1996
From: [e-mail] (Dale Chidester)
Newsgroups: rec.radio.amateur.antenna
Subject: Re: Hamsick or Outbacker?
Date: 10 Apr 1996 12:41:35 GMT
Message-ID: <4kga9v$[e-mail]>
References: <[e-mail]>
Reply-To: [e-mail]



In article [e-mail], [e-mail] (Steve Ellington) writes:
>Better value??? Well, dosen't the Perth cost nearly $300? My hamstick cost
>$19.95. I only operate 40 meter cw mobile anyway. I use a little MFJ tuner
>at the rig. You may also put a 500pf cap from the base of the antenna to
>ground to help match it. That's one thing I don't understand is why these
>mobile antennas aren't matched to begin with. After all, the
>advertisements don't say anything about this problem.
>
>
>--
>Steve Ellington [e-mail]  Louisville, Ky

With regard to the matching, did you adjust the whip part to resonance at the
desired operating frequency?  You can't expect a resonant antenna to be matche
d
across the entire band, but you can hava a reasonable match (< 2:1) over a cou
ple
of hundred kHz.  I adjusted my hamstick to 7.225 MHz with an SWR of less than
1.2:1

73,
        Dale


------------------------------------------------------------------------
Dale H. Chidester, PhD           N3HAL      "Against stupidity, even the
Cyanamid Agricultural Research Center        Gods in vain doth contend."
Process Development Facility                                    Schiller
PO Box 400,  Clarksville Rd.           Phone: [phone]
Princeton, NJ  08543-0400              Email: [e-mail]
------------------------------------------------------------------------




From [e-mail] Thu Apr 18 00:47:04 1996
From: [e-mail] (Derrick Cole)
Newsgroups: rec.radio.amateur.antenna
Subject: Hamstick Dipole Taken to Next Level?
Date: 15 Apr 1996 01:07:39 GMT
Message-ID: <4ks7gr$[e-mail]>

Greetings, all!

The Hamstick dipole is doing great!  Even had some positive QSO comments from
some folks regarding it!

I'd like to now explore the possibility of mounting multiple 'Stick dipoles
on a single mast.  Any foreseeable problems with such an idea?  Given the
mounts I currently possess, each separate dipole would have to be
individually fed.

At the Raleigh HamFest today, however, I got to thinking: what of a single-fed
"band-selectable" family of dipoles?  I would surmize the same principles
utilized with multi-band wire dipoles apply.

73 de KC4WEJ,
Derrick


From [e-mail] Thu Apr 18 00:47:05 1996
From: Nick Reddish <[e-mail]>
Newsgroups: rec.radio.amateur.antenna
Subject: Hokushin - GP5V antenna
Date: Mon, 15 Apr 1996 10:35:17 -0700
Message-ID: <[e-mail]>

I'm looking to source a part for a Hokushin GPV5 antenna. Does anyone
know the telephone/address of Hokushin and/or a distributor for their
products.

Many Thanks
--


Nick Reddish (G0ORE)
Systems Engineering Consultant.
Data General, UK.


From [e-mail] Thu Apr 18 00:47:06 1996
From: [e-mail] (Cecil A. Moore~)
Newsgroups: rec.radio.amateur.antenna
Subject: Re: Ladder line length
Date: 12 Apr 1996 16:16:15 GMT
Distribution: world
Message-ID: <4klvkf$[e-mail]>
References: <4k0vjm$[e-mail]> <[e-mail]> <4ke4rv$[e-mail]> <4kgp5a$[e-mail]>

In article <4kgp5a$[e-mail]>, Kevin Schmidt  <kschmidt> wrote
:
>
>One way to produce a big "velocity factor" is resistive loading.

Hi Kevin, I've been assuming that if the first bead gets the hottest,
then it is indeed acting like a resistor. I can't think of any other
way to account for it. You say "one way". Can you suggest another way?

73, Cecil, KG7BK, OOTC  (not speaking for my employer)




From [e-mail] Thu Apr 18 00:47:07 1996
From: John Fleming <[e-mail]>
Newsgroups: rec.radio.amateur.antenna
Subject: Re: Loading up a Skyscraper
Date: Mon, 15 Apr 1996 08:25:06 +0500
Message-ID: <[e-mail]>
References: <4kose6$[e-mail]>

Charlie,

With a sense of humor like yours, don't worry, I wouldn't be working for
you.

John N9NDH

CHARLES J. MICHAELS wrote:
>
>  ohn Fleming ([e-mail]) wrote:
> : I work in downtown Chicago in a very large skyscraper.
> : I am unfortunately in the middle of the floor, with no access to
> : a window. I occasionally have the urge to DX from my high-storied perch.
> : I can't, of course, because I'm downtown and in the middle of the floor
> : and would have to have a really small QRP transceiver and keyer/paddle
> : that no one could see, and plug in earplus so no one could hear,
> : BUT.
>
> If I were his boss he would be operating mobile from the sidewalk.
>
> Charlie, W7XC
> --


From [e-mail] Thu Apr 18 00:47:08 1996
From: [e-mail] (David L. Thompson)
Newsgroups: rec.radio.amateur.antenna
Subject: Re: Looking for OM experienced on half-loop antenna on 80
Date: Sun, 14 Apr 1996 03:24:58 GMT
Message-ID: <4kpu6k$[e-mail]>
References: <4khc9f$[e-mail]>
Reply-To: [e-mail]

Mio Nome <[e-mail]> wrote:

>For my 80 m activity I'm using now a half-sloper, but I'm not very satistacte
d from the results. I read about the half-loop antenna. Is there anyone experi
enced on this kind of antenna? Or is there anyone suggesting something to impr
ove the effectiveness of half-sloper?
>TNX for helping me.

>                                  73 de Aldo IK2ANI

I have used and designed half loops for 160.  The design I use is not
the half loop that Belrose and others use, but one that fully makes
use of the top half of the loop to transmnit and the image to get a
low angle.  The 160 half loop is 65 feet vertical, 130 to 135 feet
horizontal, and again 65 feet vertical.  You need at least 4 radials
at each end and then tie the two radials together with a wire.  The
160 is fed at the bottom of either 65 foot down leg and is somewhat
oval with slight max radiation endfire to the feed point leg.

The 160 is a multi band antenna which we have used successfully for
mult stations in Multi op.

An 80 meter version would be roughly 1/2 that size.  Keep away from
houses and try to keep at least 10 feet from a tower.

Good luck es 73,

Dave K4JRB




>




From [e-mail] Thu Apr 18 00:47:09 1996
From: Mio Nome <[e-mail]>
Newsgroups: rec.radio.amateur.antenna
Subject: Re: Looking for OM experienced on half-loop antenna on 80
Date: 13 Apr 1996 21:12:01 GMT
Message-ID: <4kp5b1$[e-mail]>
References: <4khc9f$[e-mail]>

> For my 80 m activity I'm using now a half-sloper, but I'm not very satistact
ed from the results. I read about the half-loop antenna. Is there anyone exper
ienced on this kind of antenna? Or is there anyone suggesting something to imp
rove the effectiveness of half-sloper?
> TNX for helping me.
>
>                                   73 de Aldo IK2ANI
>
>
>
>
>
>
>



From [e-mail] Thu Apr 18 00:47:10 1996
From: [e-mail] (W8JI  Tom)
Newsgroups: rec.radio.amateur.antenna
Subject: Re: MFJ Artificial Ground
Date: 14 Apr 1996 01:22:30 -0400
Message-ID: <4kq22m$[e-mail]>
References: <[e-mail]>

Hi Gary,
In article <[e-mail]>, [e-mail]
(Gary Coffman) writes:

>There's no way you can get around the fact that current goes to zero
>at the open end of an antenna, Jack. There's no place further for it
>to go, it has to stop there and be reflected

That is true Jack. Current goes to zero.

>So, both antennas have a fixed high impedance at the top that cannot
>be changed. Now applying wave reflection theory, that means that 90
>degrees down from the top will be a current maximum/voltage minimum,
>and hence a low impedance point. Has to be, it's the law. Now 180
>degrees down from the top, wave reflection theory tells us we must
>have another current minimum and voltage maximum, a high impedance,
>have to, there's no choice, it's the law.

Not at all. First we have to define what you call impedance at this moment
in time. As this snake wanders around I'm not sure what thee definition of
the moment is. At first the structure was shunt fed, now I'm not so sure.

If it is the series impedance, Eznec predicts the following at each point
given as a percentage of height on a 1/2 wave freespace resonant conductor
grounded at one end: 80%=25 -j647, 65%=123 -j813, 50% 2654 -j229, 35% 385
+j694, 20% 309 +j529.

There is no current maximum at the middle unless the antenna is series
base fed. In that case it's an insulated tower, not a grounded one. When
fed in the middle it will actually have two current maxima offset from the
middle. Don't take my word, it's EZ to model on EZnec.

> So the bottom of a halfwave
>vertical is a high impedance. No matter what it is connected to at the
>bottom, it can't supply current to it because it is at a current
>minimum, is a high impedance source, and practically nil current
>can flow. Has to, it has no choice, it's the law.

It must be a private law, because models and long-hand analysis prove
otherwise in the case of a grounded base half wave that isn't series fed
at or near the bottom.

>So what? There's nothing, repeat nothing, magic about ground (dirt).
>It's just a poor conductor that happens to be large.

Are we using a very lossy media? I thought it was a ground, as in "the
base of the antenna is grounded". If it is a connection to a very lossy
media, define it.

>Not just wrong, but dead wrong. Current will be maximum halfway down
>the 1/2-wave antenna, just as the little diagrams in the antenna
>books show it to be, just like they show current to be minimum at
>top and bottom. Has to, can't do anything else, it's the law.

Not if the bottom is grounded. Unless it isn't really grounded, it's two
inches deep in dry pure silica.

>And you have made me very happy I'm on this side (impedance at the
>open end of a resonant halfwave antenna low indeed! chortle, snort)
>I'd like to see Tom's face when he reads all this. :-)

Such childish remarks! Does that stuff really help your technical point
Gary? Shame on you, you're smart enough to make a point without remarks
like that, aren't you?

If the system isn't defined correctly any analysis will be flawed. Define
the system.

73 Tom


From [e-mail] Thu Apr 18 00:47:12 1996
From: [e-mail] (Rane Curl)
Newsgroups: rec.radio.amateur.antenna
Subject: Re: MFJ Artificial Ground
Date: 16 Apr 1996 03:30:31 GMT
Message-ID: <4kv48n$[e-mail]>
References: <4kemch$[e-mail]> <[e-mail]> <4kn5n8$[e-mail]> <[e-mail]>

In article <[e-mail]>,
Gary Coffman <[e-mail]> wrote:
>
>Of course it does, it's an open circuit there. It has no choice. And
>*neither does the halfwave*. It's an open circuit at the top, so that
>has to be a high impedance point for it too. It can't be anything else.
>Current can't flow any further.
>
>So, both antennas have a fixed high impedance at the top that cannot
>be changed. Now applying wave reflection theory, that means that 90
>degrees down from the top will be a current maximum/voltage minimum,
>and hence a low impedance point. Has to be, it's the law. Now 180
>degrees down from the top, wave reflection theory tells us we must
>have another current minimum and voltage maximum, a high impedance,
>have to, there's no choice, it's the law. So the bottom of a halfwave
>vertical is a high impedance. No matter what it is connected to at the
>bottom, it can't supply current to it because it is at a current
>minimum, is a high impedance source, and practically nil current
>can flow. Has to, it has no choice, it's the law. The open circuit
>at the top *forces* the current into this distribution. There's
>nothing you can do at the bottom to change it.

Gary is correct. The point that has not been made in this exchange is
that, to talk about the impedance at the top, middle, or bottom (of
a half-wave radiator) you must posit a *generator* inserted into
the element. If the generator is at the middle, it will see a low
voltage and a high current (in phase, for a "tuned" radiator). However
if the generator is placed at the "grounded" end, one side is grounded
and the generator will produce low current and a high voltage. [If
the ground is perfect, what it will really look like is a full-wave
radiator driven at the center by virtue of being reflected across the
ground.]

An interesting contrast is viewing the "grounded" half-wave radiator
in an EM field. If we *define* the ground as zero potential (we have
no way to know otherwise, there being no other reference), the top
of the radiator will also be at zero (ground) potential *with respect
to the ground* and from that perspective we will observe maximum voltage
at the middle and *also* maximum current. This might at first seem
anomolous, but it only demonstrates the fact that currents *are*, but
voltages depend upon both points across which we measure them.

Rane L. Curl    N8REG


From [e-mail] Thu Apr 18 00:47:14 1996
From: [e-mail] (W8JI  Tom)
Newsgroups: rec.radio.amateur.antenna
Subject: Re: MFJ Artificial Ground
Date: 17 Apr 1996 01:34:26 -0400
Message-ID: <4l1vt2$[e-mail]>
References: <4kv48n$[e-mail]>

Hi Rane,

Gary was totally incorrect, there is no question at all about that.

Perhaps you missed the fact he defined the base of the antenna as being
grounded. By definition, that precludes use of a series feed system at the
base.

He also defined the antenna as "shunt fed". By definition that means the
base is grounded and the radiator is unbroken by insulators at any point.

In article <4kv48n$[e-mail]>, [e-mail]
(Rane Curl) writes:

>An interesting contrast is viewing the "grounded" half-wave radiator
>in an EM field. If we *define* the ground as zero potential (we have
>no way to know otherwise, there being no other reference), the top
>of the radiator will also be at zero (ground) potential *with respect
>to the ground* and from that perspective we will observe maximum voltage
>at the middle and *also* maximum current.

I am assuming the antenna is being illuminated by a far field source with
the electric field precisely parallel to the vertical element, and the
magnetic field transverse to the element. With the application of such an
EM field, this system appears as an electric field "short". With such an E
field "short", we know there can be no H field response either.

While it is true the top and bottom are at the same potential as "ground",
the middle is also at the same potential in reference to "ground", ALL
being zero. So this antenna, as originally defined by Gary, would work by
stub decoupling of the ground via the shorted quarter wave stub formed by
the shunt wire. As a grounded half wave long monopole excited by external
"broadside" EM fields, this antenna is a big zero.

If EM wave theory doesn't "work", just analyze this antenna as a
transmission line. The open top of the antenna causes a 180 degree current
inverting reflection, and the grounded base causes a 180 degree voltage
reflection. The voltage and current at the middle, top AND bottom, are ALL
zero when excited by a broadside parallel electric field and transverse
magnetic field. This antenna is a big nothing unless the radiator is
broken or decoupling of the base occurs via the feed method.

>This might at first seem
>anomolous, but it only demonstrates the fact that currents *are*, but
>voltages depend upon both points across which we measure them.

I don't think anyone doubted the simple facts of voltage and current,
Rane. The problem was the use of various conundrums during attempts to
validate theoretical misconcetions about functioning of very simple
systems. I can't think of a worse example in the world to explain antenna
theory than a grounded base half-wave vertical.

73 Tom


From [e-mail] Thu Apr 18 00:47:15 1996
From: [e-mail] (Diagonal Cafe)
Newsgroups: rec.radio.amateur.antenna
Subject: Need information about antenna book
Date: Mon, 15 Apr 1996 20:28:34 GMT
Message-ID: <4kuar5$[e-mail]>

Because of foreign vacation, I can't have access to the News Group
since two weeks.
I'm looking for this book:
 Engineering Compendium: HF Antenna Selection
 Rockwell-Collins 1969.

It would be great to receive an answer.

I am in the 1996 Call Book.
73,
Jacques Espiau, F5ULS.





From [e-mail] Thu Apr 18 00:47:16 1996
From: [e-mail] (WA6UBE)
Newsgroups: rec.radio.amateur.antenna
Subject: NVIS antenna test April 17,18,19
Date: 13 Apr 1996 12:19:31 -0400
Message-ID: <4kok6j$[e-mail]>
Reply-To: [e-mail] (WA6UBE)


Hello -
I will be setting up a portable hf station near Wateford california on
April 18th, and
19th in order to test G-tor with a military NVIS antenna system.

If you have an HF data station located within 400 miles of the
Modesto/Waterford, California area I would like to hear from you!!..

My station will consist of the following:
Sunair military HF SSB radio model GSB900DX running 50 watts
into a military NVIS antenna model AS2259/GR that has also been modified
to allow better performance on  the 1.6 to 4 MHz segment.

The station will be on generator power and I also plan to leave it up and
running in an un-attended
mode on the 80 meter band with a mailbox enabled.

If you are interested in running NVIS tests with me during this time
period, please e-mail me

Sincerely,

Patricia Gibbons <[e-mail]>
"The Vertical Skywave Girl"

[e-mail] "The Vertical Skywave Girl" ...
Mobile repair shop supervisor - City of San Jose/ GSA-Communications
voice-mail: 1-408-277-4082
PGP Public key available on request



From [e-mail] Thu Apr 18 00:47:16 1996
From: [e-mail] (Bostonian)
Newsgroups: rec.radio.amateur.antenna
Subject: RCA WT - 100A TUBE TESTER WANTED
Date: 14 Apr 1996 01:01:23 GMT
Message-ID: <4kpip3$[e-mail]>

RCA WT-100A and/or Hickok 700 tube tester wanted.  Seeking unit in good
running condition, needing some repairs or for parts (if I later come across
a working unit).  Willing to swap for something or please state a fair price
for the respective unit.  I would prefer swapping something as cash is tight,
but I would have to find out what you are looking for -- I may have it.
Please indicate if you have manuals, schematics, charts and/or plug-in tube
sockets for the respective tube tester.

Kindly, email with details.

Thank you.

Having email problems -- my correct address is:

[e-mail]


From [e-mail] Thu Apr 18 00:47:17 1996
From: [e-mail] (Anibal Aguirre)
Newsgroups: rec.radio.amateur.antenna
Subject: rRCA e-mail or www??????
Date: Mon, 15 Apr 96 10:36:07 EDT
Message-ID: <[e-mail]>
Reply-To: [e-mail]

hi friends:does anybody know RCA or RCA-VICTOR e-mail or www address???
It's for a question about RCA-VICTOR tac-200 rpt.
any help will be appreciated.

73 from Argentina.
                                          anibal aguirre
                                             LU4DVJ


--
---
E-mail: [e-mail]
Buenos Aires - Argentina




From [e-mail] Thu Apr 18 00:47:18 1996
From: Bob Gubbins <[e-mail]>
Newsgroups: rec.radio.amateur.antenna
Subject: screwdriver
Date: Sun, 14 Apr 1996 22:44:52 -0700
Message-ID: <[e-mail]>

Hi everyone I'm building a screwdriver antenna and have most of it done
but now I have to match the antenna to the feedline and I'm not sure how
to do it I've heard of adding cap's or torad's but not sure how or what
values.. thanks and 73's

de kb8vru


From [e-mail] Thu Apr 18 00:47:19 1996
From: (Gary) [e-mail]
Newsgroups: rec.radio.amateur.antenna
Subject: Re: screwdriver
Date: 17 Apr 1996 01:00:59 GMT
Message-ID: <4l1fsb$[e-mail]>
References: <[e-mail]>

>   Bob Gubbins <[e-mail]> writes:
>  Hi everyone I'm building a screwdriver antenna and have most of it done
>  but now I have to match the antenna to the feedline and I'm not sure how
>  to do it I've heard of adding cap's or torad's but not sure how or what
>  values.. thanks and 73's
>
>  de kb8vru
>
>>>>
I've been running a screwdriver antenna for about 2 years and I have found tha
t
1020 pF @ 3000v fixed for 80 meters and 750 pF for 40 metters.

                            I hope this helps you out

                                "73" KF9CM Gary <[e-mail]>



From [e-mail] Thu Apr 18 00:47:20 1996
From: [e-mail] (Alfred Lee)
Newsgroups: rec.radio.amateur.equipment,rec.radio.amateur.antenna
Subject: Re: The Transmitter Chassis
Date: 16 Apr 1996 09:41:04 -0700
Message-ID: <[e-mail]>
References: <4k43ol$[e-mail]> <4k4tth$[e-mail]> <[e-mail]> <4kbeqv$[e-mail]> <4kcftv$[e-mail]> <[e-mail]>

This has been the most educational thread I have seen in a long while.
Keep up the good discussion.

In article <[e-mail]>,
[e-mail] (Gary Coffman) wrote:
> In article <4kcftv$[e-mail]> [e-mail] (
WB3U) writes:

[deleted]

> >Now, considering that the AC voltage at the two output terminals of an
> >isolated generator will be equal amplitude and opposite phase, how can
> >the preceding be true?  Shouldn't the flange of the connector (and
> >thus the chassis of the transmitter) have the same RF voltage as the
> >center pin?  The answer is yes, it should, and if we perform the same
> >test with a solid-state mono *audio* amplifier, we would find that the
> >AF voltages on the chassis and on the "positive" output terminal are
> >in fact nearly identical.
>
> Yes, at *audio* frequencies, where *skin effect* doesn't come into
> play, this is true. But at RF, where skin effect does come strongly
> into play, the signal on the *inside* of the connector shell can't
> get to the outside of the connector shell, or the outside of the
> chassis. The thickness of those parts is several skin depths, so
> their insides and outsides are isolated from each other.
>

With so much talk about skin effect every where I have never seen
a figure being quoted.  I firmly believe some figures will put
discussions and understandings in perspective.  So here it goes:

    THE SKIN DEPTH AT 100 MHZ IS 0.66 uM (MICRON)

The variations due to different material is within an order of
magnitude.  If my memory failed me please quote the correct figure.
I think the number is so incredible that everyone should know.

[deleted]

>
> Gary
> --
> Gary Coffman KE4ZV          |    You make it,     | Due to provider problems

> Destructive Testing Systems |    we break it.     | with previous uucp addre
sses
> 534 Shannon Way             |    Guaranteed!      | Email to [e-mail]
> Lawrenceville, GA 30244     |                     |

On some previous posts RF current within the coaxial transmission line
and outside the shield were discussed.  The discussion centered on the
effect of line length, particularly at 1/4 wave length and 1/2 wave
length.  Doesn't the difference in velocity factors causes the current
maximum/minimum to occur at different location?  For RF current within
the coaxial line the V.F. is 66% (or some other number.)  For RF
current on the outside shield, due to the skin effect, the entire
cable might just as well as a solid conductor, for which the V.F.
is around 95%.  Wouldn't this effect make any difference?

73,

---
Alfred Lee                                                       [e-mail]
m
KE6KGV           'The answer is (e^iπ + 1) ? "No" : "Yes"'
Silent keys: KE6LTH, KD6HNU, March 22, 1996


From [e-mail] Thu Apr 18 00:47:23 1996
From: [e-mail] (WB3U)
Newsgroups: rec.radio.amateur.equipment,rec.radio.amateur.antenna
Subject: Re: The Transmitter Chassis (Was MFJ Artificial Ground)
Date: Mon, 15 Apr 96 21:46:19 GMT
Message-ID: <4kunli$[e-mail]>
References: <4k43ol$[e-mail]> <4k4tth$[e-mail]> <[e-mail]> <4kbeqv$[e-mail]> <4kcftv$[e-mail]> <[e-mail]>

It appears that the "Artifical Ground" thread may be about over.
Nevertheless, I wanted to repond to this particular post because it
describes several misconceptions regarding currents in and around
the typical HF transmitter chassis.  Sorry I didn't follow up sooner;
it didn't appear on my news server until earlier today.

      [e-mail] (Gary Coffman) wrote:
   >I wrote:

>>First, it was stated in the other discussion that feedline currents
>>radiate because they are unable to enter the transmitter and return
>>to their source.  I have disputed this because there are many
>>openings and pathways into the typical transmitter for current
>>flowing on the outer chassis.

>Any shielding that lets RF in, must also let RF out. Now I don't
>know about you, but I'd be real upset with a transmitter that
>leaked a lot of RF into the shack (if it did, I wouldn't *care*
>if RF also came back down the feedline because I'd already have
>a "hot" shack).

Leakage currents around the cabinet generally aren't detectable by
touch.  Even significant leakage won't usually cause the symptoms
associated with a "hot" shack.  The latter is the result of high RF
voltage, not current.  Also, in terms of radiation, the size of the
cabinet is only a small fraction of a wavelength.  It would require
an extraordinary amount of current to create notable symptoms.

>So I'd suggest that any leakage either way is going to be minute,
>which implies that the pathway through the shielding is a very high
>impedance.

I don't know what the actual impedance is, but I don't believe it's
very high.  It might be a few hundred ohms, but it certainly isn't
thousands of ohms.  Like I said before, the evidence of this is that
the appearance of voltage on the cabinet (such as results from common
mode feedline currents) often causes the transmitter to malfunction.
Sometimes this occurs long before the operator is even able to
physically detect the voltage, indicating that even moderate levels of
RF voltage on the cabinet can cause disruptive currents to flow into
the transmitter.

>I deleted the rest of your argument because it is premised on the
>outside of the chassis being at the RF potential of the inside of
>the chassis, which it isn't. If it were, you could take a transmitter
>up in a balloon and draw arcs from either the antenna or the chassis
>since there's no nearby Earth to unbalance it and make the outside of
>the chassis cold.  But you can't. The chassis is still cold up there
>far from Earth too.

No, it's not.  Measurement from any third point will show the voltage
on the chassis is nearly equal to the voltage at the feedpoint of the
antenna.

>But you *can* draw an arc from the end of *either* leg of a dipole
>fed by that transmitter,

Of course you can.  There's an impedance transformation along each leg
that steps the voltage up at the end.  Attach a 1/4 wave wire to the
chassis and the same thing will happen.

>showing that both the inner and the *inside* of the outer of the coax
>are hot.

None of this disproves the existence of a current path between the
inner chassis and the cabinet.

73,
Jack  WB3U


From [e-mail] Thu Apr 18 00:47:24 1996
From: Cecil Moore <[e-mail]>
Newsgroups: rec.radio.amateur.antenna
Subject: Re: tuner/balun
Date: 9 Apr 1996 17:46:35 GMT
Message-ID: <4ke7ps$[e-mail]>
References: <4ka8lt$[e-mail]> <4kcmpk$[e-mail]>

[e-mail] (W8JI  Tom) wrote:
>I measured just the opposite effect with baluns (some time ago).
>Our tuner loss measurements are close, if I used hi-Q settings.

One possible explaination might be if I have some
common mode currents. Common mode currents tend to cancel in
the 4:1 voltage balun. I assume they tend to heat up beads.
If the common mode currents see a high impedance with the 4:1
voltage balun and a low impedance with the beads, that could
explain my readings and also score a point for the voltage
balun. :-)  I didn't try to measure common currents.

73, Cecil, KG7BK, OOTC  (not speaking for my employer)




From [e-mail] Thu Apr 18 00:47:25 1996
Newsgroups: rec.radio.amateur.antenna
From: [e-mail]
Subject: Re: Tuning a copper J-Pole.
Message-ID: <[e-mail]>
Reply-To: [e-mail]
References: <4kt4iq$[e-mail]>
Date: Tue, 16 Apr 1996 01:26:15 GMT

In <4kt4iq$[e-mail]>, [e-mail] (Marine7) writes:
>I constructed a copper J-Pole for 2-meters, but I am unable to get the SWR
>below 3:1.    The SWR will go to close to 1:1 if I bend the stub toward
>the long pole, but then I get signal reports that indicate a hum that
>resembles a weak 60hz tone.  If I bend the stub back to parallel, the SWR
>goes up again to above 3:1.  Moving the feed line clamps up or down moves
>the SWR around, but not below 3:1.  I am new at the antenna building
>hobby, and would appreciate some tips concerning the tuning of,
>specifically, a copper J-Pole.
>
>Thanks, 73, Jim Temple, KF4ICZ.
You may have a problem with coupling between the antenna and your
feedline. Did you use a current balun (made by coiling 3-4 turns of your
feedline coax into an approx. one inch dia. loop, secured by electricians
tape, close to the feed point of your antenna)? I have done this and it does
make a difference in the swr.
I have built both the 2m j-pole and a 2m/70cm j-pole and have gotten
the swr down to approx. 1.2 to 1 (tested the 2m j-pole with two
different swr meters).
IMHO, the j-pole is a good home-brew antenna with good performance
and it doesn't cost much to build.

* John Vause  KF4ERV  [e-mail]                                  *
* Defenselessness is a crime which generates it's own punishment.   *
* The four boxes of Freedom: Soap, Ballot, Jury, and Ammo.           *





From [e-mail] Thu Apr 18 00:47:26 1996
From: Julius Oros <[e-mail]>
Newsgroups: rec.radio.amateur.antenna
Subject: Re: TV Antenna
Date: Tue, 16 Apr 1996 02:01:50 -0500
Message-ID: <[e-mail]>
References: <[e-mail]>
To: Gary Wagner <[e-mail]>

Gary Wagner wrote:
>
> I need to buy a directional TV antenna for my home.
                 Gary At list you seen one.
Why did not ask at the bar you seen it? Let me know how it is
look like. I just canceld my Cable. They are autrages and I geting
fabulus reception. To bad I don't have much experiance on Antennas.

TaTa.


From [e-mail] Thu Apr 18 00:47:27 1996
From: [e-mail] (Jim Garver)
Newsgroups: rec.radio.amateur.antenna
Subject: Re: Which is better on 80
Date: 15 Apr 1996 17:17:49 GMT
Message-ID: <4ku0bt$[e-mail]>
References: <4kjg9c$[e-mail]> <4k3sdl$[e-mail]> <4k5 <[e-mail]>

In article <[e-mail]>,
Don Phelps <[e-mail]> wrote:

>My best antenna on 80 was full length 135 ft dipole feed with
>450 ohm ladder line from a Johnson Matchbox.
>I used multiple conductors spaced 10 feet apart to widen
>the bandwidth and lower impedance swings.

>To lower losses in the ground reflection, I oriented the antenna
>vertically, hanging down from a tall limbless tree trunck
> which leaned over, all being on top of a knoll.

That is probably an excellent DX antenna on 80.  I would have to space my
antenna close to a tall fir tree to do that, but it might be worth it.
I don't like the low angle levels and pattern I get with dipoles on 80.

Does the close proximity of the ground to only one end of the dipole upset
the balance of the system and cause feedline radiation?  If you run an
amplifier any feedline radiation can cause havoc in the shack.

I currently have a 65' vertical up the side of a Cedar tree with a few
long radials.  This works okay, not great but it does do a good job of
attenuating the local signals while leaving the DX as strong or slightly
better than a 50' high dipole.  Attenuates local noise too.


WA7LDV
--
[e-mail]                             I don't speak for Intel


From [e-mail] Thu Apr 18 00:47:28 1996
From: Dan Nixon <[e-mail]>
Newsgroups: rec.radio.amateur.antenna
Subject: WTB: KLM KT34A Beam
Date: Sun, 14 Apr 1996 16:33:43 -0400
Message-ID: <[e-mail]>

Looking for the four (4) element KLM KT34A tribander. If you have one
and can ship it I would be interested. Also could meet you at Dayton and
pick it up there. Prefer one in good condition, although I am prepared
to refurbish one as necessary.
Dan, N4DVW, Atlanta, GA  [e-mail]


From [e-mail] Thu Apr 18 00:47:29 1996
From: cecil moore <[e-mail]>
Newsgroups: rec.radio.amateur.antenna
Subject: Re: Zepp, Double Extended - Why?
Date: 12 Apr 1996 21:49:02 -0700
Message-ID: <4knbnu$[e-mail]>
References: <[e-mail]>

[e-mail] wrote:
>Why has the standard
>advice always been to cut it longer than 1/2 WL?

Increasing the dipole length from 2 times 1/4 WL
to 2 times 5/8 WL theoretically increases the gain
by 3db just as it theoretically does with verticals.
Above 10/8 WL the pattern turns into a sometimes
useful cloverleaf pattern and then into a multi-
lobed pattern somewhat favoring the ends of the
dipole. It pays to know these patterns so your lobes
can be aimed in a useful direction. A DEZ has 3db
gain over a 1/2 WL dipole even though it has started
developing side lobes.

73, Cecil, KG7BK, OOTC




From [e-mail] Thu Apr 18 00:47:30 1996
From: [e-mail] (CHARLES J. MICHAELS)
Newsgroups: rec.radio.amateur.antenna
Subject: Re: Zepp, Double Extended - Why?
Date: 17 Apr 1996 20:05:44 GMT
Message-ID: <4l3iuo$[e-mail]>


Jack said -


Where is this "standard advice" you're referring to?  I've seldom seen
recommendations that a single-band dipole be anything other than 1/2
wavelength.

Jack,
        The only reason to make a dipole a resonant half wave long is
to get a pure resistive feedpoint impedance.

Charlie, W7XC
--


From [e-mail] Thu Apr 18 15:36:16 1996
From: Ed Hare <[e-mail]>
Newsgroups: rec.radio.amateur.antenna,rec.radio.amateur.homebrew,rec.radio.amateur.misc
Subject: Re: 1. Need Help With RFI Problems
Date: 17 Apr 1996 13:45:19 GMT
Message-ID: <4l2slf$[e-mail]>
References: <4kpd74$q2o$[e-mail]> <[e-mail]>
To: [e-mail]

[e-mail] (Gary Coffman) wrote:

>The FCC prints a pamphlet on RFI causes and cures, but it isn't
>very technical, oriented more toward the consumer. A better book
>on RFI causes and cures is offered by the ARRL.

The FCC's book is useful in one important regard -- it will help your
neighbor understand the difference between transmitter-caused
interference and consumer-equipment caused interference.  The ARRL also
has an "RFI Pamphlet," available from the Technical Department Secretary
for an SASE that says the same things (surprise!), but having it said in
the FCC's own words often carries more weight with your neighbor.  The
book is called "Interference to Home Electronic Entertainment Equipment
Handbook (CIB-2)."  It is available for $2.50 from: (I ordered it by name
with no difficulty.)

US Government Printing Office
Washington, DC 20402-9371
Phone: [phone]
202-512-1800 (credit card orders only)
Web Site: http://www.gpo.gov

ARRL also has several interference packages that will offer some fast
starter help.  Most are available electronically from the ARRL area at
oak.oakland.edu or from [e-mail].  Paper copies are available from
our Technical Department Secretary for $2.00 for ARRL Members, $4.00 for
non members.

We have the "RFI Pacakge," RFI-Telephone, RFI-TV, RFI-Audio,
RFI-Electrical and RFI-CATV.  The CATV package is available ONLY in paper
form; it is a reprint of an article I wrote for Communications
Technology, the journal of the Society of Cable Television Engineers.  (I
chose that instead of QST because I wanted something hams could hand to
their cable operator.  They trust CT more than they trust QST, for some
reason. :-)  ).

Our RFI book, Radio Frequency Interference is available from most ham
dealers, our Pub Sales Department, using the handy-dandy order form in
QST.  If you are an ARRL Member, you can get a bit of technical advice
before you buy the book by calling us at [phone].

73 from ARRL HQ,  Ed Hare, KA1CV, ARRL Laboratory Supervisor





From [e-mail] Thu Apr 18 15:36:16 1996
From: Perreau2 <[e-mail]>
Newsgroups: rec.radio.amateur.antenna
Subject: Re: 4BTV Vertical
Date: 18 Apr 1996 02:14:28 GMT
Message-ID: <4l48i4$[e-mail]>
References: <3172b5a0.0@nt_test.cacky.com>
To: [e-mail]

I think I have one somewhere...If you don't get a reply within a few days
send me an e-mail and I'll check and see for sure..

73's

Phil Perreault  [e-mail]



From [e-mail] Thu Apr 18 15:36:18 1996
From: [e-mail] (Bill Brannick)
Newsgroups: rec.radio.amateur.antenna
Subject: 80 Meter Helix
Date: Wed, 17 Apr 1996 20:19:24 GMT
Message-ID: <4l3k9s$[e-mail]>

Not happy with the performance of my 138 ft dipole (center-fed with
450 ohm open wire to a tuner). Does OK out to abt 750 miles or so..
but thats abt it.. I can hear a lot father then that but I cant get to
them, even with a little power.  Primary short coming, I suspect, is
the height of the dipole .. only abt 28-30 feet and I do not have a
way to get it any higher.

So.. was considering other possibilities... does anyone have any
design specs and anticipated performance comments on a vertical
helix...for 80 meters... I was think about winding abt 200 feet of
close spaced wire on a piece of 2-3/8" PVC and come off the the top of
it with another 70 feet or so as a sloper...

The highest I can goes with anything is about 35 feet.

Not sure what I should feed this thing with, either...

Any thoughts would be appreciated....

Afterthought.. wonder if it might work on 160 also... then again..
maybe it wont work on 80 either...

Just gropping around for ideas here...

Bill....KN6FJ



From [e-mail] Thu Apr 18 15:36:19 1996
From: Dan O'Connell <[e-mail]>
Newsgroups: rec.radio.amateur.antenna
Subject: Re: Antenna Design Web Pages Wanted
Date: Tue, 16 Apr 1996 14:09:44 -0700
Message-ID: <Pine.OSF.3.91.960416140520.27285C-100000@internet>
References: <4ks3mj$[e-mail]>



On Mon, 15 Apr 1996, Jerry Bath wrote:

> Does anyone know of any web pages that pertain to various antenna
> designs?

 I will, as soon as I get time to put the page together.( i now go to
college). most will be weak signal prima donnas for 144.0 to 144.250
ONLY, and some 6mtr stuff. none of that 50ghz bandwidth with 1:1 swr
stuff. I
spent a LONG time sitting in front of my computer on these things. Might
still be a while until I get the page together though. Dan O'Connell  WA7TDZ
    [e-mail]


From [e-mail] Thu Apr 18 15:36:20 1996
From: [e-mail] (John Kolb)
Newsgroups: rec.radio.amateur.antenna,rec.radio.amateur.misc
Subject: Re: Different(ial) RFI Problem: partial solution
Date: 18 Apr 1996 15:31:47 GMT
Message-ID: <4l5n93$[e-mail]>
References: <4kpd74$q2o$[e-mail]> <4kquoh$[e-mail]> <[e-mail]>

Pete Soper ([e-mail]) wrote:
: A while back I posted an article to the Antenna group describing how
: the 100 watts from my HF rig through a G5RV or 20m Lazy-H was
: coupling into my stereo speaker leads. The RF found its way to the

: What I'm currently using is a series 12uh inductor (5 turns of hookup wire
: around the above toroid) with .1uf parallel capacitors on either side of
: the inductor.


Try using much smaller capacitors. If you short the leads of a 0.1 uF
disc cap, and measure it with a grid dip meter, you may see it resonate
as low as 5 MHz. Above it's self resonant freq, it acts more like a
inductor than a cap. A C value more like 0.001 may work much better
for you, and have less effect on the audio also.

John Kolb  KK6IL  [e-mail]



From [e-mail] Thu Apr 18 15:36:21 1996
From: [e-mail] (WimberleyK)
Newsgroups: sci.electronics.design,rec.radio.amateur.antenna
Subject: Re: Earth to Sky Omnidir, Commercial?
Date: 17 Apr 1996 12:01:34 -0400
Message-ID: <4l34ku$[e-mail]>
References: <4krfbu$[e-mail]>
Reply-To: [e-mail] (WimberleyK)

Don't know for sure. But you might contact Celwave, Antenna Specialists,
or, possibly, Motorola Land Mobile Division.
Sorry. I don't know any addresses.
Good luck.


From [e-mail] Thu Apr 18 15:36:22 1996
From: Kevin Schmidt <kschmidt>
Newsgroups: rec.radio.amateur.antenna
Subject: Ethernet Terminator at UHF
Date: 17 Apr 1996 18:46:38 GMT
Message-ID: <4l3eae$[e-mail]>

I have a thinwire ethernet terminator that is stamped 50 ohms, 1 watt.
It is a more or less standard type built into a BNC plug. I wondered
what sort of dummy load it might be, so last night
I measured its impedance at 2-meters and 70 cm. I measured:

   48 -3j ohms at 146 MHz, SWR = 1.08
   46 -9j ohms at 435 MHz, SWR = 1.24.

If I believe these numbers, it looks approximately like a 48 ohm
resistor in parallel with a 1.5 pF capacitor. Do most ethernet
terminators have impedances and power ratings around this, or
am I just lucky (or unlucky)? Are there known better ethernet
terminators in terms of higher power ratings or lower SWR at UHF?

Before someone asks, my measurements were made with cheap hamfest 1950s
vintage boatanchor equipment (i.e. less than $100 total invested):
a General Radio 857 oscillator, 1602B admittance meter, and an
HP-417A superregen detector. The expected errors are a few percent
if the 1602B is in calibration.

Kevin Schmidt [e-mail]



From [e-mail] Thu Apr 18 15:36:23 1996
Newsgroups: rec.radio.amateur.antenna
From: Bob Lewis <[e-mail]>
Subject: Re: Hamsick or Outbacker?
Message-ID: <[e-mail]>
Date: Tue, 16 Apr 1996 15:35:15 -0400
References: <[e-mail]> <4k0ruv$[e-mail]> <[e-mail]> <[e-mail]>

Steve Ellington wrote:
>
> Better value??? Well, dosen't the Perth cost nearly $300? My hamstick cost
> $19.95. I only operate 40 meter cw mobile anyway. I use a little MFJ tuner
> at the rig. You may also put a 500pf cap from the base of the antenna to
> ground to help match it. That's one thing I don't understand is why these
> mobile antennas aren't matched to begin with. After all, the
> advertisements don't say anything about this problem.
>
> --
> Steve Ellington [e-mail]  Louisville, Ky

I use a 2:1 UNUN (broad band unbal to unbal transformer) with my
Hamsticks.  Works great on all bands.



From [e-mail] Thu Apr 18 15:36:24 1996
From: [e-mail] (Paul Cordingley)
Newsgroups: rec.radio.amateur.antenna
Subject: J-Pole Gain (Was Re: Tuning a copper J-Pole.)
Date: Tue, 16 Apr 1996 23:13:23 GMT
Message-ID: <4l1cqd$[e-mail]>
References: <4kt4iq$[e-mail]> <[e-mail]>


Hello John, and others,

>IMHO, the j-pole is a good home-brew antenna with good performance
>and it doesn't cost much to build.

I have also found the J-pole to work really well. However,  I was
surprised recently to hear a pretty knowledgeable local ham remark
that the j-pole actually has a pretty poor gain performance.

Can anyone direct me to a good reference document on the measured
performance of the J-pole? Is there any truth to what I was told?

73
Paul
VA3MLW





From [e-mail] Thu Apr 18 15:36:25 1996
From: [e-mail] (Jim Moore)
Newsgroups: rec.radio.amateur.antenna
Subject: Re(2): Best Antenna Design Program?
Date: Sun, 14 Apr 96 21:19:08 -0800
Message-ID: <[e-mail]>

I would like to find a source for the freeware, NEC2 as mentioned
in following copy of a message:

Tom ([e-mail]) wrote:

     Thomas Mahanna ([e-mail]) wrote:

:       What's the best Antenna Design Program for DOS/WIN/OS2?

    Best??  Depends on what you want to do!  First, I'd characterize
    them more as _analysis_ than design programs, for the most part.
    Perhaps Antenna Optimizer and Yagi Optimizer qualify as "design"
    programs, but you have to give them a starting point and specify
    what you want to optimize, if I'm not mistaken.

    I use EZNEC from Roy Lewallen, and I find it generally easy to use
    and pretty reliable.  It's a DOS program.  There is a Windows
    program that's also based on NEC2 code (like EZNEC is) that
    seems (from the demo version) to have capabilities very similar
    to EZNEC...maybe someone else can review it and give the vendor's
    name.

    You can get NEC2 code as freeware, I believe, but then you will be
    stuck doing your own input formatting and interpretation of the
    tabular output; the others have much simplified inputting and
    graphical output.  One advantage is you have access to all the NEC2
    features--I believe you can do planes and cylinders in NEC2 that the
    other programs don't give you access to...maybe someone else knows
    otherwise and can correct me if this is wrong.

    --
    Cheers,
    Tom
    [e-mail]





From [e-mail] Thu Apr 18 15:36:26 1996
From: [e-mail] (Walt Davidson)
Newsgroups: alt.radio.scanner,alt.radio.pirate,aus.radio,rec.radio.amateur.antenna,rec.radio.amateur.equipment,rec.radio.amateur.misc,rec.radio.scanner,rec.radio.shortwave,uk.radio.amateur
Subject: Re: Sxxx, my FM-25 is Fxxxxx! What to do??
Date: Sun, 14 Apr 1996 07:50:29 GMT
Message-ID: <4kqaue$[e-mail]>
References: <[e-mail]> <4ijvsq$[e-mail]> <4ikqld$[e-mail]> <4jmrld$[e-mail]> <[e-mail]> <4k0dt6$[e-mail]> <4k19av$[e-mail]> <4k3p56$[e-mail]> <4k5rmr$[e-mail]> <4kjb9v$[e-mail]> <4komm1$[e-mail]>

[e-mail] (Roger Wiseman) wrote:

>hey.., wasn't there a Bob Clary on "Hogan's Heroes????!!!" <<grin>>

Are you sure that wasn't Julian Clary?

:-))))))))

Regards,

--
Walt Davidson               E-mail: [e-mail]
                                    [e-mail]




From [e-mail] Thu Apr 18 15:36:28 1996
From: [e-mail] (W8JI  Tom)
Newsgroups: rec.radio.amateur.antenna
Subject: Re: The Transmitter Chassis
Date: 17 Apr 1996 05:28:57 -0400
Message-ID: <4l2dkp$[e-mail]>
References: <4kv9lt$[e-mail]>

In article <[e-mail]>, [e-mail] (Alfred Lee)
writes:

>>
>> Yes, at *audio* frequencies, where *skin effect* doesn't come into
>> play, this is true. But at RF, where skin effect does come strongly
>> into play, the signal on the *inside* of the connector shell can't
>> get to the outside of the connector shell, or the outside of the
>> chassis. The thickness of those parts is several skin depths, so
>> their insides and outsides are isolated from each other.

The insides and outsides are only isolated if there is a equal and
opposite current involved. Without equal and opposite currents, even VHF
current can flow right through a chassis to the outside. All shields
depend on this effect.

Inside and outside are bad terms to use. I like the surface and interior
better! While current doesn't flow through the interior, the voltage is
the same on each side of the wall. And the outside is a continious path in
a three dimensional world. The only thing that keeps the current inside a
coaxial cable is the equal and opposite currents, the skin depth "allows"
it to happen.

>With so much talk about skin effect every where I have never seen
>a figure being quoted.  I firmly believe some figures will put
>discussions and understandings in perspective.  So here it goes:
>
>    THE SKIN DEPTH AT 100 MHZ IS 0.66 uM (MICRON)
>
>The variations due to different material is within an order of
>magnitude.  If my memory failed me please quote the correct figure.
>I think the number is so incredible that everyone should know.

But current continues for some depth beyond that point. And don't try to
treat the conductor interior as insulation, it doesn't always work.

>On some previous posts RF current within the coaxial transmission line
>and outside the shield were discussed.  The discussion centered on the
>effect of line length, particularly at 1/4 wave length and 1/2 wave
>length.  Doesn't the difference in velocity factors causes the current
>maximum/minimum to occur at different location?  For RF current within
>the coaxial line the V.F. is 66% (or some other number.)  For RF
>current on the outside shield, due to the skin effect, the entire
>cable might just as well as a solid conductor, for which the V.F.
>is around 95%.  Wouldn't this effect make any difference?

While we know what the inside TEM mode VF is, we usually don't know what
the outside (common mode) VF is!  It depends on the cable's surrounding
environment.

73 Tom


From [e-mail] Thu Apr 18 15:36:28 1996
From: Tim Saffa <[e-mail]>
Newsgroups: rec.radio.amateur.antenna
Subject: Re: Tuning a copper J-Pole.
Date: 16 Apr 1996 00:53:47 GMT
Message-ID: <4kur2s$[e-mail]>
References: <4kt4iq$[e-mail]>
To: [e-mail]

I build j-poles all the time and have very little trouble tuneing them

what are the measurements you are useing I use 58 1/2 on the long side and 19
1/2

on the stub useing  1/2 copper put a 1 1/4 in space between the two legs put t
he

center conductor on the stub and sheild on the long leg start with your clamps
 about

2 in. up from the j they usally tune about 1 to 1 across the band be sure to p
ut a

insulator at the top of the j to keep the gap the same in high wind , if it mo
ves in

the wind it will cause the swr to go up and down


                               good luck 73's Tim KB5SSQ




From [e-mail] Tue Apr 23 07:41:51 1996
Newsgroups: rec.radio.amateur.antenna
From: "Robert W. Lewis" <[e-mail]>
Subject: Re: "VISALIA MOBILE ANTENNA SHOOTOUT"
Message-ID: <[e-mail]>
Date: Fri, 19 Apr 1996 21:34:41 -0400
References: <4ko5eo$[e-mail]>

Jesse Touhey wrote:
>
> Reminder: Next Saturday (April 20th) W6KKT will be conducting another
> 75 meter mobile antenna system field strength trial. Testing will start
> around 9:00am, test freq:3995kc,max antenna height:13.5'tip to ground.
> The location will at the U.S.Towers factory, Visalia Calif. So, If you
> will be attending the Visalia DX convention or in the area April 20th
> come join us and see how your 75 meter mobile antenna system compares
> with some of the best in the country....73s...Jesse (W6KKT)

How about some tests on other bands.  I know 75 is kind of a worst-case.
I'd think Ham Stick and some of the other "less conspicuous" antennas
arn't so bad at higher bands (maybe a good compromise).



From [e-mail] Tue Apr 23 07:41:52 1996
From: [e-mail] (CHARLES J. MICHAELS)
Newsgroups: rec.radio.amateur.antenna
Subject: Re: 1. Need Help With RFI Problems
Date: 17 Apr 1996 19:02:17 GMT
Message-ID: <4l3f7p$[e-mail]>


Mike said -

My and my neighbors Stereo equipment and her sound system on her computer
are the biggest problems

My stereo has signals that are loud.  I tried putting LC filters in the speake
r
leads, no dice, disconnected them and still have loud signals.  My theory is
it is the line (110v).  When I raise the volume, the interference gets a bit l
ow
er and
audio comes in over the interference, but the interference does not increase i
n

volume with the volume control with headphones only hooked up to stereo.
My Computers sound system also has noise.


Mike,
        This is usually due to rectification of yur RF in the output
transistors of the amplifier driving the speakers.  If so you must
put the filters at the amplifier output to the speaker lines.  A few
turns around an appropriate toroid and a SMALL bypass capacitor to
ground on the amplifier side.  If you use too much capacitance some
amplofiers become unstable and oscillate.

Charlie W7XC
--


From [e-mail] Tue Apr 23 07:41:54 1996
From: [e-mail] (W8JI  Tom)
Newsgroups: rec.radio.amateur.antenna
Subject: Re: 80 Meter Helix
Date: 18 Apr 1996 11:20:57 -0400
Message-ID: <4l5mkp$[e-mail]>
References: <4l3k9s$[e-mail]>

In article <4l3k9s$[e-mail]>, [e-mail] (Bill
Brannick) writes:

>So.. was considering other possibilities... does anyone have any
>design specs and anticipated performance comments on a vertical
>helix...for 80 meters... I was think about winding abt 200 feet of
>close spaced wire on a piece of 2-3/8" PVC and come off the the top of
>it with another 70 feet or so as a sloper...
>
>The highest I can goes with anything is about 35 feet.
>
>Not sure what I should feed this thing with, either...
>
>Any thoughts would be appreciated....
>
>Afterthought.. wonder if it might work on 160 also... then again..
>maybe it wont work on 80 either...
>
>Just gropping around for ideas here...
>
>Bill....KN6FJ

Hi Bill,

As a general rule, winding a lot of wire (or zig zagging it back and
forth) does nothing to help the antenna, and actually can hurt its
performance.

You'd be much better off to use a simple inverted L with a 30 foot or so
vertical section and a 30 foot flat top loading wire, or a liumped top
loading setup at the top.

You'll need a good ground system with as any radials as you can install
also.

I have a top loaded 35 foot vertical on 80, with 60 or 80 1/4 wl long
radials. That small vertical ties my dipole ( and the dipole is 135 feet
high ) into Europe.

73 Tom


From [e-mail] Tue Apr 23 07:41:55 1996
From: [e-mail] (WB3U)
Newsgroups: rec.radio.amateur.antenna
Subject: Re: 80 Meter Helix
Date: Fri, 19 Apr 96 04:30:19 GMT
Message-ID: <4l7cg2$[e-mail]>
References: <4l3k9s$[e-mail]>

   [e-mail] (Bill Brannick) wrote:

>Not happy with the performance of my 138 ft dipole (center-fed with
>450 ohm open wire to a tuner). Does OK out to abt 750 miles or so..
>but thats abt it.. I can hear a lot father then that but I cant get
>to them, even with a little power.  Primary short coming, I suspect,
>is the height of the dipole .. only abt 28-30 feet and I do not have
>a way to get it any higher.

My dipole is not too different from yours, just a little longer (about
200').  Assuming I wanted a DX antenna and didn't mind the increased
noise, my choice would be a shortened vertical.  A 30' vertical with a
single-band matching network at the base can be very efficient on this
band.  The trick is to keep losses in the network low and to use
plenty of full-size radials.

Unfortunately, a shortened antenna of this type will have a narrow
bandwidth.  For best efficiency, you will either need to use it only
on a relatively narrow segment of the band, or use a remotely-tuned
matching network.

73,
Jack  WB3U


From [e-mail] Tue Apr 23 07:41:56 1996
Newsgroups: rec.radio.amateur.antenna
From: Ron Lile <[e-mail]>
Subject: Re: 80 Meter Helix
Message-ID: <[e-mail]>
References:  <4l3k9s$[e-mail]>
Date: Sat, 20 Apr 1996 03:53:20 GMT

[e-mail] (Bill Brannick) wrote:
>
> Not happy with the performance of my 138 ft dipole (center-fed with
>SNIP
  Primary short coming, I suspect, is
> the height of the dipole .. only abt 28-30 feet and I do not have a
> way to get it any higher.
>
> So.. was considering other possibilities... does anyone have any
> design specs and anticipated performance comments on a vertical
> helix...for 80 meters... I was think about winding abt 200 feet of
> close spaced wire on a piece of 2-3/8" PVC and come off the the top of
> it with another 70 feet or so as a sloper...
>
> SNIP

> Any thoughts would be appreciated....
>
> Afterthought.. wonder if it might work on 160 also... then again..
> maybe it wont work on 80 either...
>
> Just gropping around for ideas here...
>
> Bill....KN6FJ
>
Hiya Bill - Just a few comments about a helix
1) The helix makes a dandy shortened vertical and radiates just like a
vertical (broadside to axis) when the diameter is a small fraction of a wave
length - the 2 3/8" qualifies.

2) As a result of the small diameter, the bandwidth will be on the same order
as a vertical piece of pipe or tubing of the same size.

3) Due to the wire resistive losses it will have more loss and therefore lower

efficiency than a full 1/4 wave vertical or your dipole. Is this measureable?
Proably not, but Za will be higher than pure calculation for feed impedance.

4) It can be very much shorter than a full 1/4 wavevertical - reason that
helix wound verticals are used in many portable operations. It will
be much easier to transport and install.

5) The feedpoint can be calculated, but for most windings ranges it can vary
quite abit. Very noncommital here because last vertical helix I built was for
40 and was 15 feet vs 33 feet for 1/4 wave vertical and did not work as well.

6) 40 meter version did not work as well - I believe that the ground requireme
nts
are more critical as the current consentrations are closer in (?) and with the

short length, surrounding objects have more effect.

You did not mention bandwidth requirements, so with the above comments
in mind and not knowing the lay of your land, I would tend to stick to a plane
old vertical as tall as I can get with top hat loading or several wires off
the top. Feed RF to it with a tuner and have fun.

Ron K0RL


From [e-mail] Tue Apr 23 07:41:58 1996
From: "Tom C. Brown, Jr." <[e-mail]>
Newsgroups: rec.radio.amateur.antenna
Subject: Re: 80 Meter Helix
Date: Sat, 20 Apr 1996 16:41:25 -0500
Message-ID: <[e-mail]>
References: <4l3k9s$[e-mail]> <4l5mkp$[e-mail]>

> I have a top loaded 35 foot vertical on 80, with 60 or 80 1/4 wl long
> radials. That small vertical ties my dipole ( and the dipole is 135 feet
> high ) into Europe.
>
> 73 Tom


GREAT information!  I've been wanting to hear a comparison like that for
a LONG time.  Now, I can go ahead with my plans for an antenna similar
to yours.  Had the pole for a long time, but have been putting it off,
while vascilating over whether I oughta persue the vertical or a higher
horizontal antenna.  You made my mind up for me with your comparison.

Right now, I use an end-fed inverted V that is about 200 feet long, with
the apex at about 50' for both 80 and 160 and I have been very pleased
with the results.  But I've been wanting to play with a ground mounted
vertical for a long time.  Used to be a broadcast engineer and I really
enjoy that sort of stuff.  Wish I had the real estate for a really nice
phased array of ground mounted verticals for 80 and 160.

Thanks for the info, Tom!

73, Tom KJ5IE


From [e-mail] Tue Apr 23 07:41:59 1996
From: William Nolle <[e-mail]>
Newsgroups: rec.radio.amateur.antenna
Subject: Antenna Hardware
Date: Mon, 22 Apr 1996 04:13:05 -0700
Message-ID: <[e-mail]>

I'm new to this group and find it very interesting, lot's of good
information. My question is that i find it hard to find the right
hardware to build a yagi. I have build several 2 meter yagi's from 3 to 6
element but always have problems finding the right hardware like stainles
steel U bolts etc. Right now i'm in the process of designing (Using
computer software) an 16 Element ATV yagi but am in need of some element
insulators and SS pushnuts.  I know there are a couple of places listed
in the back of the ARRL handbook but with no address or phone number.
If you have such info would you please share it with me. Thanks in
advance. I would appreciate sending it to my e-mail address since i'm not
sure i'm doing this newsgroup thing right Hi.


From [e-mail] Tue Apr 23 07:42:01 1996
From: [e-mail] (Gary Hosler - KN0Z)
Newsgroups: rec.radio.amateur.antenna
Subject: Re: Antenna Modeling Software
Date: Fri, 19 Apr 1996 13:16:42 GMT
Message-ID: <4l83rg$[e-mail]>
References: <4kvfhr$[e-mail]> <4l34ll$[e-mail]>

[e-mail] (Tom Bruhns) wrote:

>Roy Lewallen ([e-mail]) wrote:
>: In article <4ktf7o$[e-mail]>,
>:    [e-mail] (Robert G. Strickland) wrote:

>: >This is true. However, after much struggle and online time, I have
>: >determined that one cannot print the plots under W95. You/I have to
>: >run the program from the C:\ prompt; that is, quit W95 and restart the
>: >computer in DOS mode. Then, printing works okay. BTW, this is also
>: >true of Miniprop, another DOS program. I am not well versed enough to
>: >explain the reasons behind this, but it seems to be the case. Roy, you
>: >might want to look into this. Otherwise, I agree with others: EZNEC is
>: >a fine program that is entertaining, helpful, instructive and easy to
>: >use.

>: I would appreciate very much hearing from anyone who has been unsuccessful
>: -- or successful -- in printing EZNEC plots under Windows 95. I certainly
>: will look into this. Please send the info to me at [e-mail].

>No trouble printing graphics or text from EZNEC here on a Pentium/W95
>system to a LaserJet IIP set as the default printer.

>--
>Cheers,
>Tom
>[e-mail]

Works just fine using a Pentium and Windows NT to a Laerjet Series II
and a Laserjet IIIP.

Opinions expressed herein are my own and may not represent those of my employe
r.


From [e-mail] Tue Apr 23 07:42:01 1996
From: Ted F <[e-mail]>
Newsgroups: rec.radio.amateur.antenna
Subject: Re: Antenna Modeling Software
Date: Fri, 19 Apr 1996 10:31:16 -0400
Message-ID: <[e-mail]>
References: <4kvfhr$[e-mail]> <4l34ll$[e-mail]> <4l83rg$[e-mail]>

DGary Hosler - KN0Z wrote:
>
> [e-mail] (Tom Bruhns) wrote:
>
> >Roy Lewallen ([e-mail]) wrote:
> >: In article <4ktf7o$[e-mail]>,
> >:    [e-mail] (Robert G. Strickland) wrote:
>
> >: >This is true. However, after much struggle and online time, I have
> >: >determined that one cannot print the plots under W95. You/I have to
> >: >run the program from the C:\ prompt; that is, quit W95 and restart the
> >: >computer in DOS mode. Then, printing works okay. BTW, this is also
> >: >true of Miniprop, another DOS program. I am not well versed enough to
> >: >explain the reasons behind this, but it seems to be the case. Roy, you
> >: >might want to look into this. Otherwise, I agree with others: EZNEC is
> >: >a fine program that is entertaining, helpful, instructive and easy to
> >: >use.
>
> >: I would appreciate very much hearing from anyone who has been unsuccessfu
l
> >: -- or successful -- in printing EZNEC plots under Windows 95. I certainly
> >: will look into this. Please send the info to me at [e-mail].
>
> >No trouble printing graphics or text from EZNEC here on a Pentium/W95
> >system to a LaserJet IIP set as the default printer.
>
> >--
> >Cheers,
> >Tom
> >[e-mail]
>
> Works just fine using a Pentium and Windows NT to a Laerjet Series II
> and a Laserjet IIIP.
>
> Opinions expressed herein are my own and may not represent those of my emplo
yer.

Do you know of any shareware modeling software for win95 or dos that I can FTP
 from the
net.  I've tried looking myself but all I find is stuff written in basic and t
he like.
Ted F.


From [e-mail] Tue Apr 23 07:42:03 1996
From: Cecil Moore <[e-mail]>
Newsgroups: rec.radio.amateur.antenna
Subject: Re: Antenna Modeling Sof
Date: 18 Apr 1996 15:14:49 GMT
Message-ID: <4l5m99$[e-mail]>
References: <4kprm9$[e-mail]> <[e-mail]> <4l0ph1$[e-mail]>

[e-mail] (Jim Fellows) wrote:
>
>OS/2?  What's that? =8~}

Hi Jim, isn't that an old obsolete operating system like CPM? :-)

73, Cecil, KG7BK, OOTC  (not speaking for my employer)




From [e-mail] Tue Apr 23 07:42:04 1996
From: Bill Meara <[e-mail]>
Newsgroups: rec.radio.amateur.antenna
Subject: Antenna Theory Question
Date: 19 Apr 1996 00:53:30 GMT
Message-ID: <4l6o6a$[e-mail]>

I'm studying the theory behind Electromagnetic Radiation. I'm using Ken
Macleish, W7TX's excellent "Why an Antenna Radiates"  from the November
1992 QST. Here is my question:

Examining the fields that arise as a result of the RF energy being
delivered to the antenna (half wave dipole) by the transmission line,  I
see that we get a changing magnetic field that arises from the current
(maximum at the center) and a changing electric field that arises from
the voltage (maximum on the ends and 90 degrees out of phase with the
current).  The antenna is like a big LC resonant circuit with energy
being exchanged between potential and kinetic, electric and magnetic.
So far so good.    Now,  Ken describes how the RADIATION FIELD is simply
the combination of the Magnetic field and the  (in phase) electric field
that arises from the electron acceleration.  Makes sense to me:  Changing
magnetic field generates changing electric field and off we go!  Soon we
are chasing DX!

But why do we specify that the Radiation originates in the antenna's
_magnetic field_ and not in the electric field that is building, rising
and falling between the ends of the dipole?  There you have a fluctuating
Electric field 90 degrees out of phase with the magnetic field that was
produced by the current.  Ken seems (like most authors on this subject)
to dismiss this "other" field as the "inductive" or "near" field.  But
shouldn't this field ALSO be a source of EM radiation?   Shouldn't we
have a second EM wave 90 degrees out of phase with the first?

Let me put it another way:  Consider the ends of the antenna to be the
plates of a big capacitor.  This cap is being charged and discharged at
radio frequencies.  Shouldn't this too be generating a magnetic around
the fluctuating electric field lines.... and RF EM energy?

Equal Rights For E fields!!!!!  (???)


Help!   73    Bill   N2CQR/HI8



From [e-mail] Tue Apr 23 07:42:06 1996
From: [e-mail] (W8JI  Tom)
Newsgroups: rec.radio.amateur.antenna
Subject: Re: Antenna Theory Question
Date: 19 Apr 1996 08:28:27 -0400
Message-ID: <4l80tb$[e-mail]>
References: <4l6o6a$[e-mail]>

Hi Bill,
In article <4l6o6a$[e-mail]>, Bill Meara
<[e-mail]> writes:
>
>But why do we specify that the Radiation originates in the antenna's
>_magnetic field_ and not in the electric field that is building, rising
>and falling between the ends of the dipole?

I haven't read that article, but I assume it prepares you by explaining
the shape and reduction in intesity of the various fields as distance is
increased.

While both descriptions of fields exist near any practical EM radiator, we
have to remember that it's the acceleration of charges that produces
effects we "describe" as the EM field. Changing potential, by itself, can
not do that. With no "wiggling" electrons we have no EM fields.

The effect we are interested in are the EM field effects, and since they
are tied directly to how many electrons are accelerated (wiggling
electrons) over how much area. Fields directly related to the
acclelerating electron effect are the only ones that allow a good
description, and potential does not indicate how many charges we
accelerated ove what difference.

>There you have a fluctuating
>Electric field 90 degrees out of phase with the magnetic field that was
>produced by the current.  Ken seems (like most authors on this subject)
>to dismiss this "other" field as the "inductive" or "near" field.  But
>shouldn't this field ALSO be a source of EM radiation?   Shouldn't we
>have a second EM wave 90 degrees out of phase with the first?
>
>Let me put it another way:  Consider the ends of the antenna to be the
>plates of a big capacitor.  This cap is being charged and discharged at
>radio frequencies.  Shouldn't this too be generating a magnetic around
>the fluctuating electric field lines.... and RF EM energy?

Displacement currents are imaginary currents. The current in the
conductors of the  capacitor will radiate EM "waves", but not the area
between the plates. No electrons move in that area,  just "imaginary"
electrons we call displacement currents so the circuit theorists don't
"flip out".

>Equal Rights For E fields!!!!!  (???)

All fields are not created equal. We should enjoy the differences, and
accept them as part of life.

73 Tom



From [e-mail] Tue Apr 23 07:42:08 1996
From: [e-mail] (Tom Bruhns)
Newsgroups: rec.radio.amateur.antenna
Subject: Re: Antenna Theory Question
Date: 22 Apr 1996 16:02:37 GMT
Message-ID: <4lgait$[e-mail]>
References: <4ld726$[e-mail]>

Bill Meara ([e-mail]) wrote:

: Suppose you could build a big capacitor with lots of space between the
: plates.  Put a lot of RF across the plates and completely shield the
: leads so that no RF is transmitted from the field lines.  Would we get EM

How would you propose to do that?  You must realize that a metallic shield
works only because there is a current in it which cancels (some part of the
effect of) the radiation it's shielding.  That is, if you have no current
in a shield, it isn't a shield.  OK, how are you going to feed current to
your capacitor and have an equal but opposite polarity current in the
shield, unless the shield also encompasses the capacitor itself?

: waves ?  Would the "displacement currents"  (whatever they are!) fill the
: void (pun intended!) left by the currents that would have flowed in the
: antenna's wire? This would really be a "Wireless" antenna  :-)

Perhaps if you could build it, but I don't see how you can...

One experiment you can think of is to charge a capacitor, then physically
move the plates apart and together sinusoidally.  The electric field in
the capacitor changes, but...you also have a current in space, in that you
are moving the charge that's on a plate back and forth along with the
plate.

How can you get a changing electric field with no change in the
distribution of charge??    I think if you find a way, it will be akin
to a perpetual motion machine...


--
Cheers,
Tom
[e-mail]


From [e-mail] Tue Apr 23 07:42:10 1996
From: [e-mail] (W8JI  Tom)
Newsgroups: rec.radio.amateur.antenna
Subject: Re: Antenna Theory Question
Date: 22 Apr 1996 12:20:30 -0400
Message-ID: <4lgbke$[e-mail]>
References: <4ld726$[e-mail]>

In a message dated 96-04-21 06:43:04 EDT, you write:

>That said, isn't it true that EM theory predicts that the changing E
>field between a capacitor's plates will generate a changing M field
>around those flux lines?  I have a pretty good text book that actually
>has a picture of this happening.  As I understand it, Maxwell devised the

>concept of "displacement current" in space in order to keep the theory
>consistent with the idea that magnetic fields stem from currents.
>
>Suppose you could build a big capacitor with lots of space between the
>plates.  Put a lot of RF across the plates and completely shield the
>leads so that no RF is transmitted from the field lines.  Would we get EM

>waves ?  Would the "displacement currents"  (whatever they are!) fill the

>void (pun intended!) left by the currents that would have flowed in the
>antenna's wire? This would really be a "Wireless" antenna  :-)

You know you've poised an interesting question, one that was no my
understanding of how the system worked.

None of my textbooks have anthing relating to the example and reasoning
that displacement currents would produce EM waves. What book were you
referring to that paint's that picture??

Anyway, since it's impossible to "shield" the leads going to the capacitor
without shielding the entire capacitor, we can never know the answer to
your question except by theory, hi.

I'll look into that more and if I find anything out I'll let you know.

73 Tom


From [e-mail] Tue Apr 23 07:42:11 1996
From: [e-mail] (W8JI  Tom)
Newsgroups: rec.radio.amateur.antenna
Subject: Re: Antenna Theory Question
Date: 22 Apr 1996 13:27:26 -0400
Message-ID: <4lgfhu$[e-mail]>
References: <4lgait$[e-mail]>

In article <4lgait$[e-mail]>, [e-mail] (Tom Bruhns)
writes:

>
>How would you propose to do that?  You must realize that a metallic
shield
>works only because there is a current in it which cancels (some part of
the
>effect of) the radiation it's shielding.  That is, if you have no current
>in a shield, it isn't a shield.  OK, how are you going to feed current to
>your capacitor and have an equal but opposite polarity current in the
>shield, unless the shield also encompasses the capacitor itself?

Hi Tom,

We certainly agree on that point, which raises another question.

How can we "shield" a loop antenna? I've been trying for years and have
been totally unsucessful. Every time I get the E field to go to zero, so
does the H field.

Maybe the mirror of the scheme used to "shield a loop for E fields" can be
used to "shield a capacitor for H fields".

Think about that the next time you read about using a shielded a loop to
improve reception!

73 Tom


From [e-mail] Tue Apr 23 07:42:11 1996
Newsgroups: rec.radio.amateur.antenna
From: [e-mail] (Dennis Mobley)
Subject: Auto Tuner vs Multiband Vertical
Date: Mon, 22 Apr 1996 15:44:58 GMT
Message-ID: <[e-mail]>

What would work better & why:
        1. An auto tuner such as a SGC or ICOM connected to the end
           of a 50 foot horizontal wire 20 feet high.
        2. A multi band vertical such as a Cushcraft R7000 or Gap Titan.
Goals:
        1. 10 thru 40 meter coverage. (80m would be a plus)
        2. Max 100 watts transmitter.
        3. No ground radials do to other restrictions.
        4. Some what stealth. Limited wires to 50 feet and
           verticals are OK. Fifty foot towers are not.
Other information:
        1. Urban city lots.
        2. Terrain is very flat.

We are looking for inputs from others as to any experience
in low impact, multiband antennas.

Thank you,
Dennis Mobley KT4FI
Sunrise, Fl.


From [e-mail] Tue Apr 23 07:42:12 1996
From: [e-mail]
Newsgroups: rec.radio.amateur.antenna
Subject: BCB-DXing
Date: Sat, 20 Apr 96 10:35:45 PDT
Message-ID: <[e-mail]>


I'm posting my question here, because it sounds like this is where the experts

are.
I am a broadcast band DX-er.
I get the best results using a ( digital display ) auto radio, with a bench
power supply.
I realize that these radios are "tuned" to match a (30") whip antenna.
I'd like to experiment with long wire, and home-brew loop antennas.
Is there a simple circuit that will allow me to "match" them to the
car radio input? ( I think the mystery of impedence is beyond me )
My electronic expertise is "beginner", my parts sources, Radio Shack.
( I can wind a coil, solder a wire )
Any help would be appreciated.





From [e-mail] Tue Apr 23 07:42:13 1996
From: [e-mail] (ken.thompson)
Newsgroups: rec.radio.amateur.antenna
Subject: Re: Beam Antenna for 27Mhz
Date: Mon, 22 Apr 1996 13:14:05
Message-ID: <[e-mail]>
References: <4l4953$[e-mail]>

In article <4l4953$[e-mail]> [e-mail] writes:
>From: [e-mail]
>Subject: Beam Antenna for 27Mhz
>Date: 18 Apr 1996 02:24:35 GMT

>Does anyone have any info on how to build a beam for a 27Mhz mobile? I
>would like to try this as an experiment instead of getting an illegal
>linear. Any help would be appreciated such as length and spacing and gain
>and even coax length.

>Thanks,

HMMM.
1/2 elements on a yagi for 11m.  about 16 feet tall.
2-3 wavelength beam (6-? ele)     about 66 feet long.

I think it will require an OVERSIZED load permit.



From [e-mail] Tue Apr 23 07:42:14 1996
From: [e-mail] (Roy Lewallen)
Newsgroups: rec.radio.amateur.antenna
Subject: Re: Best mobil antenna program?
Date: Thu, 18 Apr 96 20:33:32 GMT
Message-ID: <4l68ss$[e-mail]>
References: <4l2mtr$[e-mail]>

In article <4l2mtr$[e-mail]>, (Gary) (KF9CM) [e-mail] wrote:
>I have tried an older Elnec program for modeling mobil antennas and it
treets the
>inductor as a lumped inductance.  This does not take into account the "Q"
of the
>coil.  Is there a program that takes in the special considerations of
mobil antennas
>or shortened antennas?

The Q is handled in ELNEC and other modeling programs by including a
resistance in series with the inductor. The value of the resistance is X/Q
where X is the inductor's reactance.

Roy Lewallen, W7EL


From [e-mail] Tue Apr 23 07:42:15 1996
From: [e-mail] (James E. Bromley)
Newsgroups: rec.radio.amateur.antenna
Subject: Re: Best mobil antenna program?
Date: 18 Apr 1996 15:36:01 -0700
Message-ID: <[e-mail]>
References: <4l2mtr$[e-mail]>

In article <4l2mtr$[e-mail]>
 (Gary) (KF9CM) [e-mail] writes:

>I have tried an older Elnec program for modeling mobil antennas
>and it treets the inductor as a lumped inductance.  This does
>not take into account the "Q" of the coil.  Is there a program
>that takes in the special considerations of mobil antennas or
>shortened antennas?

I don't know about *old* versions of ELNEC, but the newer one
I use allows you to add an R in series with the inductance,
thus modeling "Q".

Jim Bromley, W5GYJ
Glendale, AZ




From [e-mail] Tue Apr 23 07:42:16 1996
From: [e-mail] (robert bowman)
Newsgroups: rec.radio.amateur.antenna
Subject: Re: Bird Strikes
Date: 21 Apr 1996 02:29:42 GMT
Message-ID: <4lc6im$[e-mail]>
References: <4l44j8$[e-mail]>

In article <4l44j8$[e-mail]>, [e-mail] (John N0ISL)
says:
>
>The latest "hazard" to the enviornmet from hams is the potential injury to
>endangered birds and other flying critters as they fly unknowingly into
>towers or tower guy wires.


the Ajo Amateur Radio Club (Ajo, AZ) had an article by a member who
interacted with a Great Horned Owl while using a HamStick for mobile
trolling. Since this occurred in the Organ Pipe National Monument, it
was probably a federal offence.


From [e-mail] Tue Apr 23 07:42:16 1996
From: [e-mail] (Jean-Guy Moreau)
Newsgroups: rec.radio.amateur.antenna
Subject: DDRR
Date: 21 Apr 96 15:37:20 GMT
Message-ID: <v01530500ad9f0028248e@[205.205.27.154]>

Where can I get information on Boyer's DDRR antenna?

Thanks,

Jean-Guy




From [e-mail] Tue Apr 23 07:42:17 1996
From: [e-mail] (Graham Seale)
Newsgroups: rec.radio.amateur.antenna
Subject: Re: DDRR
Date: Mon, 22 Apr 1996 09:02:28 GMT
Distribution: world
Message-ID: <[e-mail]>
References: <v01530500ad9f0028248e@[205.205.27.154]>
Reply-To: [e-mail]

In message <v01530500ad9f0028248e@[205.205.27.154]> Jean-Guy Moreau wrote:

> Where can I get information on Boyer's DDRR antenna?

Hi Jean-Guy

The DDRR is a short (about 1 foot) vertical with a horizontal (flat
top) circular extension with a high voltage variable capacitor at the
end going to the ground plane to provide quarter wave resonance. The
ground plane is constructed of chicken wire, and the structure looks
like a fat section hula hoop stood off the ground on plastic drainpipe
supports. It has featured in some past issues of ARRL handbook.

Back in 1991  in "The Antenna Experimenter's Guide" Peter Dodd G3LDO
published a startingly detailed mathematical modelling of the DDRR
as an illustration of the thoroughness necessary in setting up a
meaningful analysis. The study was by Robert B. Dome W2WAM who held
115 patents in transmitter and related technology at the time.

The 40m DDRR did not come out well, and the model accurately predicted
a *huge* increase in efficiency simply by increasing the vertical part
from 1 foot to 3.5 feet. (2.75 percent up to 25.8 percent - a 9.8dB
increase in signal strength!)

The efficiency is low because the radiation resistance is low (0.095 ohm)
so the conductor ohmic losses consume most of the available power.
The bandwidth is very narrow, hence the need for a motorised capacitor
to bring the system to something like unity power factor. It is compact,
low profile and inconspicuous in installation - advantages you may
consider worthwhile. It also comes with a minor mytholgy about matching
quarter-wave vertical performance - to be disregarded.

Hope this helps..

73's G4WNT

--
Graham Seale


From [e-mail] Tue Apr 23 07:42:18 1996
From: [e-mail]
Newsgroups: rec.radio.amateur.antenna
Subject: RE:DDRR
Date: 22 Apr 96 04:00:14 GMT
Message-ID: <[e-mail]>

Jean-Guy Moreau([e-mail]) asked for some info on DDRR antenna:
I found this radiator at the ARRL Antenna Handbook, thirteenth ed.
(1974), pages 214...216. The same book shows some references, below:
ELECTRONICS,  January 1963
QST, July 1972
QST, December 1972
Good luck. Marcus Ramos - [e-mail]


From [e-mail] Tue Apr 23 07:42:20 1996
Newsgroups: rec.radio.amateur.antenna,rec.radio.amateur.misc
From: [e-mail] (Gary Coffman)
Subject: Re: Different(ial) RFI Problem: partial solution
Message-ID: <[e-mail]>
Reply-To: [e-mail] (Gary Coffman)
References: <4kpd74$q2o$[e-mail]> <4kquoh$[e-mail]> <[e-mail]> <[e-mail]> <[e-mail]>
Date: Thu, 18 Apr 1996 15:35:05 GMT

In article <[e-mail]> [e-mail] (Pete Soper) writes:
>[e-mail] (Gary Coffman) writes:
>
>>Sounds like a parasitic oscillation in the stereo audio PA. Try putting
>>a resistor across the coil (start with 1k and work down) and see if that
>>stops the distortion.
>
>Thanks for the feedback, Gary (no pun intended).
>
>Jack, WB3U pointed out that I had a lot more inductance than I thought.
>My Autek RF-1 said one thing, the Amidon "AL" value for the toroid I
>used said quite another. After more careful listening it turned out I
>was clipping highs out of the audio and there was still some distortion,
>even with the 5 turns on the cores. Jack speculates the distortion
>might be core saturation.

Yeah, I think he may have hit it on the head. Frankly, I was misled
by your comment that the audio sounded "harsh". I don't equate that
with high frequency rolloff, which I'd generally say sounded "muffled",
but core saturation could definitely give you that effect by generating
step harmonics.

>So this is all bad news, as it means the three pole filter isn't going
>to do the job for eliminating the RFI on 40 meters and in fact might
>not cure it on the higher bands if I adjust the cutoff to not mess up
>the audio.
>
>My strategy now is this: air core coils, 4 poles or more, find something
>that works very well with one channel, then consider ferrite with a lower
>permeability if the size of the coils is an issue. I may have to filter
>all five channels (surround sound system) and the minibox I chose looks
>like it might get very dense now! Oh, and trust the Amidon charts, not
>my Autek for inductance values (darn!). If I get distortion with air
>cores I'll try your resistor mod.

That's just a trick to dampen parasitic oscillations. If that isn't
what's happening, then it won't help. But I'd be concerned about
your minibox. It may allow a path for the RF to *bypass* your
filtering. Think about that a bit. Capacitance to and from the
box with respect to wires entering and leaving it may be bypassing
your chokes. I'd mount them out in the open, with the inductors
well separated to avoid mutual coupling.

>One additional question I raised with Jack: If this really is a differential
>mode RFI problem, is the stereo receiver's AC line likely to be providing
>a return path, and if so, should I try aggressively filtering it?
>I could put some very serious filtering in place on the AC feed before
>my violin strings sounded like power tools :-)

I'm still somewhat puzzled how you could have differential currents
on your speaker leads. Aren't they tightly paired? And didn't you
say that you still had the problem with the speaker wires disconnected
and using headphones (or was that someone else)? If you do have differential
currents, then by definition they are differential with respect to *each
other* and not to some third wire.  However, I would certainly try a
common mode choke on the AC cord. It can't hurt.

Gary
--
Gary Coffman KE4ZV          |    You make it,     | Due to provider problems
Destructive Testing Systems |    we break it.     | with previous uucp address
es
534 Shannon Way             |    Guaranteed!      | Email to [e-mail]
Lawrenceville, GA 30244     |                     |


From [e-mail] Tue Apr 23 07:42:22 1996
From: [e-mail] (WB3U)
Newsgroups: rec.radio.amateur.antenna,rec.radio.amateur.misc
Subject: Re: Different(ial) RFI Problem: partial solution
Date: Fri, 19 Apr 96 07:08:54 GMT
Message-ID: <4l7lpb$[e-mail]>
References: <4l5n93$[e-mail]> <4l6gi5$[e-mail]>

   [e-mail] (W8JI  Tom) wrote:

>Be careful here fella's. Core saturation would NOT produce noticable
>distortion. Forget about that.

Tom, the nonlinear attenuation created by a core driven into
saturation will cause plainly audible distortion. I've heard it many
times in the course of attempting to match poorly specified crossover
networks to high power drivers.  It's a well-known phenomenon.

>Since the inductance of the cores should be negligible at audio
>frequencies, and distortion caused by core saturation would also be
>negligible. The effect will be only that of adding a non-linear
>inductance in series with the audio path, of an inductance value that
>has no affect on the audio frequency signals anyway.

In the example cited, 9 or 10 turns were wound through a FT-50A-75
toroid.  From calculations, the inductance of this coil is
approximately 300 uH.  Not only is this value not negligible, it's
suitable for a 6 dB/octave upper midrange crossover at 4500 Hz.  Based
on the size of this particular core, I would expect it to create
noticeable distortion at even moderate power levels.

Incidentally, I question the negligible effect of core saturation even
when (in your words) "the inductance value has no effect on the audio
frequency signals".  The level of audio harmonics created by
saturation of an RF inductor may indeed seem insignificant when
compared to the level of audio current passing through the coil.
However, relative to the level of harmonics created by the amplifier
(which may be well below 0.05%), those created in the saturated coil
might not be so small.

>Core saturation is a moot point unless the design impedance or
>application of the inductors is far from correct, so an air core coil
>of the same impedance will produce the same results.

The application of the inductor *was* far from correct.  These
were the wrong cores for the job at hand, and in addition, too many
turns were used.  If for some reason these cores were the only choice,
only 2 or 3 turns (maximum) would be required.  That doesn't provide
much control over the resultant inductance, which is one more reason
a core using 43 or 61 material (or air) would be more appropriate.

>Look for instability in the amp caused by the load change, and lower
>the values of those .1 caps.

What load change?  Not the nonlinear inductance?  If that causes
instability in a solid-state audio amp, the amplifier is defective.
Impedance VS frequency changes in the drivers themselves are *huge*,
not to mention the impedance fluctuations introduced by the typical
crossover network.

The shunt capacitors of 0.1 uF are also unlikely to cause instability
unless something is amiss in the amplifier.  Whatever the effect of
these caps, it will not be nearly as significant as the much larger
capacitors typically used in series with the midrange and tweeter.

Again, what Pete experienced was almost certainly the result of
saturation of the toroidal cores. The solution will be the use of a
core material (and shape) more specifically suited to RF applications
and less prone to saturation.

73,
Jack  WB3U


From [e-mail] Tue Apr 23 07:42:22 1996
From: Don Wilhelm <[e-mail]>
Newsgroups: rec.radio.amateur.antenna,rec.radio.amateur.misc
Subject: Re: Different(ial) RFI Problem: partial solution
Date: 19 Apr 1996 23:46:39 GMT
Message-ID: <4l98kv$[e-mail]>
References: <4kpd74$q2o$[e-mail]> <4kquoh$[e-mail]> <[e-mail]> <4l5n93$[e-mail]>

Pete (and others),
I don't know where I heard it, and I won't vouch for it as truth, but I believ
e
that many audio amplifiers are VERY sensitive about a capacitive load.
Therefore, you audio distortion may be the result of the caps across the
speaker leads.  You might try just running about 10 turns of the speaker leads
through a toroid core.  I know this will only cure the common mode pick-up, bu
t
unless you are certain you are dealing with differential mode stuff, it is wor
th
a try.

73,
Don W3FPR





From [e-mail] Tue Apr 23 07:42:24 1996
From: [e-mail] (Steve Mason)
Newsgroups: rec.radio.amateur.antenna
Subject: Re: Ethernet Terminator at UHF
Date: Thu, 18 Apr 1996 15:55:44 GMT
Message-ID: <[e-mail]>
References: <4l3eae$[e-mail]>

On 17 Apr 1996 18:46:38 GMT, Kevin Schmidt <kschmidt> wrote:

>I have a thinwire ethernet terminator that is stamped 50 ohms, 1 watt.
>It is a more or less standard type built into a BNC plug. I wondered
>what sort of dummy load it might be, so last night
>I measured its impedance at 2-meters and 70 cm. I measured:
>
>   48 -3j ohms at 146 MHz, SWR = 1.08
>   46 -9j ohms at 435 MHz, SWR = 1.24.
>
>If I believe these numbers, it looks approximately like a 48 ohm
>resistor in parallel with a 1.5 pF capacitor. Do most ethernet
>terminators have impedances and power ratings around this, or
>am I just lucky (or unlucky)? Are there known better ethernet
>terminators in terms of higher power ratings or lower SWR at UHF?

As far as I know, the average Ethernet terminator is just a 1/4 watt resistor
(somewhere near 50 ohms, usually 47) connected to a BNC connector.
So depending on the particular resistor, and it's tolerance, you'd get varying
results. I imagine it would heat up with more than 500mw of RF.

Steve


From [e-mail] Tue Apr 23 07:42:24 1996
From: Edward Lawrence <eal>
Newsgroups: rec.radio.amateur.antenna
Subject: Re: FM Station far away
Date: 19 Apr 1996 18:11:01 GMT
Message-ID: <4l8kvl$[e-mail]>
References: <4l84m3$[e-mail]>

[e-mail] (Rick Kissell) wrote:
>Hey, "eal" what the hell are you doing?  Offering this guy some practical
>advice?  Dontcha know that r.r.a.a. is supposed to be full of theoretical
>discussions only?  :)
Hello Rick!   Thanks for the laugh!  I sat here and giggled for five  minutes!
Then I went and brought a co-worker(presently studing for his Ham licience bac
k
and showed him!  Also gave him some URL's to look at.  Good for all concerned.
Thanks again!



From [e-mail] Tue Apr 23 07:42:25 1996
From: [e-mail] (WB3U)
Newsgroups: rec.radio.amateur.antenna
Subject: Re: FM Station far away
Date: Fri, 19 Apr 96 08:24:05 GMT
Message-ID: <4l7q68$[e-mail]>
References: <[e-mail]> <4kupqk$[e-mail]> <[e-mail]>

   "William G. Graves" <[e-mail]> wrote:

>An approximate formula is to take the square root of the height in
>feet and multiply by 1.15 to yield range in nautical miles.  Do this
>for each antenna and add the result.

Just wanted to mention that for crow miles, it's:

           1.42 X sqrt(H1)  +  1.42 X sqrt(H2)

73,
Jack  WB3U


From [e-mail] Tue Apr 23 07:42:26 1996
From: [e-mail] (Tom Bruhns)
Newsgroups: rec.radio.amateur.antenna
Subject: Re: FM Station far away
Date: 18 Apr 1996 16:49:47 GMT
Message-ID: <4l5rrb$[e-mail]>
References: <[e-mail]>

William G. Graves ([e-mail]) wrote:
: Pierre Tremblay wrote:
: > Even with a tower and a powerful antenna I don't think you could receive a
: > FM station 100 miles away very well. 100 MHz only gives you line of sight
propagation
: > and without digging out any big books I say you're below the horizon....

: An approximate formula is to take the square root of the height in feet and
: multiply by 1.15 to yield range in nautical miles.  Do this for each antenna
 and
: add the result.  Lets say the transmitter has a 500 foot antenna, this gives

: 1.15 * 22.4 = 25.7 nm.  For the receiver, lets assume a 60 foot tower, this
gives
: 1.15 * 7.7 = 8.9 nm.  Sum the results and the predicted range is about 34.5
nm
: which is much less than the desired 100 miles.

I think Bill's formula is OK, but I'd add a couple thoughts:  first,
depending on atmospheric conditions and frequency, the distance can be
extended because radio waves tend to be bent toward the earth -- but the
opposite can also be true under the right (wrong?)  conditions.  Second,
my experience tells me that this is extremely conservative for
100-150MHz.  Even taking "antenna height" as elevation above sea level,
I regularly do much better than this talking with mobiles in Vancouver
BC from my QTH just N.  of Seattle; and semi-quantitative experience
from a large number of fox hunts also tells me that signals will go
quite a bit further than that "line of sight" formula would predict.

Anyway, if the listener has a way to get an antenna out in the open,
line-of-sight to the horizon (instead of into the concrete jungle),
then I'd say he has a pretty good chance of getting the station he
wants.  Then the problem may well be all the other RF he picks up,
both in-band and out.

--
Cheers,
Tom
[e-mail]


From [e-mail] Tue Apr 23 07:42:27 1996
From: [e-mail]
Newsgroups: rec.radio.amateur.antenna
Subject: Glass mount on 96 Chevy Tahoe
Date: 22 Apr 1996 18:48:11 GMT
Message-ID: <4lgk9b$[e-mail]>

Anybody know if the glass on the 96 chevy tahoe has the metal used in the
production process that will not permit the use of a glass mount antenna?
I hav not gotten a difinitive answer from Chevy yet.  Couple of cell phone
places have told me that they will only do hole mounts on those vehicles
though.  Thanks.

Al, KE6BER/1, [e-mail]



From [e-mail] Tue Apr 23 07:42:29 1996
From: Cecil Moore <[e-mail]>
Newsgroups: rec.radio.amateur.antenna
Subject: Re: Hamsick or Outbacker?
Date: 17 Apr 1996 23:49:15 GMT
Message-ID: <4l401r$[e-mail]>
References: <[e-mail]> <4k0ruv$[e-mail]> <[e-mail]> <[e-mail]> <[e-mail]>

Bob Lewis <[e-mail]> wrote:
>Steve Ellington wrote:

>>That's one thing I don't understand is why these
>> mobile antennas aren't matched to begin with. After all, the
>> advertisements don't say anything about this problem.

>I use a 2:1 UNUN (broad band unbal to unbal transformer) with my
>Hamsticks.  Works great on all bands.

Hi guys, Antennas West does say in their Hamstick advertisment
that a $12 "Auto Matcher" is needed on 40m and 75m. They imply
one needs a tuner otherwise.

73, Cecil, KG7BK, OOTC  (not speaking for my employer)




From [e-mail] Tue Apr 23 07:42:30 1996
From: [e-mail] (Rich Mulvey)
Newsgroups: rec.radio.amateur.antenna
Subject: Re: Help - Help- Could glass mount ant. blow up HT???
Date: 21 Apr 1996 16:10:41 GMT
Message-ID: <[e-mail]>
References: <4lditi$[e-mail]>
Reply-To: [e-mail]

On 21 Apr 1996 11:06:26 -0400, KE6JSS <[e-mail]> wrote:
>I just finished installing a new Larsen 2m glass mount.  Cant drill
>anywhere on the car, and the glass mount seemed to be a good fit.  The
>only place that I could mount the ant. was a factory tinted window (Ford
>Bronco - 93).  The inst. said this is a no no.  But, I checked with Ford
>and they said that is was not similar to an aftermarket type - so I
>figured lets try it.
>
>After a couple of radio checks - a good 50mi + at 1 Watt, the radio went
>dead.  Not completely, just mostly.  The radio will TX, as my scanner
>proves.  It just cant key up a repeater, nor does it display a signal
>strength (at all).  I have tried nearly all of my ant's.  Please, help me.
> The radio is under warrenty.  Did the tint cause this?  Why and how?
>Reflected/Absorbed energy.

   The reason that the instructions cautioned you against installing the
antenna on a tinted window was that the metallized films often used in
tinting radically change the impedence of the glass.  Thus, the SWR
was beyond the bounds of what the HT could handle.  ( Most HT's are
built with SWR fold-back circuits to handle this sort of problem,
since they often have to look into poorly matched loads - rubber
duckies, for example.  But that doesn't appear to have been the case,
in this instance. )

   The most likely damage that you've caused to your HT is blowing
out the finals.  That's why you can hear it on your scanner - you're
still putting out enough power from the exciter, but not enough to
hit the repeater.

   Better take those warnings a little more seriously, next time.  Ford
makes cars, not radios - asking them for advice about proper installation
is akin to asking the milkman about brain surgery.  :-)

- Rich



From [e-mail] Tue Apr 23 07:42:31 1996
From: [e-mail] (WB3U)
Newsgroups: rec.radio.amateur.antenna
Subject: Re: Help - Help- Could glass mount ant. blow up HT???
Date: Sun, 21 Apr 96 17:01:13 GMT
Message-ID: <4le18m$[e-mail]>
References: <4lditi$[e-mail]>

   [e-mail] (KE6JSS) wrote:

>After a couple of radio checks - a good 50mi + at 1 Watt, the radio
>went dead.  Not completely, just mostly.  The radio will TX, as my
>scanner proves.  It just cant key up a repeater, nor does it display
>a signal strength (at all).  I have tried nearly all of my ant's.
>Please, help me. The radio is under warrenty.  Did the tint cause
>this?  Why and how? Reflected/Absorbed energy.

What's the SWR?

73,
Jack  WB3U


From [e-mail] Tue Apr 23 07:42:32 1996
From: Cecil Moore <[e-mail]>
Newsgroups: rec.radio.amateur.antenna
Subject: Re: Help - Help- Could glass mount ant. blow up HT???
Date: 22 Apr 1996 14:48:26 GMT
Message-ID: <4lg67q$[e-mail]>
References: <4lditi$[e-mail]> <[e-mail]>

[e-mail] (Rich Mulvey) wrote:
>   The most likely damage that you've caused to your HT is blowing
>out the finals.

I had the same symptoms and it was the RX/TX switching diodes that
had given up the ghost. Final was OK.

73, Cecil, KG7BK, OOTC  (not speaking for my employer)




From [e-mail] Tue Apr 23 07:42:33 1996
From: [e-mail] (Charles Hoffman)
Newsgroups: rec.radio.amateur.antenna
Subject: Re: HELP - Rhombic for amateur bands
Date: Tue, 16 Apr 1996 19:02:49 GMT
Message-ID: <4l0ufm$[e-mail]>
References: <4km0nm$[e-mail]>
Reply-To: choffman @pelican.davlin.net

An acre is 208 feet square, just for reference.  Perhaps you and your
friend don't understand what a rhombic design antenna is, but briefly
this wire antenna requires many wavelengths to yield any directivity
(gain).  You could build one for, say two meters, on an acre, but it
would be like taking the driving wood to the putting green I would
think...why?

No, I suggest you forget about a rhombic for one acre on HF.

73 Ric K5SBU
South Texas Rhombic Society

[e-mail] (Walt Cunningham) wrote:

o--->Can anyone steer me in the right direction for
o--->info on construction of a rhombic antenna field
o--->covering the amateur bands?  I am researching
o--->this for a friend ham operator in WA state who
o--->has 1 acre available (280 ft NSx150 ft EW).
o--->Is this enough area?

o--->Email to:  [e-mail] (Walt Cunningham)
o--->or post to group, please.
o--->daw di-di-daw   di-daw di-daw-dit





From [e-mail] Tue Apr 23 07:42:34 1996
From: [e-mail] (Roy Lewallen)
Newsgroups: rec.radio.amateur.antenna
Subject: Re: HELP - Rhombic for amateur bands
Date: Wed, 17 Apr 96 06:53:39 GMT
Message-ID: <4l24fk$[e-mail]>
References: <4km0nm$[e-mail]> <[e-mail]> <4l11ot$[e-mail]>

In article <4l11ot$[e-mail]>,
   [e-mail] (Jim Garver) wrote:

>Did you consider Vee Beams, especially sloping Vee's requiring only one
>high support?  A Vee Beam is half of a Rhombic practically, and retains
>most of the advantages.  I have tried a couple of flat top Vee's up 50 ft.
>with legs about 200 feet long.  Comparison against a two element yagi up
>30 feet showed surprising improvements in both directions.  I did not
>want to terminate the ends of my Vee Beams.  Something happens that the
>simulation programs cannot define, maybe capture area?

Capture area is simply another way of stating gain*, which the simulation
programs certainly deal with. What made you think that simulation programs
won't give an accurate picture of the relative performance of a Yagi and
vee beam?

Roy Lewallen, W7EL

*For example, an infinitesimally short lossless dipole would have a capture
area only about 10% less than that of a half wavelength dipole. For many
antenna types, gain isn't directly related to physical size, so capture
area isn't either.


From [e-mail] Tue Apr 23 07:42:35 1996
From: [e-mail] (Jim Garver)
Newsgroups: rec.radio.amateur.antenna
Subject: Re: HELP - Rhombic for amateur bands
Date: 18 Apr 1996 17:34:59 GMT
Message-ID: <4l5ug3$[e-mail]>
References: <4km0nm$[e-mail]> <[e-mail]> <4l11ot$[e-mail]> <4l24fk$[e-mail]>

In article <4l24fk$[e-mail]>,
Roy Lewallen <[e-mail]> wrote:
>In article <4l11ot$[e-mail]>,
>   [e-mail] (Jim Garver) wrote:

>>... something happens that the
>>simulation programs cannot define, maybe capture area?

>Capture area is simply another way of stating gain*, which the simulation
>programs certainly deal with. What made you think that simulation programs
>won't give an accurate picture of the relative performance of a Yagi and
>vee beam?

>Roy Lewallen, W7EL


I knew that I would get in trouble over the term 'capture area'.  Okay lets
just call it near field area or something.
I believe that the many simulations I've run using MN 4.0 would be accurate
if I lived somewhere in Northern Ohio where its totally flat like the ocean
and my antennas had no nearby objects such as houses.  But I don't.
When modeling over Real Ground, it becomes rather difficult to consider
houses, trees, uneven terrain, and soil conductivity differences, all of which
I have at my station.
A small area antenna such as a yagi is more affected by nearby objects than
a large wire antenna, I suspect.

 I like to model over ground after the free space design is completed
because it greatly helps me determine takeoff angles as well as true gain.
 I've confirmed some of these elevation angles and lobes by observing
the RS series satellite signal strengths (~29.35-29.45 Mhz) as they cross
over my location.
While MN (now NEC Wires, I think) lets me model crude local ground variations,
I don't trust the results versus the trouble.  Don't know about ELNEC.

WA7LDV




--
[e-mail]                             I don't speak for Intel


From [e-mail] Tue Apr 23 07:42:36 1996
From: Bill Rhodes <[e-mail]>
Newsgroups: rec.radio.amateur.antenna
Subject: HF Antennas for RV's?
Date: 22 Apr 1996 12:36:39 GMT
Message-ID: <4lfugn$[e-mail]>

I have a 23 foot travel trailer, and would like to run HF
while camping.  I would not be operating while under motion.
Anybody got any thoughts or ideas on what works well?  I am
especially interested in ideas about schemes to lower and/or
fold over the antenna for travel.  Tnx & 73 Bill, WB2JMX,
[e-mail]




From [e-mail] Tue Apr 23 07:42:37 1996
From: [e-mail] (Martin Rask)
Newsgroups: rec.radio.amateur.antenna
Subject: Homemade 6m antennas ??
Date: 16 Apr 1996 22:35:02 GMT
Message-ID: <4l17am$[e-mail]>
Reply-To: rec.radio.amateur.antenna

Hello all..

Ißm just going to start on the 6m band.. but i need a good antenna..

So i wonder if anyone has some specifiacation on Cushcrafts A50-6 6el
or A50-5 5el beam or some other good antenna for 6m the M2 6M7 6M2WLC

or maybe some other very good antenna.. 73┤s de SM7VHS /Martin

Email: [e-mail]



From [e-mail] Tue Apr 23 07:42:40 1996
From: [e-mail]
Newsgroups: rec.radio.amateur.antenna
Subject: Re: Horizontal HF loops
Date: Mon, 22 Apr 96 16:46:45 PDT
Message-ID: <NEWTNews.4449.830217782.Postmaster@hfs08>
References: <[e-mail]>


In article <[e-mail]>, <[e-mail]
>
writes:
Monty Wilson wrote:

> A friend of mine is experimenting with horizontal HF loops.  He
> built one to resonate on 80, thinking he could use it on any multiple
> of the principal frequency.  He can, but only with an antenna tuner.
> One person he talked to on HF, and who was also using a loop, told him
> that such a loop resonates on multiples, but that as you increase the
> number of multiples you also increase the feedpoint resistance; that
> only at the principal frequency is the feedpoint impedance between
> 50 and 100 ohms.  My friend's measurements seem to corroborate this,
> as the lowest SWR on 80 was 1.5:1, then 2:1 at the 40 meter resonant
> point, and off his SWR scale on bands higher than that.  He is able
> to use an automatic tuner to work almost all bands on the loop, and
> seems to be transmitting and receiving very well on it, but the
> tuner, of course, hides important information about what it is having
> to do in order to match the antenna.  His loop is about
> 40' off the ground and is a full wave on 80m.  He has had several
> people tell him to feed it with 450 ohm ladder line, which he is now
> doing, and the performance seems to be similar to that when he was
> using coax.
>
> There is a loop article in the 4/96 issue of 73, which is what got
> the two of us started on all this loop stuff.
>
> Now it's almost time to put my own station on the air, and I wonder
> if anyone has had any experience with these loops.  Horizontally-
> oriented, I mean.  I am especially interested because the reception
> seems to be far superior to that of a dipole, even off resonant
> frequencies.
>
> If you know about this, please send email to [e-mail] with
> any comments you have.
>
> Thanks,
> --
> ..........Monty.
> [e-mail]

I have a full wave horizontal loop for 40 meters, at about 35 feet.  Coax fed.

I can tune all of 40, 20, 15, with the built-in tuner of my Kenwood 450.  This

tuner can only handle a 1:3 mismatch so, at most, I must have a system
impedence of 150 ohms.  The tuner gets me down to 1:1.

I have not operated much on 10 meters due to the solar cycle but I have worked

local nets at 28.150 and 28.490 and can tune down to 1:1.  I suspect I can tun
e
most of the 10 meter band.

I have previously checked the antenna with an MFJ 259.  While I can't recall
specifics I did not notice the phenomena you are describing.

This is a great antenna!  With minimal operating hours I worked 60 sections in

last November's Sweepstakes on phone (slighly less on CW due to my poor CW
speed).  Also worked 60 countries in the most recent ARRL DX contest, phone an
d
CW combined, with only a few hours.  Our local club ran a loop at Field Day
last year and we worked every section except AK and YU/NWT.

Every time I walk around the back yard I get a stiff neck from looking to see
if I have room for an 80 meter loop.

If you are limited to wire antenna's, this is the one to have.  I had some
dipoles but took them down.  The loop is ominidirectional compared to the
dipole; works well compared to the dipole at broadside, beats the dipole hands

down compared to the ends of the dipole.

If there is a down side, you need at a minimum of four supports for the loop,
so if you don't have trees or a structure in the right spots it may be hard to

put one up.

KF9WX
Tim Gennett



From [e-mail] Tue Apr 23 07:42:40 1996
From: Jacob DeGlopper <[e-mail])
Newsgroups: rec.radio.amateur.antenna,rec.radio.swap
Subject: In seach of 1900 MHz mobile antenna
Date: 21 Apr 1996 21:49:02 GMT
Message-ID: <4leage$[e-mail]>

I'm looking for a 1900 MHz mobile antenna.  Ideally, I'm looking for
a glass-mount antenna terminated in a TNC connector, but I can work
with reasonable variants.  Any leads?  AES doesn't seem to list anything
above 1.2 GHz...

--
Jacob DeGlopper, EMT-A, N3RHI
[e-mail]
.




From [e-mail] Tue Apr 23 07:42:41 1996
From: Joe Foor <[e-mail]>
Newsgroups: rec.radio.amateur.antenna
Subject: Re: Inexpensive Antenna Rotors?
Date: Thu, 18 Apr 1996 15:15:05 -0700
Message-ID: <[e-mail]>
References: <[e-mail]>

In a message dated Wed, 17 Apr 1996 21:49:26 GMT kb8vba wrote:

> Any amateurs had experience with the cheap Radio Shack antenna rotor motors?

I've got two of them up in the air and they have been working fine (even
thru last years hurricanes) for VHF and UHF beams. I wouldn't expect one
to do very well with an HF beam though.

Joe Foor KF4DYS


From [e-mail] Tue Apr 23 07:42:42 1996
Newsgroups: rec.radio.amateur.antenna
From: [e-mail] (ML., Michigan, USA)
Subject: Inexpensive Antenna Rotors?
Message-ID: <[e-mail]>
Date: Wed, 17 Apr 1996 21:49:26 GMT

Any amateurs had experience with the cheap Radio Shack antenna rotor motors?
They sell for $65.  Are there any similarly priced, better quallity rotors
available?  Comments on the topic would be appreciated

kb8vba


From [e-mail] Tue Apr 23 07:42:43 1996
From: [e-mail] (Tom Bruhns)
Newsgroups: rec.radio.amateur.antenna
Subject: Re: J-Pole Gain (Was Re: Tuning a copper J-Pole.)
Date: 22 Apr 1996 15:53:32 GMT
Message-ID: <4lga1s$[e-mail]>
References: <4l8mtp$[e-mail]>

W8JI  Tom ([e-mail]) wrote:
: In article <4l8ej9$[e-mail]>, [e-mail] (Tom Bruhns)
: writes:

: >A while back I realized that a J-pole is NOT just an isolated end-fed
: >half-wave; there must be an antenna current in the 1/4 wave section.

..

: Hi Tom,

: I got in a long discussion about this a while back with someone who firmly
: believed what you just said wasn't true. Of course, I agree fully with
: you. It models, measures, and even common antenna sense indicates it works
: exactly as you describe.

: The worse possible condition for the radiation you describe is when the
: bottom of the J pole is grounded (connected to a low impedance
: termination). I can think of two ways to cure the common mode problem. One
: is to use a 1/4 wl decoupling sleeve surrounding the entire antenna, the
: other is to add a ground plane at the top and make the matching stub
: coaxial.

: The problem is rooted in use of a stub to feed an unbalanced antenna with
: no groundplane.

Hi to you, too, Tom!

Thanks for the supporting comments.  All this brings me around to
recommending what I've found to be a wonderful little book for those who
have gotten to where they want more than they can find in the usual ham
antenna books.  You may have to go looking for this one, since it appears
to be out of print...

    King, Mimno and Wing, "Transmission Lines, Antennas and Wave Guides,"
    originally published by McGraw-Hill in 1945, republished by Dover
    in 1965.  SBN: 486-61343-7

Anyway, there is a lot of discussion of linear radiators of all sorts,
including end-fed half-waves, and especially the importance of
controlling the coupling among the various radiating elements, and
decoupling those that aren't suppposed to have antenna currents on them.
Note that I don't think anyone had coined the term "J-Pole" by 1945, but
there it is, in Fig.  27.1, a half-wave end-fed by a 1/4 wave piece of
two-wire line.  But what it _also_ shows is a decoupling stub below the
1/4 wave piece, to keep antenna currents off the line below that point!
And right next to it in Fig.  27.2 is a coaxially-fed end-fed half-wave,
with a coaxial decoupling sleeve--almost exactly what Tom suggests
above, except the decoupling is with a sleeve instead of radials.
Nothing new under the sun?  Well, not quite, but this book discusses
very thoughtfully a whole lot of configurations some of you might be
taking for granted.  It has some math in it, but for the most part you
can read it without fully understanding the math anyway, and still get a
lot out of it.

--
Cheers,
Tom
[e-mail]


From [e-mail] Tue Apr 23 07:42:45 1996
From: [e-mail] (Jim Flanders)
Newsgroups: rec.radio.amateur.antenna
Subject: Re: Looking for OM experienced on half-loop antenna on 80
Date: 19 Apr 1996 18:13:46 GMT
Message-ID: <4l8l4q$[e-mail]>
References: <4khc9f$[e-mail]> <4kp5b1$[e-mail]>

The SWR on a half sloper is influenced by many things.
1) How close it is fed at the top of the tower.
2) Possible interaction with a beam on the tower.
3) The angle to the ground.
4) And most particular - how close the end of the half sloper is to

   the ground.

The half sloper can give excellent performance, however it has to be
played with to achieve success.  The best installation I have
accomplished is with five half slopers switched in direction. (See an
old ARRL antenna handbook that shows this with full slopers.)  The top
of the feed should be at least 70 feet (80 meter band) unless your
using a shortened sloper. The angle to the ground should be 60 degrees.
(or 30 degrees below the horizon)

If you have a beam on the tower above the half sloper and/or your ends
are very close to the ground, then the impedance is lowered
considerably.
This can be corrected by using a folded half sloper which doubles the
impedance, widens the bandwidth, and makes an more stable
(electrically) antenna.

feed)-------------------------------------------- (can be ladder line)
    ___________________________________________/
    |                ~64 feet
  (ground)
I hope this helps you out. Any more questions, please ask.

W0oog/5  Jim
In article <4kp5b1$[e-mail]>, [e-mail]
says...
>
>> For my 80 m activity I'm using now a half-sloper, but I'm not very
satistacted from the results. I read about the half-loop antenna. Is
there anyone exp
>> TNX for helping me.
>>
>>                                   73 de Aldo IK2ANI
>>
>>
>>
>>
>>
>>
>>
>



From [e-mail] Tue Apr 23 07:42:47 1996
From: [e-mail] (Graham Seale)
Newsgroups: rec.radio.amateur.antenna
Subject: Re: Loop Antennae
Date: Mon, 22 Apr 1996 10:40:47 GMT
Distribution: world
Message-ID: <[e-mail]>
References: <4l9db3$[e-mail]>
Reply-To: [e-mail]

In message <4l9db3$[e-mail]> Dxertom wrote:

> I've come across a couple of old, military loop antennae. I'm considering
> buying one or both.
> 1) Type CRV 69065 loop antenna that resembles a blimp and has the words
> "aircraft missle" stenciled on the side of the blimp.
>
> 2) Direction Finder Loop built for the US Navy
>
> Can either of these be used for Mediumwave reception, would they require
> much adaptation?

Hi Dxertom.

I cannot recall the type number, but from your description it sounds
like the bomb-shaped fibre case around the type of aircraft DF loop
that was fitted to nearly all DC4s and many other planes. I *think*
the rest of the DF kit was Bendix or Collins, and it operated in
conjunction with a "sense" antenna mounted in line under the plane.
The arrangement produced a "cardiod" shape pattern with a steep null
in line with the DF beacon. In operation, the loop servo would be
stable or gently hunting about the null, the position relayed to the
radio-compass instrument by 400Hz selsysns.

More years ago than I care to admit (shudder!), flying across some
fairly sparse parts of Africa, we would regularly quit using the 300kHz
NDB beacon, and tune up to medium wave stations instead, so we could
have breakfast music and news. The loop worked fine, pointing at the
distant towns. I can't remember the MW station frequencies, but I think
they were all in the range 550kHz to about 1200kHz.

73s G4WNT

--
Graham Seale


From [e-mail] Tue Apr 23 07:42:48 1996
From: Michele Piscopo <[e-mail]>
Newsgroups: rec.radio.amateur.antenna
Subject: Macintosh antenna software
Date: 18 Apr 1996 12:51:43 GMT
Message-ID: <4l5dsv$[e-mail]>

Hi,
I' m searching for antenna modelling software for Macintosh: can anyone
of you help me?

73 de Michele Piscopo, IK8JSV




From [e-mail] Tue Apr 23 07:42:50 1996
From: [e-mail]
Newsgroups: rec.radio.amateur.antenna
Subject: Magnectic Small Loops...
Date: 21 Apr 96 21:01:05 GMT
Message-ID: <[e-mail]>

Hi All:

Is anybody making any tests with small magnectic loops, such as those
used for HF work (14..30MHz, remotely tunned, like Isoloop or MFJ)?
I still doing some tests with this solutions, using copper and aluminum
and with some antenna modeller software help (Ant. opmizer, frm K6STI).
Allready know abt the lo-z that such solution have, and the mechanical
"cares" to avoid losses.
   The handbooks and other papers refers to the feeding system using
some capacitor arrange. I still trying to feed using a smaller coaxial
cable loop, at least to take advantageof the electric shield they pro
vide.
   The HF results more or less confirm what the manufacturers said. i.e.
sometimes better than a dipole at the same hight. I realize that the
electric noise is greatly reduced too. Out of band signals are vy.
atennuated too.
   I'm looking for any math. relationship between the driven shielded
loop area(or diameter), the tuned loop itself(at this case using the
biggest size I can, making the tuned cap. vy small - 3 to 8 pf) -
relationship that involves some of the standard transmition lines
impedances (50 ohm will be great!).
   Consider that the reactive portion of the loop is trimmed to zero.
I allready have a 50MHz loop working, using a 48cm dia loop, 1.5cm
dia aluminum tube, and the coupling loop had it's diameter changed
several times, but never the combination between shielded loop dia/
radiating loop tuning gave me SWR smaller than 2:1.
   To make the things easy, forgot abt polarization, radiation patterns,
and other related caracteristics: they're very dependable on my site,
hight, artificial ground, and so on...
Any Idea? Thanks in advance.
Marcus Ramos, [e-mail]


From [e-mail] Tue Apr 23 07:42:52 1996
From: [e-mail] (W8JI  Tom)
Newsgroups: rec.radio.amateur.antenna
Subject: Re: Magnectic Small Loops...
Date: 22 Apr 1996 12:21:31 -0400
Message-ID: <4lgbmb$[e-mail]>
References: <[e-mail]>

Hi Marcus,
In article <[e-mail]>, [e-mail] writes:
>
>Is anybody making any tests with small magnectic loops, such as those
>used for HF work (14..30MHz, remotely tunned, like Isoloop or MFJ)?
>I still doing some tests with this solutions, using copper and aluminum
>and with some antenna modeller software help (Ant. opmizer, frm K6STI).
>Allready know abt the lo-z that such solution have, and the mechanical
>"cares" to avoid losses.

I've done a lot of small loop work for medical and Ham applications. The
general rules are:

1.) Use a smooth round conductor, NOT stranded or braided wire.

2.) Use a compact (almost box shaped) air or vacuum insulated capacitor
with no pressure contancts.

3.) Weld or multiple bolt and solder all connections and keep them very
wide.

>   The handbooks and other papers refers to the feeding system using
>some capacitor arrange. I still trying to feed using a smaller coaxial
>cable loop, at least to take advantageof the electric shield they pro
>vide.

That "electrical shield" does absolutely nothing at all to improve balance
or E field coupling.  Do not worry about it.

It can improve matching over wide frequency ranges because the broken
shield and cable acts like a L network at the higher bands.

>   The HF results more or less confirm what the manufacturers said. i.e.
>sometimes better than a dipole at the same hight. I realize that the
>electric noise is greatly reduced too. Out of band signals are vy.
>atennuated too.

Electrical noise is NOT reduced unless the antenna is in the near field of
the noise, within a half wavelength or less. Electrical noise is
electromagnetic radiation, just like a signal.

A dipole will always be better for signal, but not much better. My 3 foot
loop is one dB down from a dipole on ten meters, and 6 dB down on 10 MHz.


>   I'm looking for any math. relationship between the driven shielded
>loop area(or diameter), the tuned loop itself(at this case using the
>biggest size I can, making the tuned cap. vy small - 3 to 8 pf) -
>relationship that involves some of the standard transmition lines
>impedances (50 ohm will be great!).

It's mostly cut and try, because the Q of the loop varies wildly. So any
calculation will never be true in practice.

You can always get the SWR to 1:1 by changing the size of the coupling
loop. You may need a L network for lowest SWR over broad bandwidth.

73 Tom


From [e-mail] Tue Apr 23 07:42:53 1996
From: [e-mail] (Rob Whitacre)
Newsgroups: rec.radio.amateur.antenna
Subject: Re: Mobile Antenna
Date: 19 Apr 1996 14:17:49 GMT
Message-ID: <4l87ad$[e-mail]>
References: <[e-mail]>

In article <[e-mail]>, [e-mail] says...
>
>What is the best HF mobile antenna?  I plan to mount it on the back
>of a Toyota Land Cruiser.  Opinions, please.
>Murray, W5XH

My vote is for the SGC smart tuner + whip

Rob WB8WQA



From [e-mail] Tue Apr 23 07:42:53 1996
From: Dustin Howell <[e-mail]>
Newsgroups: rec.radio.amateur.antenna
Subject: Need Tower Calculations
Date: Thu, 18 Apr 1996 20:00:09 -0700
Message-ID: <[e-mail]>

Hello,
  Does anyone know how gain increases as height increases on a tower?  I
am looking for some math so that we can figure a good height to install
some 50 mhz antenna's for a repeater.  Any info is appreciated.

73's
[e-mail]


From [e-mail] Tue Apr 23 07:42:55 1996
From: [e-mail] (FORREST GEHRKE)
Newsgroups: rec.radio.amateur.antenna
Subject: Re: Propagation Query
Message-ID: <[e-mail]>
Date: Wed, 17 Apr 96 11:05:00 -0300
Distribution: world
Reply-To: [e-mail] (FORREST GEHRKE)
References: <4kprm9$[e-mail]>

WT> 160, 80 and 40 have poorer propagation as sunspots increase. DX is
WT> better on those bands at the minimum.

WT> If you like the lowest HF bands, you'll have to look harder as
WT> sunspots increase.

I don't think you're right about this, Tom.  It's the highly
ionized F layer that accounts for the great DX paths on any
HF band.  The difference at minimums is that absorptive
low band D layer ionization, which is slow to form even during
sunspot maximums, is almost non-existent.

The best long path openings on 80M that reach down all the way
to Florida, occur during sunspot maximums.  This past winter
there were hardly any such openings even though I could hear
W1 and VE1 & 2 working them; I could just barely hear a few JA's.

--k2bt
 * RM 1.3 02583 * Nature can only be commanded by being obeyed--Francis Bacon


From [e-mail] Tue Apr 23 07:42:56 1996
Newsgroups: rec.radio.amateur.antenna
From: Tom Skelton   WB4iUX <[e-mail]>
Subject: Re: Propagation Query
Message-ID: <[e-mail]>
Reply-To: [e-mail] (skeltt)
References: <4l4j6i$[e-mail]>
Date: Thu, 18 Apr 1996 17:21:45 GMT


>==========WB3U, 4/17/96==========
>
>Two nights ago I tuned up on 40M about 3:00 AM and the band was
>almost completely DEAD.  All I could hear were two SW broadcasters,
>both about S3, and almost no background noise.  The next night it was
>somewhat better, but still not much fun.  80M has also been been in
>bad shape lately, with most propagation being either very short or
>very long (off the continent).
>
>Someone please tell me this is all just a temporary fluke.  My late
>night CW is really starting to suffer.
>
>73,
>Jack  WB3U
>

I can't keep up completely with you, Tom, Gary and Cecil on all of your
antenna and balun discussions, but I can sure 'nuff let you know what is
happening on the low bands.  We have 2 things going on:

1.  the MUF is VERY low, much lower than 7 MHz on virtually all nights
and certainly lower than 3.5 MHz on many nights  -- this is just a common
result of being at the bottom of the sunspot cycle (the first
time somebody
told me 40 meters dies at night at the bottom of the sunspot
cycle I thought
he was a fool -- I was the fool)

2.  on or about the 16th, we had a solar disturbance that probably
made the condx worse (you're only going to hear the loudest of the loud)

My only suggestion is to get an antenna up for 160 meters.  I am
suffering right along with you -- I am away from home virtually all week
and only home on weekends.  Thus, I want some GOOD conditions when
I am home and it just hasn't been that way.   When mother nature MAKES
me get up at 3 am ( a consequence of turning 40? ), I just do my
business
and go back to bed -- no more trips to the radio room 'cause I
know it's a
waste of time.  I just spoon-up next to my wife and go back to
sleep.  Of
course, now my wife isn't complaining about me being in the
radio room in the
middle of the night..... ;-)

73, Tom WB4iUX
[e-mail]



From [e-mail] Tue Apr 23 07:42:57 1996
From: [e-mail] (Walter R Francis)
Newsgroups: rec.radio.amateur.antenna
Subject: Re: Question abt 2 meter mobile ant.
Date: 17 Apr 96 23:31:56 -500
Message-ID: <[e-mail]>
References: <497cc$103915.8b@NEWS> <4kgae8$[e-mail]> <[e-mail]>
Reply-To: [e-mail]


On 13-Apr-96 11:55:40, Gerald Brentnall articulated:

>At the risk of starting a big debate on this issue, I would recommend
>you purchase a magnetic mount, 1/4 wave antenna.  I would recommend

1/4 wave antennas work fine with local repeaters, etc, but there is one
problem I have found with them.  As crazy as it may sound, I have one mag-
mount 1/4 2m, 1 NMO mount 1/4 2m, and another that is optimized for 70cm, but
also 1/4 wave on 2m, and all receive intermod MUCH worse than any gain antenna
I have.  Going from a Larson 2/70 at around 2.4dB gain, to a Comet at >5dB.
I suppose it's due to being closer to 152, but I don't know.  Just know I've
tried it on all the antennas, and the 1/4 wave make my poor IC281 unbearable
downtown when it's okay on the gain antennas.

Have to buy a filter one of these days, wish it wasn't necessary!

Weird stuff.



--
-.-. --.- -.-. --.- -.-. --.- -.-. --.- -.-. --.- -.-. --.- -.-. --.- -.. .
.  Walter Francis                                               _. KT4LH  .
-                 Alinco DJ580  Icom 281  Kenwood 530S         o:o        -
.  [e-mail]                                   Life begins on 80  .
--... ...-- --... ...-- --... ...-- --... ...-- --... ...-- --... ...--  ..



From [e-mail] Tue Apr 23 07:42:58 1996
From: (Gary) [e-mail]
Newsgroups: rec.radio.amateur.antenna
Subject: Re: Screwdriver Antenna
Date: 18 Apr 1996 12:24:51 GMT
Message-ID: <4l5caj$[e-mail]>
References: <Pine.SOL.3.91.960417175003.27894B-100000@bingsun1>

>   tom <[e-mail]> writes:
>  What is a Screwdriver Antenna?
>  I have been hearing about this type of antenna recently on the air but
>  don't know what it is? Is this a mobil antenna?
>  HELP  HELP HELP HELP HELP?
>
>  Tom   [e-mail]
>
>
>
>>>>
The Screwdriver antenna derives its name from the cordless screwdriver motor
that operates it's movable coil.  The movable PVC based coil sets inside of
a 2" metalic tube and can be moved in and out exposing part or all of
the coil, thus all band operation can be achieved.

                    I hope this helps    "73" Gary KF9CM



From [e-mail] Tue Apr 23 07:42:59 1996
From: [e-mail] (W. D. Milner)
Newsgroups: rec.radio.amateur.antenna
Subject: Re: Sports car Antennas??
Date: Mon, 15 Apr 1996 00:36:46 GMT
Message-ID: <4ks8lo$[e-mail]>
References: <4kklqh$[e-mail]>
Reply-To: [e-mail]

qwick@???????.com (Qwick) wrote:

>I'm currnetly drin=ving a red '83 Trans-Am..
>I am using a cheap walmart Antenna that cam with  my Midland radio
>I need to know of an antenna that won't look "gay" or "stupid" on my
>car.  I do not want a huge 'friggin whip.  I have seen CB antenna's
>that look like cellular phone antenna's.  Nyone know if they are any
>good?  Please give any and all suggestions.  I could also use mods for
>that cheap midland.

How can an antenna look "gay" let alone "stupid"? :)

Anyway, the cellular look alikes work ok, just realize that cell phone
thefts are quite high and while you may not have one, an antenna like
that may invite a break in to see.



---------------------------------------
Dean, VE1CBF        [e-mail]
[e-mail]  FN96VC

- - ...  ... - -




From [e-mail] Tue Apr 23 07:43:00 1996
From: [e-mail] (WB3U)
Newsgroups: rec.radio.amateur.antenna
Subject: Re: suggest a balun, please
Date: Mon, 22 Apr 96 17:17:57 GMT
Message-ID: <4lgmkb$[e-mail]>
References: <claude.830166974@bauv111>

   [e-mail] (Claude Frantz) wrote:

>What is a good choice for a broadband, broad Z balun to be used
>between the balanced feedline of a dipole and the unbalanced
>match box ? Note that the Z can be very variable.

The two best are the coaxial coil balun and the type of choke balun
that consists of bifilar turns on a rod or toroid.  However, even
these won't assure balance or accurate impedance reflection over a
wide impedance/frequency range.  Unless some method is used to adjust
the feedpoint impedance of the system (such as variable line length),
the best method of feeding a non-resonant dipole is still a link-
coupled tuner.

73,
Jack  WB3U


From [e-mail] Tue Apr 23 07:43:01 1996
From: [e-mail] (John Rouse)
Newsgroups: alt.radio.scanner,alt.radio.pirate,aus.radio,rec.radio.amateur.antenna,rec.radio.amateur.equipment,rec.radio.amateur.misc,rec.radio.scanner,rec.radio.shortwave,uk.radio.amateur
Subject: Re: Sxxx, my FM-25 is Fxxxxx! What to do??
Date: Wed, 17 Apr 1996 20:40:18 GMT
Message-ID: <4l5vun$[e-mail]>
References: <[e-mail]> <4ijvsq$[e-mail]> <4ikqld$[e-mail]> <4jmrld$[e-mail]> <[e-mail]> <4k0dt6$[e-mail]> <4k19av$[e-mail]> <4k3p56$[e-mail]> <4k5rmr$[e-mail]> <4kjb9v$[e-mail]> <4komm1$[e-mail]> <4kqaue$[e-mail]>


 This appears to be the idiotic thread that refuses to die!!!

73, John KA3DBN

===
John L. Rouse                  Packet:[e-mail]
Capital-Gazette Communications Fax: [phone]
Annapolis, Maryland            Voice mail: [phone] X200
               =========================
[e-mail]             [e-mail]



From [e-mail] Tue Apr 23 07:43:02 1996
From: [e-mail] (CHARLES J. MICHAELS)
Newsgroups: rec.radio.amateur.antenna
Subject: Re: The Transmitter Chassis (Was MFJ Artificial Ground)
Date: 17 Apr 1996 20:02:56 GMT
Message-ID: <4l3ipg$[e-mail]>


Jack,
        After all the discussion on this thread, a balanced or coax
feedling with no net current flow to the space around it will not
radiate.  If there is a net current flow then like any other current
flow it will cause radiation depending on fe/// frequency etc... i.e.
it is an antenna.

Charlie, W7XC
--


From [e-mail] Tue Apr 23 07:43:04 1996
Newsgroups: rec.radio.amateur.antenna
From: [e-mail] (Steve Ellington)
Subject: Re: Transmission line question...
Message-ID: <[e-mail]>
References: <4l8g0d$[e-mail]>
Date: Fri, 19 Apr 1996 19:32:57 GMT

Hmmmm. Would this be unbalanced?


: Does anyone have a formula for the impedance of a two-wire transmission
: line where one conductor is a different diameter than the other?  My
: usual references seem to only cover the equal-diameters case.

Steve Ellington [e-mail]  Louisville, Ky


From [e-mail] Tue Apr 23 07:43:05 1996
From: [e-mail] (Wes Stewart)
Newsgroups: rec.radio.amateur.antenna
Subject: Re: Transmission line question...
Date: Fri, 19 Apr 1996 18:44:51 LOCAL
Message-ID: <[e-mail]>
References: <4l8g0d$[e-mail]> <[e-mail]>

In article <[e-mail]> [e-mail] (Steve Ellington) writes:
>From: [e-mail] (Steve Ellington)
>Subject: Re: Transmission line question...
>Date: Fri, 19 Apr 1996 19:32:57 GMT

>Hmmmm. Would this be unbalanced?


>: Does anyone have a formula for the impedance of a two-wire transmission
>: line where one conductor is a different diameter than the other?  My
>: usual references seem to only cover the equal-diameters case.

>Steve Ellington [e-mail]  Louisville, Ky


Let d1 = diameter of conductor #1,
    d2 = diameter of conductor #2,
and  D = the center-to-center spacing

then for d1, d2 << D

Zo = (276/e^.5)* log10((2*D)/(d1*d2)^.5)

where e = dielectric constant and all dimensions are in the same units.

from Reference Data for Radio Engineers, fourth edition p 592.

73, Wes -- N7WS


From [e-mail] Tue Apr 23 07:43:06 1996
From: Bruce Burke <[e-mail]>
Newsgroups: rec.radio.amateur.antenna
Subject: Re: Tuning a copper J-Pole.
Date: Thu, 18 Apr 1996 11:06:45 -0400
Message-ID: <[e-mail]>
References: <[e-mail]>

Kevin Muenzler wrote:
>
> on 15 Apr 1996 05:23:38 -0400 [e-mail] (Marine7) writes:
>
> >I constructed a copper J-Pole for 2-meters, but I am unable to get the SWR
> >below 3:1.    The SWR will go to close to 1:1 if I bend the stub toward
> >the long pole, but then I get signal reports that indicate a hum that
> >resembles a weak 60hz tone.  If I bend the stub back to parallel, the SWR
> >goes up again to above 3:1.  Moving the feed line clamps up or down moves
> >the SWR around, but not below 3:1.  I am new at the antenna building
> >hobby, and would appreciate some tips concerning the tuning of,
> >specifically, a copper J-Pole.
> >
> >Thanks, 73, Jim Temple, KF4ICZ.
Jim,

One of the things I found critical was the inductance in the feed. I used
a 1/2 inch wide strip of copper from the antenna connector to the feed point.

I also had to add about an inch to my first one because I discovered that
the natural resonant point was high. You might want to try and find this first
,
then you will know what to change on the length,

73,

Bruce, WB4YUC


From [e-mail] Tue Apr 23 07:43:07 1996
From: [e-mail] (Cecil A. Moore~)
Newsgroups: rec.radio.amateur.antenna
Subject: Re: W6KKT VISALIA MOBILE "SHOOTOUT" (LAST CALL)
Date: 21 Apr 1996 17:02:55 GMT
Distribution: world
Message-ID: <4ldpnv$[e-mail]>
References: <4l84qa$[e-mail]>

In article <4l84qa$[e-mail]>,
Jesse Touhey  <[e-mail]> wrote:
>Last Call: The W6KKT mobile antenna system field strength trials will be
>held tomorrow (Saturday, April 20th) starting at 9:00am at the U.S.Towers

Hi Jesse, It was great fun and I probably would have missed a good time
if you hadn't posted your notices here. If I read the results correctly,
my extended 40m Hamstick and SGC-230 autotuner held its own against some
bugcatchers and screwdrivers.

73, Cecil, KG7BK, OOTC  (not speaking for my employer)


From [e-mail] Tue Apr 23 07:43:09 1996
From: [e-mail] (Don Phelps)
Newsgroups: rec.radio.amateur.antenna
Subject: Re: Which is better on 80
Date: Tue, 16 Apr 1996 07:51:00 GMT
Message-ID: <[e-mail]>
Distribution: world
References: <4ku0bt$[e-mail]> <4kjg9c$[e-mail]> <4k3sdl$ppi@dub-


Hi Jim,

 >My best antenna on 80 was full length 135 ft dipole feed with
 >450 ohm ladder line from a Johnson Matchbox.
 >I used multiple conductors spaced 10 feet apart to widen
 >the bandwidth and lower impedance swings.

 >To lower losses in the ground reflection, I oriented the antenna
 >vertically, hanging down from a tall limbless tree trunck
 > which leaned over, all being on top of a knoll.
 JG>
 JG> That is probably an excellent DX antenna on 80.  I would have to space
 JG> my antenna close to a tall fir tree to do that, but it might be worth
 JG> it. I don't like the low angle levels and pattern I get with dipoles on
 JG> 80.

From Lake Tahoe in California, I had very good results.
Received comments such as one of three loudest signals on the band etc,
when I came back to a mobile in Chicago.  He wouldn't believe I
was in California.

I pulled the bottom out away from the base of the tree to get more
separation from the verticle oriented tree.  The feedline was near,
but not quite perpendicular to the antenna.  As long as it'n not
lossy, you're loud somewhere! :-)

 JG> Does the close proximity of the ground to only one end of the dipole
 JG> upset the balance of the system and cause feedline radiation?  If you
 JG> run an amplifier any feedline radiation can cause havoc in the shack.

I operated full legal power from a pair of 4-1000s, and didn't have
problems.

 JG> I currently have a 65' vertical up the side of a Cedar tree with a few
 JG> long radials.  This works okay, not great but it does do a good job of
 JG> attenuating the local signals while leaving the DX as strong or
 JG> slightly better than a 50' high dipole.  Attenuates local noise too.

I lived in Alpine Meadows, which is a weekend ski resort community with
burried utilities.  During the week with no one arround, I had low
levels of local noise.

 JG> WA7LDV

The reason I was drawn to the vertical half wave dipole, was to
avoid the need to install a ground radial system.
I was located on top of a rocky hill, and was impractacle to bury
radials.
I figured since the currant flows in the ground goes through the
reflected image cross section of ground, the currant maxima has
a cross section of 68 feet times 2 pie.  Therefore, most of the
gain improvement over a grounded quarter wave with a poor ground system,
comes from reduced losses.  For me, the additional height was cheaper
than all those radials!

The tuned feeders made the antenna work wonders on 40 as a colinear
verticle.  The antenna net gave me very good reports worldwide.

 JG> [e-mail]

Don, N6MCE



... [e-mail]
___ Blue Wave/386 v2.30 [NR]


From [e-mail] Tue Apr 23 07:43:10 1996
From: [e-mail] (CHARLES J. MICHAELS)
Newsgroups: rec.radio.amateur.antenna
Subject: Re: Which is better on 80: 80 m dipole or G5RV (see text) ?
Date: 13 Apr 1996 19:15:37 GMT
Message-ID: <4kougp$[e-mail]>


Jim said -
(concerning a so-called G5RV)
                              It seems that since the upper part of the
feedline is a radiator, and the tower was grounded, it destroyed the
usefulness of the antenna.  Most G5RV installations need it to be
put up as a flat top and the feed line drop vertically for the first
32 feet or so.  If you can't do this, than I would prefer the 80 meter
dipole.

Jim,
        What makes you think that the upper part of the feedline is a
radiator?

Charlie, W7XC
--


From [e-mail] Tue Apr 23 07:43:11 1996
Newsgroups: rec.radio.amateur.antenna
From: [e-mail] (Pete Soper)
Subject: Re: Zepp, Double Extended - Why?
Date: Thu, 18 Apr 1996 14:38:21 GMT
Message-ID: <[e-mail]>
References: <4kneet$[e-mail]>

[e-mail] (CHARLES J. MICHAELS) writes:


>       The only reason to cut an antenna to a rather exact resonant
>half wave length is to get a pure resistive feedpoint impedance.
>       A virtue of the so-called EDZ is that it maintains essentially
>a doughnut pattern over abvout a 2 to 1 frequency range and at the highter
>frequency exhibits some gain over a half wave even if some powr does go
>into the developiong side lobes because the main lobes bvecome slightly
>thinner .

I spent a long time modeling this antenna before going with a Lazy-H
for my 3rd HF antenna. (Still have interest for the future however)

EZNEC predicts dipole-like broadside lobes but with 30-35 degrees horizontal
beamwidth at the 1X frequency. Sort of like a donut that was yanked from
two sides :-) The usual four diagonal lobes of a longwire antenna are
predicted at the 2X frequency. I've seen certain (vertical) phased arrays of
these 5/4 wl elements show broadside radiation on multiple frequencies, but
not the plain, single element version.

If you can demonstrate broadside lobes on two frequencies I'd be interested
in the details.

Regards,
Pete
KS4XG


From [e-mail] Sun Apr 28 13:08:54 1996
From: [e-mail] (John Stroppel)
Newsgroups: rec.radio.amateur.antenna
Subject: Re: 160 meter antenna
Date: 23 Apr 1996 20:44:10 GMT
Distribution: world
Message-ID: <4ljfeq$[e-mail]>
References: <4lggm3$[e-mail]>

What about a terminated long wire?

John WA0VYZ

--
 John Stroppel                         | Internet: [e-mail]
 The University of Iowa - Hygienic Lab | Amateur Radio: WA0VYZ
 Oakdale Research Campus, OH-M7A       | Voice:    [phone]
 Iowa City, IA   52242                 | Fax:      [phone]


From [e-mail] Sun Apr 28 13:08:55 1996
From: [e-mail] (Michael W. Smith II)
Newsgroups: rec.radio.amateur.antenna
Subject: Re: 6 meter J- Pole
Date: Mon, 22 Apr 1996 19:59:14 GMT
Message-ID: <4lghe8$[e-mail]>
References: <4lg43t$[e-mail]>
Reply-To: [e-mail]

[e-mail] (Michael W. Smith II) wrote:

>It seems that there is a lot of action/questions about J poles....I'm
>looking to build a 6 meter jpole.  There are some articles about
>construction, but there are in the 1950's magazines.  I was wondering
>if anyone had built a 6 meter j pole and could give me some ideas on
>how to build one, or some starting dimensions.  Thanks alot!!

>73's
>N5TGL
>Michael W. Smith II

Welllllll, seems like I didn't read the previous postings too well.  I
caught the URL for the jpoles...but if anyone has any other ideas or
previous magazine articles....send them on: [e-mail]
Thanks again!




From [e-mail] Sun Apr 28 13:08:56 1996
From: [e-mail] (Gary V. Deutschmann, Sr.)
Newsgroups: rec.radio.amateur.antenna
Subject: Re: 6 meter J- Pole
Date: Thu, 25 Apr 1996 01:35:30 GMT
Message-ID: <4lml0i$[e-mail]>
References: <4lg43t$[e-mail]>

[e-mail] (Michael W. Smith II) wrote:

>It seems that there is a lot of action/questions about J poles....I'm
>looking to build a 6 meter jpole.  There are some articles about
>construction, but there are in the 1950's magazines.  I was wondering
>if anyone had built a 6 meter j pole and could give me some ideas on
>how to build one, or some starting dimensions.  Thanks alot!!

>73's
>N5TGL
>Michael W. Smith II

I use a mirror image J on 6-m....
By using a simple solenoid, I can flip it from vertical to horizontal.

Plans available on my web page http://www.inlink.com/~raiar

TTUL - 73+ de Gary - KG0ZP






From [e-mail] Sun Apr 28 13:08:57 1996
From: [e-mail] (WB3U)
Newsgroups: rec.radio.amateur.antenna
Subject: Re: 80 Meter Helix
Date: Fri, 19 Apr 96 08:34:35 GMT
Message-ID: <4l7qpu$[e-mail]>
References: <4l3k9s$[e-mail]> <4l5mkp$[e-mail]>

   [e-mail] (W8JI  Tom) wrote:

>I have a top loaded 35 foot vertical on 80, with 60 or 80 1/4 wl long
>radials. That small vertical ties my dipole ( and the dipole is 135
>feet high ) into Europe.

Tom, was just wondering why you top-loaded your vertical?  Did you do
this to eliminate the need for a tuned matching network at the feed?

73,
Jack  WB3U


From [e-mail] Sun Apr 28 13:08:58 1996
From: [e-mail] (John Moore)
Newsgroups: rec.radio.amateur.antenna
Subject: ? R5 Question ?
Date: 22 Apr 1996 20:03:19 GMT
Message-ID: <[e-mail]>

I bought a fairly new R5 at a hamfest.  The exterior of the fiberglass
section near the bottom looks and feels like fiberglass cloth with little
resin.  I guess that this is the result of weather.  My concern is that
when this gets wet it will absorb water and raise havoc with the swr. The
counterpoises attach in that area and the section insulates the antenna
from the mast. If this is a problem, should I paint the area with new
resin?  Or tape over it? Or cover it with plastic? Any ideas???

Thanks...AB5YQ John


From [e-mail] Sun Apr 28 13:08:59 1996
From: [e-mail] (hank heidt)
Newsgroups: rec.radio.amateur.antenna
Subject: AEA IsoLoop 10-30 Does it really work??
Date: 22 Apr 1996 15:41:46 GMT
Message-ID: <4lg9bq$[e-mail]>

AEA IsoLoop 10-30 Does it really work??

I live in an apartment building And I would like to receive and if
possible transmit in the HF bands.  Has anybody used the  AEA IsoLoop  10
to 30 MHz loop antenna? Is so is it practical solution for receiving and
transmitting in the HF bands or is not worth the money.

Any other suggestions for Antennas that work in limited spaces?

Thanks in advance

-Hank
N4AFL



From [e-mail] Sun Apr 28 13:09:00 1996
From: Jonathan Helis <[e-mail]>
Newsgroups: rec.radio.amateur.antenna
Subject: Re: AEA IsoLoop 10-30 Does it really work??
Date: 27 Apr 1996 16:57:25 GMT
Message-ID: <4ltjll$[e-mail]>
References: <4lg9bq$[e-mail]> <[e-mail]>

Richard Kiefer <[e-mail]> wrote:
>hank heidt wrote:
>>
>> AEA IsoLoop 10-30 Does it really work??
>>
>> I live in an apartment building And I would like to receive and if
>> possible transmit in the HF bands.  Has anybody used the  AEA IsoLoop  10
>> to 30 MHz loop antenna? Is so is it practical solution for receiving and
>> transmitting in the HF bands or is not worth the money.
>>
>> Any other suggestions for Antennas that work in limited spaces?
>>
>> Thanks in advance
>>
>> -Hank
>> N4AFL

I have used an AEA Isoloop from an apartment and from a condo, and have
had good results.  Working mostly 30 and 17, I have worked all over the
U.S.  I haven't worked any DX on it yet though.

One thing I've noticed is that it's sensitive to anything metal around
it.  This causes tuning up problems.  Sometimes opening it up and moving
the loop around solves this problem.  Putting the antenna in another
location also helps.

Another soulution to the apartment problem is the MFJ 1621 54 inch whip.
The Isoloop is a better performer, but the little MFJ will go down to 40
meters.  From my former home near New Orleans, LA, I worked all the way
to Georgia on 40 CW in the daytime.  Not spectacular, but it did work.

Another apartment antenna I used was simplicity itself.  The apartment I
was in had a balcony(I always rent upper floor apartments with balconies
if possible, they make good antenna farms<grin>), so I built one there.
I bought some antenna wire from the neighborhood Radio Shack, along with
some Egg insulators, and built a square loop on the balcony.  I had it
set up so I could run it open or closed, and fed the thing with TV
Twinlead into a tuner.  I think it resonated on around 22 mhz, I tested
it with an old MFJ SWR analyzer(a necessity for doing antenna experiments
IMHO), and that was the reading it showed.  Using the tuner, I could load
it up on various higher bands(20 meters and up), it wouldn't load below
30 unfortunately.  One evening late, running 50 watts CW on 20, I heard a
German calling CQ, shooting for the stars, I called him back, and he
returned and gave me good signal report!  Not bad less than $10 worth of
parts and a homebrew tuner a guy gave me.

An apartment dwelling ham here in Baton Rouge, has a wire beam pointed at
Europe on his ceiling, and it works well for him.  Also try stringing a
loop inside the apartment, that's been known to work as well.

>The bandwidth is very narrow so you
>have to retune them often as you tune across the band but they act as a
>preselector.  Probably expect -2 to -4 dbd gain for the same height.
>

That is true, on 30 meters, the bandwidth is very narrow, but it does
work still.  On the higher bands, the bandwidth is a little better.  The
thing also takes practice to tune, but again, it can get you out.

>Other possibilities are to put a simple dipole in the attic of your
>building or lay a dipole on the roof.  But in any case get the antenna as
>high as possible.  Good luck.
>
>Dick Kiefer, K0DK

That might work out as well.  If you can, try to get a copy of the W1FB
Antenna Notebook from the ARRL.  It's an excellent resource, it has some
good ideas for limited space antennas in it.  Another ARRL book, Low
Profile Amateur Radio, also has some good ideas in it.  It talks about
building loops and even getting out of the apartment and going mobile.

With a little work and a little creativity, apartment dwellers can enjoy
ham radio just as easily as that guy out on the farm with the 80 meter
beam!

Good Luck!

73,

Jon Helis, KB5IAV



From [e-mail] Sun Apr 28 13:09:02 1996
From: Bill Meara <[e-mail]>
Newsgroups: rec.radio.amateur.antenna
Subject: Re: Antenna Theory Question
Date: 23 Apr 1996 11:07:21 GMT
Message-ID: <4lidl9$[e-mail]>
References: <4ld726$[e-mail]> <4lgbke$[e-mail]>

This is a multi-part message in MIME format.

---------------------------------20360948314652
Content-Transfer-Encoding: 7bit
Content-Type: text/plain; charset=us-ascii

Tom, Graham: I sent this attachment as an e-mail to Tom, but thought it
might be of interest to others. If the attachment doesn't get attached,
perhaps Tom could post it for me (problems with my software here).
Graham:  Great posting!  I will carry to work with me today and poder it
at luch time!  73 to all!   Bill   N2CQR/HI8

---------------------------------20360948314652
Content-Transfer-Encoding: quoted-printable
Content-Type: text/plain

At 11:50 AM 4/22/96 -0400, you wrote:
>You know you've poised an interesting question, one that was no my
>understanding of how the system worked.
>
>None of my textbooks have anything relating to the example and reasoning that
>displacement currents would produce EM waves. What book were you referring to
>that had the picture??


Tom : Displacement current is a fascinating subject.  Lots of controversy and
lots of different interpretations!  Right now I'm look=
ing at the Spanish language version of "Basic Electromagnetism and its Applica
tions"  by A.C. Compton, Published by: Chapman and Hil=
l, London 1986.   The chapter entitled "Electromagnetic Field"  has the diagra
m showing the "displacement current" through the capac=
itor generating a magnetic field... just like an ordinary current.  Now, if th
e capacitor has a material dielectric, you could argue=
 that the "current" results from the polarization ("displacement") of the atom
s in the dielectric material.  But things get real int=
eresting when they tell you that the magnetic field even shows up when the die
lectric is a vacuum!  This is where people start talki=
ng about ether.

I got into a very long and interesting e-mail chat with an older fellow in Eng
land who had witnessed all the great theoretical debat=
es about all this. He told me that discussions of the nature of the displaceme
nt currents filled radio magazines in the 20's and 30'=
s!  This same very learned gent does not dismiss entirely the notion of ether.
  The way he sees it, if we say that "space" has chara=
cteristics (pemittivity, permeability, characteristic impedance) we are in a s
ense saying there is an ether.  He claims Einstein wen=
t along with this. Makes sense to me!

Actually this notion of the possibility of "displacement currents" in space (e
ven if it is a crutch, or something we can't explain) =
makes it easier (for me) to visualize EM Waves. Start from the E field in spac
e.  Since it is changing, it is polarizing the dielect=
ric of space, thus creating a changing displacement current which in turn gene
rates an E field in space... A Wave is Launched!

I think most people who deal with this subject do not probe very deeply.  Many
 are willing to just repeat the lines the memorized in=
 school:  A changing electric field creates a changing magnetic field ... and
vice versa.   So in the case of the dipole, where we d=
efinitely have a changing electric field 90 degrees out of phase with the curr
ent induced magnetic field, we should have a second EM=
 wave.  Maybe this second wave contributes to the figure 8 radiation pattern o
f the dipole?   Enquiring minds want to know!

I'm happy to talk to a fellow amateur about this.  I just got a response from
a scientist at the CERN in Switzerland.  I'm sure it h=
as a lot of good info, but I can't pick head nor tails out of it!

Let me know what lyou think of all this.


>

---------------------------------20360948314652--


From [e-mail] Sun Apr 28 13:09:03 1996
From: [e-mail] ()
Newsgroups: rec.radio.amateur.antenna
Subject: Re: Antenna Theory Question
Date: 23 Apr 1996 15:15:19 GMT
Message-ID: <4lis67$[e-mail]>
References: <4l6o6a$[e-mail]> <4l80tb$[e-mail]> <4ld726$[e-mail]> <[e-mail]>

Hi Graham,

>The way our "displacement currents" came about is not far removed from
>the way Lavoisier conjured a "new" substance possessing "negative weight"
>to explain the increase in weight of mercury as he drove off the
>"Phlogiston" by heating.

OK, but there is an important difference between a model that's simply
wrong because it leeds to incorrect predictions and one that is right.


>About equal rights for E-Fields
>^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

From what I learned, a small loop is a device in which radiation
is essentially caused by a AC magnetic field and a short (Herzian)
dipole radiates essentially as the result of the AC electric field.

Both are quite equivalent.

73, Moritz DL5UH




From [e-mail] Sun Apr 28 13:09:05 1996
From: [e-mail]
Newsgroups: rec.radio.amateur.antenna
Subject: Re: Antenna Theory Question
Date: 23 Apr 1996 22:30:27 GMT
Message-ID: <4ljlm3$[e-mail]>
References: <4ld726$[e-mail]> <4lgbke$[e-mail]> <4lidl9$[e-mail]>

Bill Meara ([e-mail]) wrote:
>Tom : Displacement current is a fascinating subject.  Lots of
>controversy and lots of different interpretations!  Right now I'm
>looking at the Spanish language version of "Basic Electromagnetism and
>its Applications"  by A.C. Compton, Published by: Chapman and Hill,
>London 1986.   The chapter entitled "Electromagnetic Field"  has the
>diagram showing the "displacement current" through the capacitor
>generating a magnetic field... just like an ordinary current.  Now, if
>the capacitor has a material dielectric, you could argue that the
>"current" results from the polarization ("displacement") of the atoms
>in the dielectric material.  But things get real interesting when they
>tell you that the magnetic field even shows up when the dielectric is a
>vacuum!

... stuff deleted by me ....

>I think most people who deal with this subject do not probe very
>deeply.  Many are willing to just repeat the lines the memorized in
>school:  A changing electric field creates a changing magnetic field
>... and vice versa.   So in the case of the dipole, where we definitely
>have a changing electric field 90 degrees out of phase with
>the current induced magnetic field, we should have a second EM
>wave.  Maybe this second wave contributes to the figure 8 radiation
>pattern of the dipole?   Enquiring minds want to know!
>
>I'm happy to talk to a fellow amateur about this.  I just got a
>response from a scientist at the CERN in Switzerland.  I'm sure it has
>a lot of good info, but I can't pick head nor tails out of it!
>


There is no controversy whatsoever over displacement current, at
least among physicists. Everyone agrees it is another name for the time
derivative of the displacement field D. I don't believe there ever was
any scientific controversy over this.

There is a well known solution for the radiation from a dipole
antenna. The methods of solution are numerous and if the system
calculated is the same, they agree with each other and with measurements.
There is no mysterious second wave radiated.

Some questions here are ones of philosophy, not physics. To be
physics, you have to be able to devise an experiment to test your
hypothesis.  The experiment to see if there is a "second wave" from a
dipole antenna has been done and there isn't one. Questions like is a
displacement current a polarization current in the ether, only make
sense in physics if you can devise an experiment that would have
different outcomes if the answer is yes or no. If you want to postulate
a Lorentz invariant ether that is exactly described by Maxwell's
equations with no other consequences, then this becomes a philosophical
question since no experiment can tell the difference between your
postulate and Maxwell's equations.

I occasionally wonder why other hams get enamored with the time
derivative of the displacement field being called the displacement
current but don't also get similarly enamored with the time derivative
of the magnetic flux density as a magnetization current. This is of course
a psychology question. :-)

73, Kevin [e-mail]


From [e-mail] Sun Apr 28 13:09:06 1996
From: Bill Meara <[e-mail]>
Newsgroups: rec.radio.amateur.antenna
Subject: Re: Antenna Theory Question
Date: 23 Apr 1996 23:40:51 GMT
Message-ID: <4ljpq3$[e-mail]>
References: <4l6o6a$[e-mail]> <4l80tb$[e-mail]> <4ld726$[e-mail]> <[e-mail]>
To: [e-mail]

Graham: I spent some time under a tree at lunch hour today, pondering
your last posting on antenna theory.  I liked it very much.  Your
observations on the relationship between mathematics and reality in all
this was right on target. Reminded me of something I read in an old ham
book (VHF Handbook by Herbert Brier and Bill Orr, 1974)

"Maxwell pictured empty space as full of elastic ether - a sort of
jelly-like substance that would quiver when prodded by an electromagnetic
wave, but did nothing on its own. More sophisticated mathematical
concepts of electromagnetic phenomenon were later developed by Lorentz of
Germany, and speculation about the nature of displacement currents in the
elastic ether gradually died out... Regretfully, for many, the absence of
a conducting medium reduced electromagnetic theory from hard physical
concepts to abstract mathematical formulas unsupported by underlying
concrete examples. 'The grin is left but the cat is gone!'  It is a
perfect example of mathematical abstraction."

---------------------------------------------------
Now, as for equal rights, I continue to be egalitarian!  I agree that if
you put the antenna in a Faraday cage and only let the near M field out,
you'd still get an EM wave.  But I also _suspect_ that if you put the
antenna in a ferromagnetic shield that blocked the magnetic field, the
varying electric field could do the job by itself and would generate an
EM wave.

An aside:  Sometimes books that describe antenna operation focus on half
wave dipoles. They describe the special (quadrature) relationship between
current and voltage on this antenna, along with the locations of the
current and voltage nodes. The student is sometimes left with the
impression that you "need" this kind of standing wave arrangement to get
EM waves.  This is of course untrue:  Just look at radiation from a
terminated "traveling wave" antenna.  No standing waves, no I and E in
quadrature... but it radiates just fine.


Hope you and Tom and others and I can continue to discuss all this...

73   Bill





From [e-mail] Sun Apr 28 13:09:07 1996
From: [e-mail] (robert bowman)
Newsgroups: rec.radio.amateur.antenna
Subject: Re: Antenna Theory Question
Date: 26 Apr 1996 15:54:17 GMT
Message-ID: <4lqrj9$[e-mail]>
References: <4ljlm3$[e-mail]> <4lk8ou$[e-mail]>

In article <4lk8ou$[e-mail]>, [e-mail] (W8JI  Tom) say
s:
>One of the more sad things is separating the "waves" allows invention of
>antennas that just don't do what the inventor thinks they do. Insulated
>radials "work" on the principle of eliminating displacement currents with
>.025 inch of PVC, until a FS meter arrives on the scene.

aw, c'mon. using a FS meter and doing a few polar plots would take all
the fun out of building bigger, better antennas. anecdotal reports from
some lid who gives everyone a 599 are far more important.


From [e-mail] Sun Apr 28 13:09:08 1996
From: [e-mail] (Graham Seale)
Newsgroups: rec.radio.amateur.antenna
Subject: Re: Antenna Theory Question
Date: Sat, 27 Apr 1996 00:52:37 GMT
Distribution: world
Message-ID: <[e-mail]>
References: <4l80tb$[e-mail]> <4ld726$[e-mail]> <[e-mail]> <4lis67$[e-mail]>
Reply-To: [e-mail]

Hi there Moritz

In message <4lis67$[e-mail]>  you wrote:


(quoting me)

> >The way our "displacement currents" came about is not far removed from
> >the way Lavoisier conjured a "new" substance possessing "negative weight"
> >to explain the increase in weight of mercury as he drove off the
> >"Phlogiston" by heating.
>
> OK, but there is an important difference between a model that's simply
> wrong because it leeds to incorrect predictions and one that is right.

(Big smile!)

Yes Moritz.. I agree entirely -  if it leads to incorrect predictions.
The difficulty is - it didn't. If you make the weight of oxygen
(phlogiston) negative, and assume that it is "driven off" from the
metal instead of "aquired" to make the oxide - the predictions are
correct. This "experimental verification" was so pervasive, for so
many oxidising reactions that it aquired the same sort of respectability
that we currently accord to "displacement current", and it lasted
for many decades, and it engendered much hot debate, argument, rancour
and severed friendships.

I guess the point I was trying to make has some subtlties. I just do
not know which of our revered physical laws  - true as they are, come
with a mathematical baggage that will one day give way to more elgant
models. I had tried to cite a few to draw attention to the notion
that we are no more immune from "model worship" now than were our
forefathers.

73's G4WNT

--
Graham Seale



From [e-mail] Sun Apr 28 13:09:09 1996
Newsgroups: rec.radio.amateur.antenna
From: [e-mail] (Steve Ellington)
Subject: Re: Auto Tuner vs Multiband Vertical
Message-ID: <[e-mail]>
References: <[e-mail]> <4lgmjn$[e-mail]>
Date: Mon, 22 Apr 1996 19:22:38 GMT

: All of these problems can be resolved (or at least mediated) by using
: a center-fed antenna with a link-coupled tuner.

Wonder what the impedance limitations are on those biggggg baluns that
come with tuners? I know it's not necessary to present a 200 ohm Z to the
4:1 balun since the tuner compensates for what it sees on the other side
but how far can one deviate from the 200 ohms?

I see that Ameritron's big tuner has both a 4:1 and 1:1 balun built in.
This would seems to give a bit more flexiblility to match those lower Z
loads. For some reason, no one makes link coupled tuners any more nor were
they ever popular on the commercial market. WHY NOT? Maybe we should go
into business.





Steve Ellington [e-mail]  Louisville, Ky


From [e-mail] Sun Apr 28 13:09:10 1996
From: [e-mail] (WB3U)
Newsgroups: rec.radio.amateur.antenna
Subject: Re: Auto Tuner vs Multiband Vertical
Date: Mon, 22 Apr 96 17:17:36 GMT
Message-ID: <4lgmjn$[e-mail]>
References: <[e-mail]>

   [e-mail] (Dennis Mobley) wrote:

>What would work better & why:
>1. An auto tuner such as a SGC or ICOM connected to the end
>   of a 50 foot horizontal wire 20 feet high.
>2. A multi band vertical such as a Cushcraft R7000 or Gap Titan.
>
>Goals:
>1. 10 thru 40 meter coverage. (80m would be a plus)
>2. Max 100 watts transmitter.
>3. No ground radials do to other restrictions.
>4. Some what stealth. Limited wires to 50 feet and
>   verticals are OK. Fifty foot towers are not.
>
>Other information:
>       1. Urban city lots.
>       2. Terrain is very flat.

Dennis, the goals and description of the QTH point towards one
particular type of antenna:  A shortened horizontal dippole, center
fed with balanced line.  To drive this properly however, you will need
a means of switching feedline length on the various bands, or you will
need to use a balanced, link-coupled tuner like the Johnson Match Box.

My reasoning for this is:

1.  Verticals tend to be noisy in urban settings.
2.  Unless you can add considerably to the factory radial system,
    performance on 40M (and particularly 80M) will be mediocre at low
    mounting heights.
3.  Losses in the matching circuitry of the commercial verticals can
    be rather high.
4.  End-fed wires tend to create feedline radiation, shack RF and RFI
    unless the RF ground system is *very* good.
5.  A balun cannot be used to feed a non-resonant antenna (dipole) on
    all the bands unless a means is employed to control the load
    impedance seen by the balun.

All of these problems can be resolved (or at least mediated) by using
a center-fed antenna with a link-coupled tuner.

73,
Jack  WB3U

Post / CC by Mail


From [e-mail] Sun Apr 28 13:09:11 1996
From: [e-mail] (Rick Rikoski)
Newsgroups: rec.radio.amateur.antenna
Subject: Re: BCB-DXing
Date: Tue, 23 Apr 1996 17:29:00 -0400
Message-ID: <[e-mail]>
References: <[e-mail]>

In article <[e-mail]>, [e-mail] wrote:

> I'm posting my question here, because it sounds like this is where the
experts
> are.
> I am a broadcast band DX-er.
> I get the best results using a ( digital display ) auto radio, with a bench
> power supply.
> I realize that these radios are "tuned" to match a (30") whip antenna.

I don't know that these radios are "tuned" for a 30" whip but if you do go
much longer, you stand a good chance of overload if there are strong local
broadcasters in your area.

For openers, you might put up your long wire antenna and capacitor couple
it to your whip antenna.

Also use a tuned LC circuit, adjusting it for the clearest signal on the
frequency that you are trying to receive.

A grid dip meter, if you can find one, will be useful in determining the
correct design of the LC circuit. But it is not necessary.

--
Rick Rikoski
Chicago/Indiana Dunes
[e-mail]


From [e-mail] Sun Apr 28 13:09:12 1996
From: [e-mail]
Newsgroups: rec.radio.amateur.antenna
Subject: Beginner question
Date: 25 Apr 1996 18:34:48 GMT
Message-ID: <4logk8$[e-mail]>

I'm just starting to learn theory so be easy on me... :-)
I just don't understand the diagrams they show about attenna 'power' -
I guess they call this the lobe.  What determins the solid line?
Also is this supposed to be the view from above (below) the attenna or
from the side? The line seems to limit the signal - isn't the signal
radiating completely around the antenna? So what's the line - some
value to fit within the diagram?



From [e-mail] Sun Apr 28 13:09:14 1996
From: [e-mail] (Dale Chidester)
Newsgroups: rec.radio.amateur.antenna
Subject: Re: Beginner question
Date: 26 Apr 1996 11:52:53 GMT
Message-ID: <4lqdel$[e-mail]>
References: <4logk8$[e-mail]>
Reply-To: [e-mail]


In article [e-mail], [e-mail] writes:
>I'm just starting to learn theory so be easy on me... :-)
>I just don't understand the diagrams they show about attenna 'power' -
>I guess they call this the lobe.  What determins the solid line?
>Also is this supposed to be the view from above (below) the attenna or
>from the side? The line seems to limit the signal - isn't the signal
>radiating completely around the antenna? So what's the line - some
>value to fit within the diagram?
>


I assume you're referring to the field intensity patterns.  Think of the solid
 line
as a certain level of signal strength.  Inside the lobe would be higher, outsi
de
would be lower.  The point is it shows the pattern of radiation that a given t
ype
of antenna would produce, i.e., a dipole has two lobes to the sides and zilch
off
the ends.  The usual is to show the pattern as viewed from above.  Sometimes t
he
vertical pattern is plotted on the same set of axes as a dotted line.

The horizontal pattern is useful in determining how to lay out your antenna.
E.g.,
if you want to work stations primarily to the West of your location with a dip
ole,
you should orient the dipole North-South so the maximum side lobes lie in the
East-West direction.

The vertical pattern is important for skip.  As a rule, the lower the angle of
radiation the better for DX, since the signal has to bounce off one of the
ionized layers of the atmosphere.  A high angle (90 degrees is maximum) causes
 the
signal to bounce back almost to the same point it started.

Hope this helps.

        73,
                Dale

------------------------------------------------------------------------
Dale H. Chidester, PhD           N3HAL      "Against stupidity, even the
Cyanamid Agricultural Research Center        Gods in vain doth contend."
Process Development Facility                                    Schiller
PO Box 400,  Clarksville Rd.           Phone: [phone]
Princeton, NJ  08543-0400              Email: [e-mail]
------------------------------------------------------------------------




From [e-mail] Sun Apr 28 13:09:15 1996
From: Edward Lawrence <eal>
Newsgroups: rec.radio.amateur.antenna
Subject: Big DK-3: Screwdriver HF antenna
Date: 26 Apr 1996 23:49:17 GMT
Message-ID: <4lrndt$[e-mail]>

Who has a copy of the complete construction article?  I have mis-placed mine.
I will gladly send a SASE in order to obtain the articel  TNX.  WA5SWD



From [e-mail] Sun Apr 28 13:09:16 1996
Newsgroups: rec.radio.amateur.antenna
From: [e-mail] (Daniel Senie)
Subject: Re: Bird Strikes
Message-ID: <4lpies$[e-mail]>
References: <4l44j8$[e-mail]> <4lc6im$[e-mail]>
Date: Fri, 26 Apr 1996 04:12:12 GMT

In article <4lc6im$[e-mail]>,
robert bowman <[e-mail]> wrote:
>In article <4l44j8$[e-mail]>, [e-mail] (John N0ISL)
 says:
>>
>>The latest "hazard" to the enviornmet from hams is the potential injury to
>>endangered birds and other flying critters as they fly unknowingly into
>>towers or tower guy wires.
>
>
>the Ajo Amateur Radio Club (Ajo, AZ) had an article by a member who
>interacted with a Great Horned Owl while using a HamStick for mobile
>trolling. Since this occurred in the Organ Pipe National Monument, it
>was probably a federal offence.

I suppose that if the bird had been flying lower and hit the car's FM
broadcast antenna, it wouldn't have raised any eyebrows? At some point
there's not much that can be done...

As for birds interacting with ham towers, I guess I'd worry first about
such interactions with commercial towers which tend to be much taller.
I wonder if the birds notice those blinking beacons?

Dan



From [e-mail] Sun Apr 28 13:09:16 1996
From: [e-mail] (JAMES MCEWEN)
Newsgroups: rec.radio.amateur.antenna
Subject: Communications Quarterly
Date: 23 Apr 96 21:54:50 GMT
Message-ID: <[e-mail]>

     I've seen this pub referred to by several people ion the list,
     would someone please give me an address?  I think I want to see
     about a subscription.

     TIA

     Jim McEwen



From [e-mail] Sun Apr 28 13:09:17 1996
From: [e-mail]
Newsgroups: rec.radio.amateur.antenna
Subject: Re: DDRR
Date: 22 Apr 1996 16:56:20 -0700
Message-ID: <4lh6b4$[e-mail]>

In article <v01530500ad9f0028248e@[205.205.27.154]>, [e-mail] says...
>
>Where can I get information on Boyer's DDRR antenna?
>
>Thanks,
>
>Jean-Guy
>
>
Dear Jean-Guy,

If you understand a bit German, you might find "Antennenbuch" of Karl
Rothammel, Y21BK interseting to read.
It contains some pages on the DDRR-antenna with practical dimensions for
HF and VHF.

73 de Serge Stroobandt, G/ON4BAA


From [e-mail] Sun Apr 28 13:09:18 1996
From: [e-mail] (Graham Seale)
Newsgroups: rec.radio.amateur.antenna
Subject: Re: displacement current etc.
Date: Thu, 25 Apr 1996 00:54:20 GMT
Distribution: world
Message-ID: <[e-mail]>
References: <4ljr3n$[e-mail]>
Reply-To: [e-mail]

In message <4ljr3n$[e-mail]> Bill W0IYH wrote:

> >I occasionally wonder why other hams get enamored with the time derivative
> >of the displacement field being called the displacement current but
> >don't also get similarly enamored with the time derivative of the
> >magnetic flux density as a magnetization current.
>
>              L(di/dt) = NA(dB/dt) = V
>
> The basic law for zillions of devices with which we are all enamored.

Hi Bill

Probably because whenever we contrive a real di/dt in a nice hefty L
(say a transformer primary) as we disconnect the ohmmeter leads, we get
a nice fat reminder that leaves not the *slightest* doubt in the mind
it was a bit of genuine V!


Now to check out the time derivative of a "displacement vector" that
was thrown in as a mathematical artifice contrived to have the effect of:-

a) supplying a correction term to supplement a current density that
   came up short when a mathematical operation on it (divergence of
   current density) did not agree with the same quantity derived from the
   curl of a magnetic field (del.i = del.(del X H) --->0 )
                                 ~              ~
b) ceasing to have any value for static fields... ie.  d(D)/dt = 0
                                                         ~
....is entirely another matter.

Tee Hee - Tom and some friends are over in another thread driving
themselves nuts trying to create and measure this time derivative
of a mathematical analogue in a capacitor - and I dare not jest too
much because they are folk whose opinion I respect.

73 G4WNT

--
Graham Seale


From [e-mail] Sun Apr 28 13:09:19 1996
From: Cecil Moore <[e-mail]>
Newsgroups: rec.radio.amateur.antenna
Subject: Fiberglas Coil Forms
Date: 24 Apr 1996 17:19:38 GMT
Message-ID: <4llnra$[e-mail]>

What quality of mobile loading coil forms do hollow fiberglas rods make?
Could the diameter of a Hamstick simply be increased to get more inductance?

thanks & 73, Cecil, KG7BK, OOTC  (not speaking for my employer)




From [e-mail] Sun Apr 28 13:09:21 1996
From: [e-mail] (HSHK)
Newsgroups: rec.radio.amateur.antenna
Subject: Re: Field Day wire antenna hints needed
Date: Fri, 26 Apr 96 11:53:37 GMT
Message-ID: <4lqdp2$[e-mail]>
References: <[e-mail]>

In article <[e-mail]>, [e-mail] (Michael L. Ardai) w
rote:
>
>I was just given the task to fix up our Field Day antennas.  Right now,
>we have some "supposedly G5RV"s, made with deteriorating phone line
>soldered to some old RG8.  Unfortunately antennas aren't my strongpoint.
>We'll be putting up at least two, at right angles to each other, and
>I am looking for something multi-band.
>
>What would be the best wires to use for FD?  The ARRL antenna book
>describes a G5RV as a 102' center-fed dipole fed by ladder line...
>How long should the ladder line be?  Should I use a balun to connect it to
>the coax?  Just feed the antenna with the coax and leave off the ladderline?
>Run the ladder line all the way to the tuner?  (that won't work for the
>930 with built-in autotuner, but would work for the 130 with an MFJ tuner)
>
>Or is there something better that I should be looking at (other than
>stacked monobanders on a tower :-)
>
>Thanks and 73.

The last couple of years we have use 300 ft long wires with a
MFJ tunner and a 1/4 wave counter-poisefor each band we worked
and had much better results then when we had used verticals or
dipoles.

Bill  KA8VIT
á

-----BEGIN PGP PUBLIC KEY BLOCK-----
Version: 2.6.2

mQCNAzFNy7YAAAEEALR5cvCS1SKd5lMtslGug8IQ4nZQvk7zpKAWilqjrOGkmhuC
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6IBWYbT8vVOofRygf5AQl8ZTqw8UuwrlYoxTQ/4gW8c8PofbfwKJYZN00soxAAUR
tARIU0hL
=D/Ed
-----END PGP PUBLIC KEY BLOCK-----


From [e-mail] Sun Apr 28 13:09:22 1996
From: [e-mail] (Maurice Andries)
Newsgroups: rec.radio.amateur.antenna
Subject: Force 12 info please
Date: Thu, 25 Apr 1996 16:45:50 GMT
Message-ID: <4loa4c$[e-mail]>

Hi all,

A non-connected friend of mine would like info about the Force 12 antennas
type: 5BA and 4BA.
If you have this info or have such an antenna, I would like to know what you
think of it. How does it perform??

Thanks a lot for answering (pefer e-mail).


Just my 2 cents, Your mileage may vary
Opinions are my own (most of the time).

73 de Maurice, [e-mail] (internet)
               ON4BAM@ON6AR.#AN.BEL.EU
               http://user.glo.be/~mauricea (Ham links and station info)




From [e-mail] Sun Apr 28 13:09:23 1996
From: [e-mail] (Rob Whitacre)
Newsgroups: rec.radio.amateur.antenna
Subject: Re: Free RF Software
Date: 23 Apr 1996 12:00:48 GMT
Message-ID: <4ligpg$[e-mail]>
References: <[e-mail]> <4lecoq$[e-mail]>

In article <4lecoq$[e-mail]>, Dilbert says...
>
>If someone gets this will they please post it here
>
>I am unable to access it.
>
>thanks
>
The new URL works fine, and so does the program...

Rob WB8WQA



From [e-mail] Sun Apr 28 13:09:24 1996
From: "mark.n.hougaard" <[e-mail]>
Newsgroups: rec.radio.amateur.antenna
Subject: Re: Free RF Software
Date: Tue, 23 Apr 1996 17:44:13 -0500
Message-ID: <[e-mail]>
References: <[e-mail]>
To: Max Froding <[e-mail]>

Max Froding wrote:
>
> located at-->   http://www.users/aol.com/maxfro/private/
>
>                                 TuneKit for Windows
>
>         Filter Tuning Kit for Windows is a Electronic Filter Synthesis

Please repost this URL.  This address is still not listed in the DNS.

Thanks

Mark

====================================================================
| Mark N. Hougaard  (KB9FCC)            Lucent Technologies        |
| Location: ILL650  Room: 1Q-305        1000 East Warrenville Road |
| Work Phone:  [phone]           Post Office Box 3013       |
| E-mail:  [e-mail]        Naperville, IL  60566-7013 |
====================================================================
You can change without growing, but you can't grow without changing.


From [e-mail] Sun Apr 28 13:09:26 1996
Newsgroups: rec.radio.amateur.antenna
From: Howard Rensin <[e-mail]>
Subject: Re: Free RF Software
To: Max Froding <[e-mail]>
Message-ID: <[e-mail]>
References: <[e-mail]>
Date: Mon, 22 Apr 1996 01:10:47 GMT

Max Froding wrote:
>
> located at-->   http://www.users/aol.com/maxfro/private/
>
>                                 TuneKit for Windows
>
>         Filter Tuning Kit for Windows is a Electronic Filter Synthesis
>         program and a practical filter tuning aid for actually designing
>         and building a working filter. TuneKit is a small window module
>         with some powerful features that include;
>
>     1.) Chebyshev Lowpass and Highpass Filter Synthesis from 2 to 25
>         poles.
>
>     2.) Narrow bandpass Chebyshev Inductive or Capacitive Coupled Filters
>         from 2 to 8 poles.
>
>     3.) Bridged-T Notch Filters, provides rejection of 60dB or more with
>         practical values of inductor Q, using only 4 components.
>
>     4.) The Filter Data will be saved in ARRL Radio Designer 1.0 format
>         for instant Analysis of your design. TuneKit was designed to be
>         used as a front end for ARRL Radio Designer, There is a Stay on
>         Top Option button for repetitive filter designing while using ARRL.
>         (So, now you can Design and Analysis in seconds.)
>
>     5.) Calculates Air Core Coil Windings for a desired Inductance.
>
>     6.) Find the Actual Values of Inductors or Capacitors to use in your
>        filter's tank circuits, using the Resonant Frequency Calculator
>        and then save the values in the tunekit.ini file for instant recall.
>
>     7.) Fast access to the Window's Calculator, so you don't have to hunt
>         around your desktop. Opens as many as you want.
>
>     8.) Help Status Bar for On Line help of any Control in the Module.
>         Just press and hold and the status bar reveals the function.
>
>         That's most of the features in this version, future versions will
>         include Cauer Elliptical, Bessel, Linear Phase, Gaussian, Microstrip
>         Combline, Cavity Tuned, Interdigital, and etc. in module form.
>         Hope you find TuneKit useful as part of your Filter Tool Kit.
>
>     located at-->   http://www.users/aol.com/maxfro/private/
>

PLEASE REPOST THIS URL. THIS ADDRESS IS NOT LISTED IN THE DNS.
           Howard

--
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Howard M. Rensin KC3D         'A man and his cigar are never parted'
15221 Centergate Dr.
Silver Spring,MD.,20905         [e-mail]
 PGP Key available at any Key Server ( use 2047 bit version).
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~


From [e-mail] Sun Apr 28 13:09:27 1996
From: [e-mail] (Joe Pardue)
Newsgroups: rec.radio.amateur.antenna
Subject: Re: Free RF Software
Date: Wed, 24 Apr 96 17:32:00 GMT
Message-ID: <4lloig$[e-mail]>
References: <[e-mail]> <4lecoq$[e-mail]>
To: Dilbert

>If someone gets this will they please post it here
>I am unable to access it.
>
>Dilbert

I e-mailed Max asking for a correction to the URL and he offered me the
following corrected one:

http://members.aol.com/maxfro/private/tunekit2.html

which is valid.

JoeP




From [e-mail] Sun Apr 28 13:09:28 1996
From: Dilbert
Newsgroups: rec.radio.amateur.antenna
Subject: Re: Free RF Software
Date: Mon, 22 Apr 1996 01:24:32 GMT
Message-ID: <4lecoq$[e-mail]>
References: <[e-mail]>

If someone gets this will they please post it here

I am unable to access it.

thanks



From [e-mail] Sun Apr 28 13:09:28 1996
From: [e-mail]
Newsgroups: rec.radio.amateur.antenna
Subject: Gap Voyager
Date: 22 Apr 1996 18:46:51 GMT
Message-ID: <4lgk6r$[e-mail]>

Comments on this antennas performance as a contest antenna on 80 and 160
would be much appreciated.  How is it's performance vs. an inverted L with
vertical portion less than 70 feet?  Thanks.  Please reply directly.

Al, KE6BER/1, [e-mail]



From [e-mail] Sun Apr 28 13:09:29 1996
From: Rich Fortnum <[e-mail]>
Newsgroups: rec.radio.amateur.antenna
Subject: Great Commercial Omnidirectionals?
Date: Fri, 26 Apr 1996 17:24:08 -0400
Message-ID: <[e-mail]>
Reply-To: [e-mail]

Anybody know of any great multiband omnidirectional antenna's?  =

Perhaps around 100 watts.

Cheers.
-- =


Rich Fortnum (aka BeeRich)
F&M Breweries
Guelph, Ontario
[e-mail] / http://www.pints.com/pints/index.html
Renaissance Brewers of Fine Ales and Lagers=99
VA3 RFZ


From [e-mail] Sun Apr 28 13:09:30 1996
From: Rich Fortnum <[e-mail]>
Newsgroups: rec.radio.amateur.antenna,rec.radio.amateur.equipment
Subject: Great Commercial Omnidirectionals?
Date: Fri, 26 Apr 1996 17:25:12 -0400
Message-ID: <[e-mail]>
Reply-To: [e-mail]

Anybody know of any great multiband omnidirectional antenna's?  =

Perhaps around 100 watts.

Cheers.
-- =


Rich Fortnum (aka BeeRich)
F&M Breweries
Guelph, Ontario
[e-mail] / http://www.pints.com/pints/index.html
Renaissance Brewers of Fine Ales and Lagers=99
VA3 RFZ


From [e-mail] Sun Apr 28 13:09:32 1996
From: [e-mail] (W8JI  Tom)
Newsgroups: rec.radio.amateur.antenna
Subject: Re: Hamsticks as a beam?
Date: 23 Apr 1996 07:21:26 -0400
Message-ID: <4liefm$[e-mail]>
References: <[e-mail]>

In article <[e-mail]>, Zack Clobes
<[e-mail]> writes:

>
>While reading through some messages on the newsgroup, I got an idea about
>Hamsticks..   Has anyone tried
>combining a couple of "dipoles" to form a parasitic array?  I realize the
>matching might be a bit tricky but
>would I not be right in saying that you could cut the wind loading and
>rotator requirements way down?

Hi Zack,

When a directive pattern is formed by cancelling the radiation in other
directions the radiation resistance drops. That increases the loss in the
already lossy antenna element made from Hamsticks.

Efficiency may be so bad you have no net gain over a simple Hamstick
dipole, and that already is loss over a regular dipole.

A second problem is mutual coupling is reduced. Mutual coupling is what
excites the second element in a parasitic element beam antenna. When it is
reduced, it becomes harder to get directivity in a parasitic element beam
antenna.

You could try it as an experiment, but those are the two main
difficulties. I expect (just a guess) it wouldn't work well if at all
below 15 or 20 meters.

73 Tom


From [e-mail] Sun Apr 28 13:09:33 1996
Newsgroups: rec.radio.amateur.antenna
From: [e-mail] (Joe Mack)
Subject: Re: Help - Help- Could glass mount ant. blow up HT???
Message-ID: <[e-mail]>
References: <4lditi$[e-mail]> <4le18m$[e-mail]>
Date: Wed, 24 Apr 1996 14:23:09 GMT

In article <4le18m$[e-mail]> [e-mail] (WB
3U) writes:
>   [e-mail] (KE6JSS) wrote:
>
>>After a couple of radio checks - a good 50mi + at 1 Watt, the radio
>>went dead.  Not completely, just mostly.  The radio will TX, as my
>>scanner proves.

The scanner just shows it is generating a few mw. You need a power
meter (get a 2 needle SWR meter and leave it in line, it will
save you a lot of grief in situations like this). Most modern
HTs can operate into a short or open circuit (like if you leave
the rubber ducky off) without harm.

It just cant key up a repeater, nor does it display
>>a signal strength (at all).

THe symptoms are the same as if you didn't have an antenna. Is your
co-ax OK? My rig died this way once and it was because the wire
from the BNC connector to the radio inside had broken.

        You should be able to hit something with a rubber duck.

        Joe NA3T
        [e-mail]


I have tried nearly all of my ant's.
>>Please, help me. The radio is under warrenty.  Did the tint cause
>>this?  Why and how? Reflected/Absorbed energy.
>
>What's the SWR?
>
>73,
>Jack  WB3U




From [e-mail] Sun Apr 28 13:09:34 1996
From: [e-mail] (Peter Frenning)
Newsgroups: rec.radio.amateur.antenna
Subject: Re: Help with cellular antenna
Date: Tue, 23 Apr 1996 07:48:54 GMT
Message-ID: <4li216$[e-mail]>
References: <4l8d73$[e-mail]> <4lfvml$[e-mail]>
Reply-To: [e-mail]

[e-mail] (Rob Whitacre) wrote:

>In article <4l8d73$[e-mail]>, [e-mail] says...
>>
>>Acknowledging that this is not strictly an amateur radio problem, I would
>>still like to ask for help with the following problem:
>>
>>I need to buy/build a highly directional antenna for the cellular telephone
>>band.  I've built Yagi arrays for VHF, seen it done for UHF, but I've never
>>considered anything like the cellular band.  Can anyone point me to
>>a commercially available antenna I might use, modify, or copy?  What about
>>equipment to tune the antenna once I'm done?  Any common mistakes that I
>>might avoid?
>>
>>For the curious, the situation is this: a friend is moving to a city
>>just outside the local calling area for the cellular company that serves
>>her family's home town.  If the antenna is sufficiently directional, I think
>>she could hit the local cellular company's tower rather than the tower
>>that serves her new home.  Since she's pretty close to her family, the
>>savings in her phone bills would justify the expense even if we needed
>>a commercial antenna or a meter that would enable me to build one for her.
>>
>>Thanks!
>>
>>--Cliff (N5TJU)
>>

>Cliff,

>Cushcraft/Signals advertises "6, 9, 11, & 13 dBd models", yagis for 800 MHz.

>For a simple directional antenna that you could build, consider making a
>corner reflector antenna and using the antenna from a transportable phone
>for the active element.

>73,
>Rob WB8WQA

I've heard about people using homebuilt HB9CV antennas for 900 MHz Cellular
phones with amazing results - over twice the range of the built-in mini
whip.

An HB9CV for this band is very small, light weight and easy to build and
tune. Gain is about 4-5 dB over a dipole.

73
/peter
(Soon to be licensed for VHF & UHF)    :-)

******************************************************************************
**
Peter Frenning, UNIX Product Mgr., Siemens-Nixdorf DK, Ph.: [phone]
Snailmail: Dybendalsvaenget 3, 2630 Taastrup, Denmark, Fax: [phone]
Email: [e-mail](...!dkuug!sni.dk!pef)(NERV: pfrenning.cph)
X400:C=DK; A=400NET; P=SCN; O=SNI; S=Frenning; G=Peter; OU1=CPH1; OU2=CC
       Private connection: [e-mail]
************  Come visit us on the web; URL http://www.sni.dk  ***************
**



From [e-mail] Sun Apr 28 13:09:35 1996
From: [e-mail] (CHARLES J. MICHAELS)
Newsgroups: rec.radio.amateur.antenna
Subject: Re: HELP! **** Calculating Beam Heading
Date: 21 Apr 1996 14:45:30 GMT
Message-ID: <4ldhma$[e-mail]>


Pat wants to calculate beam bearings from latitude and longitude
of two points on earth.

You need two equations:
(1)   cos D = sinA sinB + cosA cosB cos L

                           sin B - sinA cos D
(2)   cos C =       -----------------------------
                             cos A sin D

Where
A = your latitude in degrees
B = latitude of the other location in degrees
L = your longitude minus that of the other location (algebraic)
D = distance along path in degrees of arc
C = true bearing from north if the value foe sin L is positive.
If sin L is negative, true bearing is 360 - C

Use equation (1) to determine angular value for D
From this value the path-length distance may be determined.
Use equation (2) to determine bearing angle.

Example case
A = 37.7 degrees,  B = -32 degrees,
L = 98.7 - (-115.9) = 214.6
From Eq (1) cos D = sin 37.7 sin (-32) + cos 37.7 cos (-32)
cos 214.6.   therefore D = 151.21 degrees of arc
and at 60 nautical miles per degree = 60 x 151.21 = 9073
nautical miles.
To convert to statute miles multiply by 69.041
69.041 x 151.21 = 10,440 statute miles.
From Eq (2) substituting the similar parameters C = 89.1 but
because the sin of L (214.6 degrees) is negative,  the correct
value is 260 - 89.1 = 270.9 degrees true.

Easiest way is to write it up as a BASIC program.

Charlie, W7XC
--


From [e-mail] Sun Apr 28 13:09:37 1996
Newsgroups: rec.radio.amateur.antenna
From: Monty Wilson <[e-mail]>
Subject: Re: Help: 6m Dipole Ant
Message-ID: <[e-mail]>
Date: Fri, 26 Apr 1996 13:57:06 GMT
References: <4lp20o$[e-mail]>

[e-mail] wrote:
>How long would the two individuals legs need to be for a 6m centerfed
>dipole om 50.125 mhz?
>

Start with 4'8" for each leg and shorten them to bring it into
resonance.  You shouldn't have to remove much.  Most HF SWR
bridges will cover 6m well enough to find resonance, though they
may not give accurate SWR readings.

--
.........Monty.
[e-mail]




From [e-mail] Sun Apr 28 13:09:38 1996
From: [e-mail] (MREISING)
Newsgroups: rec.radio.amateur.antenna
Subject: Re: HF Antennas for RV's?
Date: 23 Apr 1996 07:50:16 -0400
Message-ID: <4lig5o$[e-mail]>
References: <4lfugn$[e-mail]>
Reply-To: [e-mail] (MREISING)

I use an SGC tuner with a helical wound antenna on my truck.  I can run
the feed into the trailer and use the rig there.  Also check out the ARRL
antenna book.  There is a plan for mounting a modified Hustler 5BTV
trapped vertical on a foldover mast made from Unistrut and mounted to the
rear bumper of the trailer.  It looks to be a substantial design with the
ability to quickly raise or lower the antenna.

73 de Mark, WB9BVV


From [e-mail] Sun Apr 28 13:09:39 1996
From: [e-mail] (Cecil A. Moore~)
Newsgroups: rec.radio.amateur.antenna
Subject: Re: HF Antennas for RV's?
Date: 24 Apr 1996 16:34:43 GMT
Distribution: world
Message-ID: <4lll73$[e-mail]>
References: <4lfugn$[e-mail]> <4lhn75$[e-mail]>

In article <4lhn75$[e-mail]>,
Gerald Schmitt  <[e-mail]> wrote:

>In my best Rod Serling voice: Consider the following. A small
>tuner, a slingshot, a fishing reel, a couple of baluns and a
>quarter mile roll of electric fence wire and a tape measure,
>Works great and very very cheap.

Wouldn't work around here. Cactus and Palo Verde trees don't
grow tall enough. 73, Cecil, KG7BK, OOTC


From [e-mail] Sun Apr 28 13:09:40 1996
From: [e-mail] (MREISING)
Newsgroups: rec.radio.amateur.antenna
Subject: Re: HF Antennas for RV's?
Date: 25 Apr 1996 08:08:06 -0400
Message-ID: <4lnpv6$[e-mail]>
References: <4lm88k$[e-mail]>
Reply-To: [e-mail] (MREISING)

> >trapped vertical on a foldover mast made from Unistrut and mounted to
the
>>rear bumper of the trailer.

>Hi Mark, I would recommend that he get the feedpoint as high as possible.
>The top of an RV is a superior mounting position to the bumper.

>73, Cecil, KG7BK, OOTC  (not speaking for my employer)

The antenna feed point in this design is above the top of the RV.  The
fold over portion of the mast is at the roof level, with the stationary
portion attaching to the bumper of the RV approximately seven feet below.
I believe the reason the bumper was selected is because it is strong
enough to support the antenna, while a roof mount would not (many RVs and
trailers are constructed of thin wood and aluminum sheet).  The mast is
braced to the roof just below the hinge.

73 de Mark, WB9BVV


From [e-mail] Sun Apr 28 13:09:41 1996
From: [e-mail] (JAMES MCEWEN)
Newsgroups: rec.radio.amateur.antenna
Subject: Humor:  You might be a ham if...
Date: 23 Apr 96 20:44:55 GMT
Message-ID: <[e-mail]>




You might be a ham if:

If you window shop at Radio Shack
If you introduce your wife as "[e-mail]"
If you want an 8X CD-ROM for Christmas
If the only jokes you receive are through e-mail
If you use a CAD package to design your son's Pine Wood Derby car
If you have used coat hangers and duct tape for something other than hanging
coats and taping ducts
If, at Christmas, it goes without saying that you will be the one to find the
burnt-out bulb in the string
If your ideal evening consists of fast-forwarding through the latest sci-fi
movie looking for technical inaccuracies
If you carry on a one-hour debate over the expected results of a test that
actually takes five minutes to run
If you have modified your can opener to be microprocessor driven
If you know the direction the water swirls when you flush
If you have ever taken the back off your TV just to see what's inside
If a team of you and your coworkers have set out to modify the antenna
on the radio in your work area for better reception
If you thought the concoction ET used to phone home was stupid
If you have never backed-up your hard drive
If you have ever saved the power cord from a broken appliance
If you have ever purchased an electronic appliance "as-is"
If you see a good design and still have to change it
If the salespeople at Circuit City can't answer any of your questions
If you still own a slide rule and you know how to work it
If you have more toys than your kids
If you have a habit of destroying things in order to see how they work
If the microphone at a meeting doesn't work and you rush up to fix it.
If you can remember 7 computer passwords but not your anniversary
If you have ever owned a calculator without an equal key
If you did the sound system for your senior prom
If your girlfriend says the way you dress is no reflection on her
If your wristwatch has more buttons than a telephone
If you have more friends on the Internet than in real life
If you thought the real heroes of "Apollo 13" were the mission controllers
If you think your computer looks better without the cover
If your wife hasn't the foggiest idea what you do at work
If you know what http:/ stands for
If you've ever tried to repair a $5.00 radio
If your favorite part of the 6 o clock news is comparing their latest satellit
e
weather picture with yours
If your three year old son asks why the sky is blue and you try to explain
atmospheric absorption theory




From [e-mail] Sun Apr 28 13:09:42 1996
From: [e-mail] (Ross Alexander)
Newsgroups: rec.radio.amateur.antenna
Subject: Re: Humor: You might be a ham if...
Date: 25 Apr 1996 14:39:40 GMT
Message-ID: <4lo2rc$[e-mail]>
References: <[e-mail]>

[e-mail] (JAMES MCEWEN) writes:

> You might be a ham if:
> [...]
> If you have ever owned a calculator without an equal key
> [...]

Isn't that a canonical computer nerd list?  I know more than a few
nerds who don't know what a radio was; they'd pick up the key and
try to use it as a mouse.

BTW, I don't know that I've ever owned a calculator that did have an
equal key :).

regards,
Ross ve6pdq
--
Ross Alexander, ve6pdq  --  [phone]  --  [e-mail]


From [e-mail] Sun Apr 28 13:09:44 1996
From: [e-mail] (C319Chris)
Newsgroups: rec.radio.amateur.antenna
Subject: Re: indoor am antenna question
Date: 19 Apr 1996 05:43:55 -0400
Message-ID: <4l7n8r$[e-mail]>
References: <4k9bpc$[e-mail]>
Reply-To: [e-mail] (C319Chris)

"I have constructed an am antenna out of a coiled piece of wire with about
two feet of uncoiled wire on each end for maneuverablity, and attached
the ends to the two am antenna terminals on my stereo.
Is this single coiled
wire the best bet for an indoor am antenna, and how do the length of
the wire, the diameter of the coil and the length of the non-coiled part
of the wire affect, if at all, the reception? I am aiming primarily to
recieve a broadcast on 770 am."

You have constructed an untuned loop.  The output of an untuned loop is
dependent upon the area of the loop, the number of turns in the loop, and
the angle of arrival of the signal.  Loop antennas have a figure-8 pattern
with nulls broadside to the loop.  In other words, if you rotate the loop
so that the "circular" part faces the broadcasting station, pickup of that
station will be diminished.  If you can determine the direction of the
station using the antenna's null, then rotate the antenna another 90
degrees, you will have optimized the orientation of the antenna.  The
turns of the coil should "point" toward the transmitter, if that makes
sense.  The short wires used to connect it to your stereo probably don't
have an appreciable effect on its performance.

Whether it is the best bet depends on whether you are happy with your
reception of 770.  If you are, it probably is the best bet since you built
it for a few pennies' worth of wire and don't have to mess with tuning.
If you need more "oomph", try adding more or larger turns.  If that still
isn't enough, or your receiver has trouble dealing with a strong nearby
station,  perhaps a tuned loop should be considered.


From [e-mail] Sun Apr 28 13:09:45 1996
From: [e-mail] (Gary V. Deutschmann, Sr.)
Newsgroups: rec.radio.amateur.antenna
Subject: Re: Inexpensive Antenna Rotors?
Date: Thu, 25 Apr 1996 17:06:58 GMT
Message-ID: <4lobjg$[e-mail]>
References: <[e-mail]> <[e-mail]> <[e-mail]> <4lk5e2$[e-mail]>

Greg Limeberry <[e-mail]> wrote:

>Jim:

>The only thing I would feel safe rotating with a Radio Shack rotor might
>be a hot dog in my gas grill. Anything beyond that, the risk is yours.
>Hopes this helps!

>Greg


Has anyone ever thought of mechanical rotors?

In my last home, I had one yagi that came through the roof and could
be turned at the ceiling from within the shack.  However, the most
interesting mechanical rotor, was one that used a section of sewer
snake cable that ran from the tower pipe (ratateable with thrust
washers) right into the shack.  A large T-Handle on the end of the
cable and a map pasted on the wall was all it took to have a rotor
that never burned out, or broke.....

TTUL - 73+ de Gary - KG0ZP





From [e-mail] Sun Apr 28 13:09:46 1996
From: [e-mail](Ted Viens )
Newsgroups: rec.radio.amateur.antenna
Subject: Re: Inexpensive Antenna Rotors?
Date: 24 Apr 1996 20:05:20 GMT
Message-ID: <4lm1i0$[e-mail]>
References: <[e-mail]> <[e-mail]> <[e-mail]> <4lk5e2$[e-mail]>

Hmmm...  Let's see now...  I have the cheapy Radio Shack rotor on a ten
foot mast with a ten foot mast sticking out the top of it with the
biggest darn UHF/VHF TV antenna RS sells about a foot above the rotor
and one of those four foot scanner sticks at the top at twenty feet.
The support mast is held by their shorty tripod fastened to a half
sheet of plywood weighted down with three five gallon roof tar cans
filled with odd mixes of roof tar and rain water.  It survived all but
the worse wind storm of nighty five when it got knocked off the roof
onto the ground.  Several months later when I finally decided to put it
back on the roof, I made a passing attempt to straighten the mast
sections, straightened the VHF elements that would straighten and broke
off those that wouldn't, reattached the UHF section to the VHF section,
bolted the tripod to the plywood, and replaced one of the rusty cans of
roof tar and rain water with an 80 pound sack of pre-mix.  I rewired
the rotor, Tightened up all the clamps on the rotor and tripod and the
darn thing worked.  Although I don't rotate often, it was still
rotating last night.  And it has survived all of the windstorms since
being put back up.  We had tornadoes only ten miles from here two days
ago.  (all be it, small ones...)

Now, if I remember rightly, I bought it for 40 dollars on sale.  In my
way of thinking, it may not be a Yaesu, but it rates right up there in
the price/performance figuring...

In <4lk5e2$[e-mail]> Greg Limeberry
<[e-mail]> writes:
>
>Jim:
>
>The only thing I would feel safe rotating with a Radio Shack rotor
might
>be a hot dog in my gas grill. Anything beyond that, the risk is yours.

>Hopes this helps!
>
>Greg
>

--
Bye...  Ted..
Deep in the Heart of the Armpits of Houston, Texas...


From [e-mail] Sun Apr 28 13:09:48 1996
From: Rich Fortnum <[e-mail]>
Newsgroups: rec.radio.amateur.antenna
Subject: Re: J-Pole Gain (Was Re: Tuning a copper J-Pole.)
Date: Fri, 26 Apr 1996 17:34:47 -0400
Message-ID: <[e-mail]>
References: <4l8mtp$[e-mail]> <4lga1s$[e-mail]> <4li9co$[e-mail]> <4lk4gc$[e-mail]>
Reply-To: [e-mail]
To: Paul Cordingley <[e-mail]>

Paul Cordingley wrote:
> =

> [e-mail] () wrote:
> =

> >>    King, Mimno and Wing, "Transmission Lines, Antennas and Wave Guides=
,"
> >>    originally published by McGraw-Hill in 1945, republished by Dover
> >>    in 1965.  SBN: 486-61343-7
> =

> >This book shows two important things about j-poles, which some folks
> >prefer not to believe:
> =

> >1) the j-pole is not a simple sure-fire antenna and a good beginner's
> >   project.
> =

> I haven't read the text, and your double negative may have confused
> me, but I'd still say the J-pole is a good project for learners. It
> uses basic materials that are fairly easy to work with (hence
> encouraging the novice to experiment), it will tolerate corrections to
> a poor first attempt (cut the dimensions wrong? tear it apart, trim,
> and reassemble), it's sturdy, and it has a number of features which
> are thought-provoking to the beginner ("gee, why isn't the antenna
> just acting as a short-circuit across the coax?"). When you do get it
> right, it works well.

Amen.  Cheers for the good notes.  I made a J-Pole, and I push 5.5 watts th=
rough RG-58, about 70 feet =

no less.  I get out over most of the area I need, through my little dual ba=
nd handheld!  It's about 27 feet =

above the ground, and it works like a charm.  I modified my design by not s=
oldering, but using stainless =

steel clamps to attach both sides, so that manipulation is quite easy.  Can=
't wait for HF now.  I love =

soldering, but I can't find enough to solder.  Beams would do amazing work,=
 using more power, =

especially with those tiny VHF/UHF beams.  I couldn't agree with you more. =
 I have never soldered, =

and I own a brewery.  Now, I look forward to working that type of thing!  I=
 agree with the promotion of =

the hobby, and trying new things.  Soldering alone is quite fun, at least f=
or me.  =


> IMHO the problem arises when the design is written up in a
> paint-by-numbers format without explaining the finer points.

I agree.  I have a J-pole that I have made, and it works great.  I don't kn=
ow how it works though.  =

Apparently the base can be as long as I want, but that goes against what I =
believe to be resonance =

theory.  I don't get it.  The cactus double J-pole has better understanding=
 behind it, as it's a segregated =

unit, and the whole thing can resonate as a single unit.  =


> Here's a tip for the comments about isolating the base: I mounted my
> j-pole in a base made from white PVC pipe. Cut a piece of piping in
> half lengthwise and set the base in it, slide a T-filling over one
> element, then connect these with an L-fitting and another short piece
> of PVC pipe. Use epoxy to make the whole assembly rigid. Now you have
> a 'handle'- use a little more PVC piping to stand the antenna away
> from any nearby metal.

What we need is a cheap single rod (PVC or otherwise) to lift a simple ligh=
t j-pole type of antenna =

without getting a tower.  My roof is about 22 feet (industrial) and I have =
some copper pipe holding it =

higher.  I don't need a tower for a j-pole, and I think I can use guy-wires=
=2E  =


Whaddya think?

Cheers.

-- =


Rich Fortnum (aka BeeRich)
F&M Breweries
Guelph, Ontario
[e-mail] / http://www.pints.com/pints/index.html
Renaissance Brewers of Fine Ales and Lagers=99
VA3 RFZ


From [e-mail] Sun Apr 28 13:09:49 1996
From: [e-mail] (Raymond Sarrio)
Newsgroups: rec.radio.amateur.antenna
Subject: Large Ham Classified database->http://www.csz.com/sarrio.html
Date: Mon, 22 Apr 1996 07:59:35 -0700
Message-ID: <[e-mail]>

The Raymond Sarrio Company's Ham Radio WWW site is proud to announce a
FREE Ham Radio classified advertising page at

http://www.csz.com/sarrio.html.

This new classified section will include
Hams to search for equipement with the help of a search engine--no need to
scroll through 100's of listing before you find that special piece of
gear. Plus, when you find the gear your interested in, each listing comes
with point-and-click e-mail access direct to the Ham that listed the item.


For those Hams with gear to sell, take note! It is absolutely FREE to list
your equipment within the Ham Classifieds, and there will be no posting
time delays.Your posting will go on-line, in our classified search
engine,in about 1 hour. All you need do is fill out a simple forms page, and
upon its (point-and-click) submission, your "For Sale" advertisement is
on-line.

I will be purging the classified listing initially about once every month,
but that timeline will shorten as our classified numbers go up. Give it a
try, and let me know how you like it. 73's Ray
--
The Raymond Sarrio Co. a full feature Ham Radio Storefront on tth WWW at http:
//www.csz.com/sarrio in association with Brillar Enterprises http://win-win.co
m/brillar an Extensive Discount CD-Rom Catalog!



From [e-mail] Sun Apr 28 13:09:50 1996
From: Ty Stober <[e-mail]>
Newsgroups: rec.radio.amateur.antenna
Subject: Larsen Fixes 2/70 problem identified by user
Date: Fri, 26 Apr 1996 14:09:54 -0700
Message-ID: <[e-mail]>

Several weeks ago, an article was posted identifying a problem Larsen
had with its NMO 2/70 B black open coil dual band whip.  The posting
caused a corrective action request to be generated by Larsen's quality
system.  The problem has now been corrected.

Larsen is very appreciative of the feedback given by its loyal
customers.  We are constantly looking for ways to improve our products
and our product offerings.  The input received by you, the user, is very
important.

If you every have a problem or suggestion, feel free to e-mail.  The
e-mail account is [e-mail].


From [e-mail] Sun Apr 28 13:09:52 1996
From: Ty Stober <[e-mail]>
Newsgroups: rec.radio.amateur.antenna
Subject: Larsen Fixes 2/70 problem identified by user
Date: Fri, 26 Apr 1996 14:09:06 -0700
Message-ID: <[e-mail]>

Several weeks ago, an article was posted identifying a problem Larsen
had with its NMO 2/70 B black open coil dual band whip.  The posting
caused a corrective action request to be generated by Larsen's quality
system.  The problem has now been corrected.

Larsen is very appreciative of the feedback given by its loyal
customers.  We are constantly looking for ways to improve our products
and our product offerings.  The input received by you, the user, is very
important.

If you every have a problem or suggestion, feel free to e-mail.  The
e-mail account is [e-mail].


From [e-mail] Sun Apr 28 13:09:53 1996
From: [e-mail]
Newsgroups: rec.radio.amateur.antenna
Subject: Magnectic Small Loops...RE:
Date: 23 Apr 96 17:51:37 GMT
Message-ID: <[e-mail]>

Hi Tom. Thanks for the advises!
There's some final comments...
1) Everythigh all right concerning the mechanical cares to avoid losses.
This was more or less checked with a 8 side octagon using a Antenna
Modelling Software.

>That "electrical shield" does absolutely nothing at all to improve
balance
>or E field coupling.  Do not worry about it.

>It can improve matching over wide frequency ranges because the broken
>shield and cable acts like a L network at the higher bands.

See, in my case, I don't have a nice place to antenna mount. Maximum abt
3 meter high, so vy close to all domestic electrical wiring. What I saw
here's that using the shielded loop the "standard" electric noise
(shavers, brushes motors, and so on) was reduced, if I consider my
reference a 1/4 wavelenght vertical ground plane. But the description of
the "L" network clear some matching problems.
   In fact, the 14...30 option was done and with good results. I don't re
member, but may be I started "cut and trying" the shielded loop at the
highest work frequency.
   Now I'm checking a 6 meter model, using the largest loop I can, where
largest means the size that still requiring a small "C" at the radiating
loop (5 to 8 pf) that, according with your experiences, will be the
"maximum efficiency arrange" - the 10 meter efficiency(-1dB).

>A dipole will always be better for signal, but not much better. My 3 foot
>loop is one dB down from a dipole on ten meters, and 6 dB down on 10 MHz.
   I agree, but depends on the site they're assembled. My case, for insta
nce, where there's not too much room, a 20/40 trapped dipole in a
inverted-vee assembly has its ends close to the ceiling - .5 meter or so.
The ressonance falls to 6.45MHz at 40 meter. The radiating pattern's good
enough to local (1000Km) range. I think a loop at the same 5 meter hight
will have at least the same results and, if well matched, low
transmission line losses.
Thanks again for the help. 73.
Marcus Ramos - [e-mail] - Sao Paulo - Brasil


From [e-mail] Sun Apr 28 13:09:54 1996
From: (Gary) [e-mail]
Newsgroups: rec.radio.amateur.antenna
Subject: Re: Mobile Antenna
Date: 23 Apr 1996 18:58:55 GMT
Message-ID: <4lj99f$[e-mail]>
References: <[e-mail]>

>   Murray Harris <[e-mail]> writes:
>  What is the best HF mobile antenna?  I plan to mount it on the back
>  of a Toyota Land Cruiser.  Opinions, please.
>  Murray, W5XH
>
>>>>
Well Murray I've built 3 Screwdriver antennas and several
others including the Bugcatcher.  I hope my experience helps
you out.


Type                     Pro's                  Cons
------------------------------------------------------------
Bug catcher           Excellent gain     Inconvenient to
                                                     change bands

                            High power         Big and obtrusive
...........................................................
Screwdriver           Excellent gain     Low power (300W)

                            Easy to change   More moving parts
                            bands
...........................................................
Hustler                  Fair gain             Inconvenient to
                                                     change bands

                                                      Low power
...........................................................
Ham stick             low gain               low power


In closing most all of these antennas preform just about
equal on 40 meters and above, but 80 meters is what
separates the mobile antennas. If you need any more
info just ask.




                             "73" Gary KF9CM




From [e-mail] Sun Apr 28 13:09:55 1996
From: aor <[e-mail]>
Newsgroups: rec.radio.amateur.antenna
Subject: Re: Mobile Antenna for 27Mhz
Date: Wed, 24 Apr 1996 12:46:11 -0400
Message-ID: <[e-mail]>
References: <4kpti6$[e-mail]>

[e-mail] wrote:
>
> I am trying to build a beam type of antenna for a 27Mhz mobile. Does
> anyone have any models of this or ideas??? Even if you have formulas or
> theory I would be very interested.
>
> Thanks


One of the easiest ways to do this is by using two
antennas and phasing them.  One example would be to
buy two 9' whip antennas and mount them 9' feet
apart (1/4 wave on 27 MHz).  Feed them in phase by
using two equal runs of (odd 1/4 wave) 75 ohm coax
from a tee-connector on your radio.  The pattern
will be broadside to the two antennas.  With about
3db of gain over a single antenna.

You see truck drivers with two antennas, you don't
see the phasing harness, and the pattern favors the
front and back (broadside) by 3 db (double your
radiated power) at the expense of side radiation
(end-fire).  The principles are the same.

There are a lot of other things to consider
assuming you can put two antennas 9' apart on a
car, have good grounding, and a good ground plane.
There are other methods by using 90 degrees phasing
and 1/4 wave spacing...  but that is another story.
This resembles a 2-3 element beam pattern.

It is a lot of fun to do, 75 ohm coax is cheap, and
one centrally mounted antenna is usually better
than multiple antennas for 99% of the population.
Besides, how did you plan on turning this "beam"
???  Hi Hi

For 30 bucks, order the ARRL Antenna Handbook and
read up on the subject.

See ya,

Al  NW2M


From [e-mail] Sun Apr 28 13:09:56 1996
From: [e-mail]
Newsgroups: rec.radio.amateur.antenna
Subject: Re: Mobile Antenna for 27Mhz
Date: 27 Apr 1996 05:10:18 GMT
Message-ID: <4lsa7q$[e-mail]>
References: <4kpti6$[e-mail]> <[e-mail]>

aor <[e-mail]> wrote:
>[e-mail] wrote:
>>
>> I am trying to build a beam type of antenna for a 27Mhz mobile. Does
>> anyone have any models of this or ideas??? Even if you have formulas or
>> theory I would be very interested.
>>
>> Thanks
>
>
>One of the easiest ways to do this is by using two
>antennas and phasing them.  One example would be to
>buy two 9' whip antennas and mount them 9' feet
>apart (1/4 wave on 27 MHz).  Feed them in phase by
>using two equal runs of (odd 1/4 wave) 75 ohm coax
>from a tee-connector on your radio.  The pattern
>will be broadside to the two antennas.  With about
>3db of gain over a single antenna.
>
>You see truck drivers with two antennas, you don't
>see the phasing harness, and the pattern favors the
>front and back (broadside) by 3 db (double your
>radiated power) at the expense of side radiation
>(end-fire).  The principles are the same.
>
>There are a lot of other things to consider
>assuming you can put two antennas 9' apart on a
>car, have good grounding, and a good ground plane.
>There are other methods by using 90 degrees phasing
>and 1/4 wave spacing...  but that is another story.
>This resembles a 2-3 element beam pattern.
>
>It is a lot of fun to do, 75 ohm coax is cheap, and
>one centrally mounted antenna is usually better
>than multiple antennas for 99% of the population.
>Besides, how did you plan on turning this "beam"
>???  Hi Hi
>
>For 30 bucks, order the ARRL Antenna Handbook and
>read up on the subject.
>
>See ya,
>
>Al  NW2M

Thanks for the info. I'll look into that. I had heard that you can make
one of the antennas the hot and another the ground or backdoor.
Suppossedly the backdoor should act like a reflector.





From [e-mail] Sun Apr 28 13:09:57 1996
From: [e-mail] (W8JI  Tom)
Newsgroups: rec.radio.amateur.antenna
Subject: Re: Need help installing mirrored j pole
Date: 22 Apr 1996 13:52:45 -0400
Message-ID: <4lgh1d$[e-mail]>
References: <[e-mail]>

In article <[e-mail]>, [e-mail]
writes:

>I have just finished constructing a mirrored j pole for 2M. I believe
>that the construction has gone well...when testing the SWR prior to
>installation the meter gives a reading of 1.3 to 1 at 147mhz...however
>after attatching the antenna to the tower leg via a 30 inch stand off
>the SWR jumped to approx 4 to 1.
>What is the correct mounting procedure for this type of antenna?
>Any responses will be appreciated...KE4SZG
>
>

At least two things are going on here.

The bottom of the J pole is hot with common mode RF, and the type of
ground impedance applide at the "ground point" affects the pattern and
SWR.

Tower interaction also changes the impedance of the J pole and the SWR.

You've got quite a change, so you either have a combo of both of these or
a bad connection somewhere. Check your connections and then retune the J
pole when mounted in the final location.

73 Tom


From [e-mail] Sun Apr 28 13:09:58 1996
From: [e-mail]
Newsgroups: rec.radio.amateur.antenna
Subject: Need help installing mirrored j pole
Date: 22 Apr 96 09:49:12 CDT
Distribution: world
Message-ID: <[e-mail]>

Need help with installing a mirrored j pole antanna ( side mounted to
tower leg.
I have just finished constructing a mirrored j pole for 2M. I believe
that the construction has gone well...when testing the SWR prior to
installation the meter gives a reading of 1.3 to 1 at 147mhz...however
after attatching the antenna to the tower leg via a 30 inch stand off
the SWR jumped to approx 4 to 1.
What is the correct mounting procedure for this type of antenna?
Any responses will be appreciated...KE4SZG



From [e-mail] Sun Apr 28 13:10:00 1996
From: [e-mail] (Gary V. Deutschmann, Sr.)
Newsgroups: rec.radio.amateur.antenna
Subject: Re: Need help installing mirrored j pole
Date: Thu, 25 Apr 1996 17:01:31 GMT
Message-ID: <4lob97$[e-mail]>
References: <[e-mail]> <4lgh1d$[e-mail]>

[e-mail] (W8JI  Tom) wrote:

>In article <[e-mail]>, [e-mail]
>writes:

>>I have just finished constructing a mirrored j pole for 2M. I believe
>>that the construction has gone well...when testing the SWR prior to
>>installation the meter gives a reading of 1.3 to 1 at 147mhz...however
>>after attatching the antenna to the tower leg via a 30 inch stand off
>>the SWR jumped to approx 4 to 1.
>>What is the correct mounting procedure for this type of antenna?
>>Any responses will be appreciated...KE4SZG
>>
>>

>At least two things are going on here.

>The bottom of the J pole is hot with common mode RF, and the type of
>ground impedance applide at the "ground point" affects the pattern and
>SWR.

>Tower interaction also changes the impedance of the J pole and the SWR.

>You've got quite a change, so you either have a combo of both of these or
>a bad connection somewhere. Check your connections and then retune the J
>pole when mounted in the final location.

>73 Tom

Did you use PVC for your mounting boom?  Metal won't cut it!

I have two mirror image Js, neither changed SWR when mounted to either
a wooden house gable or to an aluminum tower.  The 6-meter mirrored-J
is powered by a solenoid to swing it from vertical to horizontal at
the touch of a button.  The SWR changes slightly between vertical and
horizontal, from about 1.2-1 to 1.3-1, on the gable of the house, the
SWR was 1.2-1 vertical and 1.4-1 horizontal.

All coax is run through the center of the boom on the mirrored-Js and
inside the antenna itself on Js and stacked-Js.....

TTUL - 73+ de Gary - KG0ZP






From [e-mail] Sun Apr 28 13:10:01 1996
From: [e-mail]
Newsgroups: rec.radio.amateur.antenna
Subject: Q: Transmission line formulas for cone over a plane
Date: 22 Apr 1996 16:34:21 -0700
Message-ID: <4lh51t$[e-mail]>

Does anybody out there know where I can find the formulas of the
following transmission line structure:

a (inverted) cone over a ground plane?


Thank you in advance.

73 de Serge Stroobandt, G/ON4BAA


From [e-mail] Sun Apr 28 13:10:01 1996
From: [e-mail] (Wholesale Products)
Newsgroups: rec.radio.amateur.antenna
Subject: Recoton At Wholesale Prices
Date: 26 Apr 1996 10:56:13 GMT
Message-ID: <4lqa4d$[e-mail]>

Complete line of Recoton products at wholesale prices, including parsec
antennas.  Check out:

http://www.wholesaleproducts.com

We also stock a huge inventory of VCRs, blank videotapes, blank audio tapes,
camcorders, GO-VIDEO - direct from the manufacturer.  If you don't see what
you want, ask!

Sincerely,
Wholesale Products
Internet Sales Division
[e-mail]






From [e-mail] Sun Apr 28 13:10:02 1996
Newsgroups: rec.radio.amateur.antenna
From: Thomas Bohl <[e-mail]>
Subject: Search article about magnetic loop
Message-ID: <[e-mail]>
Date: Wed, 24 Apr 1996 17:47:15 GMT

Dear om,

could you please let me know from where I can get a copy of

Patterson, K H
Down-to-earth Army antenna
ELECTRONICS, 40, (1967), August 21, pp 111-114 ?


Mni tks es 73 de Thomas, F5SWE.


From [e-mail] Sun Apr 28 13:10:03 1996
From: [e-mail] (My name is...)
Newsgroups: rec.radio.amateur.antenna
Subject: SGC-230 w/9 foot fiber glass whip?
Date: 24 APR 96 10:20:01
Message-ID: <4lldd2$[e-mail]>

Has anyone tried this combo? How well did it work on 75/40 meters??

Ken


From [e-mail] Sun Apr 28 13:10:04 1996
From: [e-mail] (David Toste)
Newsgroups: rec.radio.amateur.antenna
Subject: Slinky Antennas?
Date: 23 Apr 1996 06:29:38 GMT
Message-ID: <4lhtci$[e-mail]>
Reply-To: [e-mail] (David Toste)


I just read a small article about using two slinkies as a 'End Fed
Zepp'Ant. Anyone try and play around with the slinkies and if so how did
it work out?


--
 David Toste [VE3TOS]        Internet - [e-mail]
 Don Mills, Ontario.          SWLOGit - The Ultimate Shortwave Listeners
 ftp.virginia.edu  /pub/swlogit/        Software. (Fidonet: 1:250/930)
*NEW* http://www.interlog.com/~saturn/SWLOGit.html (SWLOGit Web Page)


From [e-mail] Sun Apr 28 13:10:05 1996
From: [e-mail] (Gary V. Deutschmann, Sr.)
Newsgroups: rec.radio.amateur.antenna
Subject: Re: Slinky Antennas?
Date: Thu, 25 Apr 1996 01:38:42 GMT
Message-ID: <4lml6j$[e-mail]>
References: <4lhtci$[e-mail]>

[e-mail] (David Toste) wrote:


>I just read a small article about using two slinkies as a 'End Fed
>Zepp'Ant. Anyone try and play around with the slinkies and if so how did
>it work out?


>--
> David Toste [VE3TOS]        Internet - [e-mail]
> Don Mills, Ontario.          SWLOGit - The Ultimate Shortwave Listeners
> ftp.virginia.edu  /pub/swlogit/        Software. (Fidonet: 1:250/930)
>*NEW* http://www.interlog.com/~saturn/SWLOGit.html (SWLOGit Web Page)


I used a pair of those small slinkies (1-1/4 inch dia) to make a
portable mirrored J, works as well as if the pipe was solid.

I have also used them as end fed verticals with moderate results, but
nothing to write home about.....

TTUL
Gary






From [e-mail] Sun Apr 28 13:10:06 1996
From: [e-mail] (DARRYL LINKOW)
Newsgroups: rec.radio.amateur.antenna
Subject: Tuning a Saturn 6 PROBLEM
Message-ID: <[e-mail]>
Date: Wed, 24 Apr 96 18:27:00 -0800
Distribution: world
Reply-To: [e-mail] (DARRYL LINKOW)


4/24/96

Hello all and thanks for reading this.  I just received an old
Saturn 6 antenna and am having a real difficult time tuning it.  I
am using an MFJ-259 analyzer and can not get the antenna anywhere
below 2.5 to 1 SWR on ANY frequency.  I have tried adjusting the
capacitor plate on the antenna in multiple places and can not get
the SWR lower.  I am trying to set the antenna for a center
frequency of about 50.135 Mhz.  I am just wondering if the antenna
is missing anything?  It has two screw posts that are mounted on a
piece of phenolic board.  I connected one with the shield and the
other with center conductor of a piece of RG-58.  Might there be a
balun that came with this antenna that I am missing?  Any help
would be appreciated.  If you own a Saturn 6, please tell me if you
have experienced anything like this, or if I am missing a part of
the antenna.  Thank you and 73, Darryl KE6IHA

---
 * OLX 2.2 * Darryl Linkow [phone]  9 am - 5 pm PDT


From [e-mail] Sun Apr 28 13:10:07 1996
From: [e-mail] (Pat Masterson)
Newsgroups: rec.radio.amateur.antenna
Subject: Two beams on one feedline ?
Date: 24 Apr 1996 15:50:59 -0400
Message-ID: <4lm0n3$[e-mail]>

 I want to use two 440 beams to link two packet nodes. All
that is available to me are standard, 50 ohm antennas. How
can I connect them to one radio, presenting a decent
impedance load? Is there a trick with matching sections of
coax I can use? Thanks. -pat


--
*  Pat Masterson  B38-111, Northrop Grumman Corp.*  Ham:KE2LJ
*  1111 Stewart Ave., Bethpage NY 11714          *  Packet: [e-mail]
*  516-346-6316                                  *  President Grumman Amateur
*  email: [e-mail]                        *  Radio Club  WA2LQO


From [e-mail] Sun Apr 28 13:10:07 1996
Date: 26 Apr 1996 10:11:56 EDT
Newsgroups: rec.radio.amateur.antenna
From: [e-mail] (Hugh Duff)
Message-ID: <[e-mail]>
References: <[e-mail]>
Subject: Re: URL Correction


> ->Sorry This is the correct URL...
> ->cut and paste it.
>
> ->located at-->   http://users.aol.com/maxfro/private/tunekit2.html
>
> I tried that one and it doesn't work either.
>


This is the tried and true URL for "TUNEKIT"
(I have no idea why the original poster had it wrong twice !?!?):

http://users.aol.com/maxfro.private

CUL..
Hugh Duff  VA3TO  Toronto



---
 ■ NFX v1.3 [000]


From [e-mail] Sun Apr 28 13:10:08 1996
From: "Sid Phillips, W5SP" <[e-mail]>
Newsgroups: rec.radio.amateur.antenna
Subject: Re: URL Correction
Date: Fri, 26 Apr 1996 13:42:04 -0500
Message-ID: <[e-mail]>
References: <[e-mail]> <[e-mail]>
Reply-To: [e-mail]
To: Clinton Peebles <[e-mail]>

Clinton Peebles wrote:
>

> ->located at-->   http://users.aol.com/maxfro/private/tunekit2.html
>
> I tried that one and it doesn't work either.

It worked for me at 18:41:49Z
                                Sid, W5SP


From [e-mail] Sun Apr 28 13:10:09 1996
From: [e-mail] (Clinton Peebles)
Newsgroups: rec.radio.amateur.antenna
Subject: Re: URL Correction
Date: Thu, 25 Apr 1996 14:03:42 GMT
Message-ID: <[e-mail]>
Distribution: world
References: <[e-mail]>

->Sorry This is the correct URL...
->cut and paste it.

->located at-->   http://users.aol.com/maxfro/private/tunekit2.html

I tried that one and it doesn't work either.


From [e-mail] Sun Apr 28 13:10:10 1996
From: [e-mail] (David Greene)
Newsgroups: rec.radio.amateur.antenna
Subject: want advice on mag mount antennas
Date: 25 Apr 96 14:41:45 GMT
Message-ID: <[e-mail]>



I'm just now breaking into vhf/uhf operation and am not
sure about which type of mobile antenna to use.  I have
just bought a dual band 2M/440 HT and want to use it in the
car.  I don't plan on running any kind of amplifier, so I'll
normally be running 5 watts or less so I'll need a good antenna.

I've read that a 5/8 wave antenna gives a bit better gain than
a 1/4 wave.  I've also heard that a 5/8 wave 2M antenna works
marginally on 440.  I'm more interested in getting peak performance
on 2M, and only occasionally chatting on 440 since we only have one 440
repeater in the area, so I'm thinking that perhaps a good 5/8 wave
2M mobile would be best for me.

Here's my questions:

1.  Does a dual band (2M/440) antenna sacrifice any performace
    over a monobander for vertical mobile antennas?

2.  Are there any performance disadvantages when using a mag mount
    antenna if it is mounted properly.

3.  WHat are some of the best brands of 2M mobile verticals?

4.  What are some of the best mag mount 2M mobile verticals?

5.  What are some of the best mag mount 2M/440 mobile verticals
    (mag or hard mount)?

Please respond to me via email at [e-mail] and thanks in
advance for any advice you can give me.

73's Dave
AA9BI


--
--
Dave Greene        Heurikon Corp.        800-356-9602


From [e-mail] Sun Apr 28 13:10:11 1996
From: [e-mail] (Jim Fellows)
Newsgroups: rec.radio.amateur.antenna
Subject: What limits ant power?
Date: 22 Apr 1996 16:49:11 GMT
Message-ID: <4lgda7$[e-mail]>

After seeing a post recently that mentioned power handling capablities of
antennas, I got to wondering just what does limit antenna power handling?

This post in particular mentioned that most VHF/UHF antennas can only handle u
p
to 200W.  I can see the possiblity that some of these fiberglass "wonder
antennas" have some added low power components in them.  (They are wonder
antennas to me since I see no way they can get the gain that is claimed.)

But say we are talking about a yagi with one of those telescoping sleeve gamma
matches. What limits the power handling to it?  Is it solely the dielectric in
the sleeve match?  Or is it something else?  And what of all-metal antennas su
ch
as quads, quagis, helicals or whips?   I haven't checked, but I assume that th
e
"good quality" connectors are capable of taking higher powers.

Now don't come back asking what in the world I want to run over 200W on VHF/UH
F
for.  I don't.  I can see that someone doing EME would but I don't.  I'm just
wondering.


Jim
KF6AGJ



From [e-mail] Sun Apr 28 13:10:13 1996
From: [e-mail] (Tom Bruhns)
Newsgroups: rec.radio.amateur.antenna
Subject: Re: What limits ant power?
Date: 26 Apr 1996 22:48:17 GMT
Message-ID: <4lrjrh$[e-mail]>
References: <4lrdbk$[e-mail]>

WB3U ([e-mail]) wrote:
(re: antenna power handling capacity...)

: It's strictly a matter of voltage and current capability.  The size of
: the conductors limits the current that can be applied without
: overheating.  The spacing between the conductors and the insulation
: between them (or the rating of discrete components) limits the voltage
: that can be applied without breakdown or arcing.

One other factor worth mentioning:  technically it's part of Jack's last
sentence, but it's possible for the field around an "isolated" conductor
to become high enough that the air in the vicinity gets ionized, and you
end up with corona.  That's why there is sometimes a ball put at the end
of a small diameter radiator that will be fed high power.  Small conductor
diameters lead to heating at current maxima and corona at voltage maxima.

--
Cheers,
Tom
[e-mail]


From [e-mail] Sun Apr 28 13:10:13 1996
From: [e-mail] (Graham Seale)
Newsgroups: rec.radio.amateur.antenna
Subject: Re: What limits ant power?
Date: Thu, 25 Apr 1996 02:09:01 GMT
Distribution: world
Message-ID: <[e-mail]>
References: <4lgda7$[e-mail]>
Reply-To: [e-mail]

In message <4lgda7$[e-mail]> Jim Fellows wrote:

> After seeing a post recently that mentioned power handling capablities of
> antennas, I got to wondering just what does limit antenna power handling?

Hi Jim.

Too much power causes voltages at the ends of the elements enough to
ionise air and cause corona discharge from sharp edges. I once put power
into a car mounted whip made of a wire in a fibreglass rod. The end caught
fire, stank to high heaven and left the top few inches as a little rusty
rod sticking out of a pile of fibreglass tassles and burnt epoxy.


--
Graham Seale


From [e-mail] Sun Apr 28 13:10:14 1996
From: Cecil Moore <[e-mail]>
Newsgroups: rec.radio.amateur.antenna
Subject: Re: Zepp, Double Extended - Why?
Date: 18 Apr 1996 21:28:03 -0700
Message-ID: <4l74oj$[e-mail]>
References: <4kneet$[e-mail]> <[e-mail]>

[e-mail] (Pete Soper) wrote:
.>If you can demonstrate broadside lobes on two frequencies I'd be
interested
>in the details.

Hi Pete, for instance, a 102 ft. dipole (G5RV) has broadside
lobes on an infinite number of frequencies from 3-12 MHz. Any
"dipole" shorter than about 11/8 wavelength has broadside lobes.

73, Cecil, KG7BK, OOTC




From [e-mail] Sun Apr 28 13:10:16 1996
From: [e-mail] (t▓s)
Newsgroups: rec.radio.amateur.antenna
Subject: ºTower Wanted - Californiaº
Date: Sat, 27 Apr 1996 18:20:24 GMT
Message-ID: <4ltoig$[e-mail]>

I am looking for a 451X Tower- (I think that's the right p/n)
It is a 40' crankup tower that when nested is only 10' high

Does anyone have one they want to unload?

Please forward any info to

t▓s
[e-mail]


********WARNING********
Unsolicited *commercial* email is subject to download/archival fee of
$525.00 US per message.
Viewing this message and/or E-mailing to the forementioned address denotes
acceptance of these terms.



From [e-mail] Mon Apr 29 16:35:36 1996
From: Chuck Vaughn <[e-mail]>
Newsgroups: rec.radio.amateur.antenna
Subject: Re: Antenna Location
Date: Sat, 27 Apr 1996 14:07:53 -0700
Message-ID: <[e-mail]>
References: <[e-mail]>

Jerry Boyd wrote:
>
> If anyone on here has access to TA or some other means of answering my
> question (direct via [e-mail]) I'd really appreciate it.  I'm
> moving to a new QTH and am involved in HF Contests and DXing.  New QTH
> is at about 1900 feet elevation.  Obstructions I am concerned about are:
> Mountain peaks of 5100-5900 feet about 8 miles away from my QTH and
> smaller peaks of 2800-3400 feet 2 1/2 - 3 miles away.  Fortunately these
> are all within about 90 degrees leaving 270 degrees unobstructed.  Part
> of the obstructed path is straight over the North Pole.  Unfortunately,
> the other is to JA.  Problem?!?!
>
> Any info/thoughts appreciated
>

For others who would like to know:

Worst Case:

   ARCTAN(((3400' - 1900')/5280')/2.5 miles) = 6.5 degrees

Second Worst:

   ACRTAN(((5900' - 1900')/5280)/6 miles = 5.4 degrees

This of course does not include curvature of the earth. From a hilltop
that slopes off those numbers are not insignificant but compared to us
flatlanders I'm sure it will still be great. You'd be surprised how much
DX on the higher freqs is at an angle below 5 degrees and even lower on
6m.

Chuck Vaughn - AA6G    ([e-mail]>


From [e-mail] Mon Apr 29 16:35:37 1996
From: Cecil Moore <[e-mail]>
Newsgroups: rec.radio.amateur.antenna
Subject: Re: Antenna Theory Question
Date: 27 Apr 1996 12:35:03 -0700
Message-ID: <4ltst7$[e-mail]>
References: <4l80tb$[e-mail]> <4ld726$[e-mail]> <[e-mail]> <4lis67$[e-mail]> <[e-mail]>

[e-mail] (Graham Seale) wrote:
>
>I just do
>not know which of our revered physical laws  - true as they are, come
>with a mathematical baggage that will one day give way to more elgant
>models.

Hi Graham, IMO somewhere in the universe there exists more elegant
models for every one of our revered true physical laws. Every 50
years the human race looks back and says, "Boy, were they wrong
50 years ago."

73, Cecil, KG7BK, OOTC




From [e-mail] Mon Apr 29 16:35:39 1996
From: [e-mail] (Graham Seale)
Newsgroups: rec.radio.amateur.antenna
Subject: Re: Antenna Theory Question
Date: Sat, 27 Apr 1996 12:26:31 GMT
Distribution: world
Message-ID: <[e-mail]>
References: <4l80tb$[e-mail]> <4ld726$[e-mail]> <[e-mail]> <4ljpq3$[e-mail]>
Reply-To: [e-mail]

In message <4ljpq3$[e-mail]> Bill Meara wrote:

> Now, as for equal rights, I continue to be egalitarian!  I agree that if
> you put the antenna in a Faraday cage and only let the near M field out,
> you'd still get an EM wave.  But I also _suspect_ that if you put the
> antenna in a ferromagnetic shield that blocked the magnetic field, the
> varying electric field could do the job by itself and would generate an
> EM wave.

You are right to be egalitarian. We can all stop trying to make one kind
of field without the other. My magloop shield, if made as a true Faraday
shield, would not have the overlapped "gap" that stops the shield being
a "shorted turn". A shield can only be a shield if it is allowed to conduct
the currents that will force all the places at the shield surface to be
at the same potential.

With the gap, the loop inside will cause conditions for the shield to have
voltages across the gap, and currents in its body rather similar to what
would have happened had the shield not been there. (Kevin's and Gerry Butler's
input here acknowledged)

E-fields and H-fields are alternately occuring storage forms of the same
energy on the move. Have you ever wondered why ordinary transformers will
not transfer energy unless it is time-varying? It is an extremely short
range transmission with the Rx right in the near field, and in a high
permeability medium. (I fumble at the permittivity of the core material!)
Surely the parallel with my antenna's refusal to transmit unless I make
time varying currents in it is too obvious to ignore!

73 G4WNT
--
Graham Seale


From [e-mail] Mon Apr 29 16:35:40 1996
From: Cecil Moore <[e-mail]>
Newsgroups: rec.radio.amateur.antenna
Subject: Re: Antenna Theory Question
Date: 28 Apr 1996 16:37:02 -0700
Message-ID: <4m0veu$[e-mail]>
References: <4l80tb$[e-mail]> <4ld726$[e-mail]> <[e-mail]> <4lis67$[e-mail]> <[e-mail]> <4ltst7$[e-mail]> <[e-mail]>

"Ian White, G3SEK" <[e-mail]> wrote:
>Moral: it works best to assume that physical laws *always* hold true;
>and that if they don't seem to, the fault is not in physical reality but
>in our understanding of it.

Hi Ian, I find your posting slightly unbelievable.

We have proven that faster than light communications occurs.

We have proven that your sacred "physical reality" does not
originate here.

We have proven that EM waves do not follow straight lines and
cannot propagate through nothing.

We have proven that space is not linear.

I can't wait for you to state a physical law that has been true
forever and will last forever.

73, Cecil, KG7BK, OOTC




From [e-mail] Mon Apr 29 16:35:41 1996
From: [e-mail] (Bill W0IYH)
Newsgroups: rec.radio.amateur.antenna
Subject: ANTENNA THEORY QUESTIONS
Date: 28 Apr 1996 17:37:50 GMT
Distribution: world
Message-ID: <4m0ade$[e-mail]>
Reply-To: [e-mail]

Reference: Kraus "Electromagnetics, 4th Edition" Secs.15-5 and 15-6

Let's consider the *far field* of a short dipole:

The *far field* of a short dipole is calculated on the basis of the
current distribution in the dipole. The E and H fields are

              E=-(del A/del t)   H=(1/mu0) * curl A

where A is the retarded vector potential, which is a function of the
radiator current. The quantity A is thus a *link* between E and H.

Therefore one thing that we need to appreciate is that E and H are not
mutually exclusive entities. From Maxwell's equations in free space

                curl H = dD/dt       curl E = -dB/dt

The first is Ampere's law and the second is Faraday's law. The
striking thing about the Ampere equation is how an H field creates
a D (or E) field and a displacement current, and how the time-varying
E field (displacement current) can produce an H field. The Faraday equation
also says that an E field and an H (or B) field can create each other.
These two equations say the same thing, basically, in slightly
different ways. And the power density at a point in the far field is just
the vector product of E and H.

The conclusion seems to be that for the far field the E field and H field,
as calculated from the radiator current, coexist and, in fact, *create*
each other. This relationship between E and H exists also at the radiator,
and another item, the scalar potential V, is involved in the near-field.

It is also true that the displacement current in a capacitor, air or solid
dielectric, produces an H field, and its value can be calculated.
Kraus gives an example (Problem 11-5-2).

Bill



From [e-mail] Mon Apr 29 16:35:43 1996
From: [e-mail] (Roy Lewallen)
Newsgroups: rec.radio.amateur.antenna
Subject: Re: Beginner question
Date: Mon, 29 Apr 96 08:46:37 GMT
Message-ID: <4m1vjb$[e-mail]>
References: <4logk8$[e-mail]>

In article <4logk8$[e-mail]>, [e-mail] wrote:
>I'm just starting to learn theory so be easy on me... :-)
>I just don't understand the diagrams they show about attenna 'power' -
>I guess they call this the lobe.  What determins the solid line?
>Also is this supposed to be the view from above (below) the attenna or
>from the side? The line seems to limit the signal - isn't the signal
>radiating completely around the antenna? So what's the line - some
>value to fit within the diagram?

The diagrams you see showing antenna patterns are graphs which show the
strength of the radiated signal in each direction from the antenna when
it's used for transmitting. (This is the same as its ability to receive
from each direction, too, but I'll use the transmitting case for this
discussion.)

The distance from the solid line to the center of the graph is proportional
to the strength of the signal the antenna produces in that direction. (The
scale isn't necessarily linear, but the farther the line is away from the
center, the stronger the signal in that direction.)

Here's how the plot could hypothetically be created. You connect a
transmitter to your antenna and send out a constant signal. Then you go ten
miles due north and, with a receiver, record the strength of the signal.
Let's say the strength is 9 Sterbys. (I made this unit up, but the absolute
strength doesn't matter for this example.) You take a sheet of paper and
label the top of the sheet "north". From the center of the sheet, move your
pencil "north" 9 cm and put a dot. Now, still keeping ten miles from your
station, travel until you're exactly northeast of it. Measure the signal
there. Suppose it's 6 Sterbys. On your piece of paper, go out 6 cm
"northeast" (45 degrees clockwise from "north") from the center and put a
dot. Continue on around the station, measuring the signal at various
directions and put the dots on the corresponding points on your graph. When
you're done, connect the dots and you have the pattern.

The actual pattern, or graph of the signal strength, is actually a three-
dimensional figure, since the antenna radiates with different strengths at
each angle of elevation as well as azimuth. The common two-dimensional
antenna pattern is a "slice" through the full 3-D pattern to give the
signal strength for a given azimuth or elevation angle. The "slice" can be
made in a variety of ways, and you can't tell which kind of "slice" was
made just by looking at the graph unless you already know something about
the antenna pattern. In the example above, you were measuring and plotting
the azimuth pattern at a zero elevation angle (i.e., at the horizon).

For a better description and some drawings, see Chapter 2 of The ARRL
Antenna Book. This book is also likely to answer other questions you'll
have about antennas.

73,
Roy Lewallen, W7EL


From [e-mail] Mon Apr 29 16:35:43 1996
From: [e-mail] (John Kolb)
Newsgroups: rec.radio.amateur.antenna
Subject: Re: Fiberglas Coil Forms
Date: 28 Apr 1996 17:55:25 GMT
Message-ID: <4m0bee$[e-mail]>
References: <4llnra$[e-mail]> <4loit0$[e-mail]> <4lqqej$[e-mail]>

Cecil Moore ([e-mail]) wrote:

: Thanks Jack, 73 magazine carries an article this month about copper
: tape for coils. Since copper tape is flat, wouldn't it follow that
: the small adjacent edges of the tape would result in minimum
: capacitance?

Interesting article - does anyone have any sugestions as to what
type of store sells copper tape?




From [e-mail] Mon Apr 29 16:35:45 1996
From: Bruce Burke <[e-mail]>
Newsgroups: rec.radio.amateur.antenna
Subject: Re: Field Day wire antenna hints needed
Date: Mon, 29 Apr 1996 07:44:32 -0400
Message-ID: <[e-mail]>
References: <[e-mail]>

Michael L. Ardai wrote:
>
>
> What would be the best wires to use for FD?  T
>
> Thanks and 73.
> /mike
>
> BTW, if you are in the Boston area for FD, stop on by.  We will be at
> Larz Andersen park, behind the transportation museum in Brookline.
>


At least on 80 and 40 meters, we've always had good sucess with
an inverted V. The 80 and 40 elements are tied together at the feedpoint.
The ends are supported seperately.

73,
Bruce, WB4YUC


From [e-mail] Mon Apr 29 16:35:46 1996
From: [e-mail] (Clinton Peebles)
Newsgroups: rec.radio.amateur.antenna
Subject: Help: 6m Dipole Ant
Date: Sun, 28 Apr 1996 13:33:00 GMT
Message-ID: <[e-mail]>
Distribution: world
References: <4lp20o$[e-mail]>


S>How long would the two individuals legs need to be for a 6m centerfed
S>dipole om 50.125 mhz?

I just built one yesterday.  I used parts from an old 5/8 wave CB base
antenna.  I didn't even have to cut the tube, though it was a bit
shorter than I wanted.  I wanted 4'5" per side, but had to use hmmm,
can't remember exactly, but I think it's 4' 3.5" or something.  SWR is
good at the low end, but not that great at the top end of the band.

I used the plans from April/94 QST for a 10m dipole.
---
 ■ QMPro 1.53 ■ Yea, yea...once a hobby, now an expensive addiction!


From [e-mail] Mon Apr 29 16:35:47 1996
From: [e-mail] (Paul Hattemore)
Newsgroups: rec.radio.amateur.antenna
Subject: HF Antennas
Date: Sun, 28 Apr 1996 09:07:03 GMT
Message-ID: <[e-mail]>
Reply-To: [e-mail]

1.  I am looking for ways of estimating the 'gains' over an isotropic
antenna for various types of wire antennas at a range of frequencies.
Antennas include:
        a. Half wave vertical dipole
        b. 3/4 wave sloping wire
        c. Half wave horizontal dipole
        d. 1/4 wave vertical monopole

2. I am attempting to communicate over a 5500 Km path using 2 hops
which requires a take off angle of less than 10 degrees.  This distant
end is able to utilise a rotatable log periodic and always booms in
but the local end currently uses an inverted V off a 70' (21.5m) mast
and is very weak at the distant end.  The local site can only use
simple wire antennas so a log periodic is out of the question (it
needs to be mobile/ have a short - up to 60 min - set up time) .  Both
sites have 1Kw tx and op ssb voice/data.  The antenna need to be fed
by coax. The eqpt avail is 2 x 21.5m masts, 2 x 12m masts and lots of
copper wire and insulators.
Can anyone suggest possible antennas to use as an alternative to the
inverted V which might improve the s/n ratio at the distant end ?

Paul




From [e-mail] Mon Apr 29 16:35:48 1996
From: [e-mail] (MARKTAINT)
Newsgroups: rec.radio.amateur.antenna
Subject: Re: HF Antennas
Date: 28 Apr 1996 15:54:14 -0400
Message-ID: <4m0id6$[e-mail]>
References: <[e-mail]>
Reply-To: [e-mail] (MARKTAINT)

For a simple, but highly effective wire antenna (single-band) I really
like the half square antenna. It's two 1/4 wave verticals fed in phase by
a 1/2 wave wire. Another way to think of it is this: a full wave length
wire fed 1/4 way in from the end. that 1/4 wave hangs straight down and
the far 1/4 end hangs down too. the 1/2 wave in between is horizontal.
Antennas West makes them or you can easily make them yourself.  It's let
me have a booming signal into Papua New Guinea from here in Minnesota


From [e-mail] Mon Apr 29 16:35:50 1996
From: [e-mail]
Newsgroups: rec.radio.amateur.antenna
Subject: Re: Humor:  You might be a ham if...
Date: 29 Apr 1996 03:42:20 GMT
Message-ID: <4m1dqs$[e-mail]>
References: <[e-mail]>
Reply-To: [e-mail]

In <[e-mail]>, [e-mail] (JAME
S MCEWEN) writes:
>
>
>
>You might be a ham if:

Can't get your zipper closed while reading this news group.

Forgive the crassness but I hope it was worth it to someone.
>
>If you window shop at Radio Shack
>If you introduce your wife as "[e-mail]"
>If you want an 8X CD-ROM for Christmas
>If the only jokes you receive are through e-mail
>If you use a CAD package to design your son's Pine Wood Derby car
>If you have used coat hangers and duct tape for something other than hanging
>coats and taping ducts
>If, at Christmas, it goes without saying that you will be the one to find the

>burnt-out bulb in the string
>If your ideal evening consists of fast-forwarding through the latest sci-fi
>movie looking for technical inaccuracies
>If you carry on a one-hour debate over the expected results of a test that
>actually takes five minutes to run
>If you have modified your can opener to be microprocessor driven
>If you know the direction the water swirls when you flush
>If you have ever taken the back off your TV just to see what's inside
>If a team of you and your coworkers have set out to modify the antenna
>on the radio in your work area for better reception
>If you thought the concoction ET used to phone home was stupid
>If you have never backed-up your hard drive
>If you have ever saved the power cord from a broken appliance
>If you have ever purchased an electronic appliance "as-is"
>If you see a good design and still have to change it
>If the salespeople at Circuit City can't answer any of your questions
>If you still own a slide rule and you know how to work it
>If you have more toys than your kids
>If you have a habit of destroying things in order to see how they work
>If the microphone at a meeting doesn't work and you rush up to fix it.
>If you can remember 7 computer passwords but not your anniversary
>If you have ever owned a calculator without an equal key
>If you did the sound system for your senior prom
>If your girlfriend says the way you dress is no reflection on her
>If your wristwatch has more buttons than a telephone
>If you have more friends on the Internet than in real life
>If you thought the real heroes of "Apollo 13" were the mission controllers
>If you think your computer looks better without the cover
>If your wife hasn't the foggiest idea what you do at work
>If you know what http:/ stands for
>If you've ever tried to repair a $5.00 radio
>If your favorite part of the 6 o clock news is comparing their latest satelli
te
>weather picture with yours
>If your three year old son asks why the sky is blue and you try to explain
>atmospheric absorption theory
>
>



From [e-mail] Mon Apr 29 16:35:51 1996
From: [e-mail] (Graham Seale)
Newsgroups: rec.radio.amateur.antenna
Subject: Re: Humor: You might be a ham if...
Date: Sat, 27 Apr 1996 11:34:03 GMT
Distribution: world
Message-ID: <[e-mail]>
References: <[e-mail]> <4lo2rc$[e-mail]>
Reply-To: [e-mail]

In message <4lo2rc$[e-mail]> Ross Alexander wrote:

> BTW, I don't know that I've ever owned a calculator that did have an
> equal key :).

Hmm.. You must have stayed with Hewlett Packards.
My first Reverse Polish type was a (ahem..) "Sinclair Scientific" kit.
It was a bit of a disaster. When I tried HP's Reverse Polish with a built
in stack, life was transformed. I still keep an old Casio around for those
who just cannot relate to a calculator without an equals key.

73's G4WNT

--
Graham Seale


From [e-mail] Mon Apr 29 16:35:52 1996
From: Asmartuser <[e-mail]>
Newsgroups: rec.radio.amateur.antenna,rec.radio.amateur.equipment,rec.radio.amateur.misc
Subject: Hy-gain DX88 questions
Date: Wed, 24 Apr 1996 16:48:15 -0700
Message-ID: <[e-mail]>

Anyone can tell me experiencies with this kind of antenna?
What about the expansion kit for 160 m.?

Any suggestion will be appreciated.



73,
IZ2ADI, Maurizio


From [e-mail] Mon Apr 29 16:35:53 1996
From: [e-mail] (Collier Chun)
Newsgroups: rec.radio.amateur.antenna
Subject: Re: Larsen Fixes 2/70 problem identified by user
Date: Mon, 29 Apr 96 07:00:13 PST
Message-ID: <4m2i1e$[e-mail]>
References: <[e-mail]>

In article <[e-mail]>, [e-mail] says...
>
>Several weeks ago, an article was posted identifying a problem Larsen
>had with its NMO 2/70 B black open coil dual band whip.  The posting
>caused a corrective action request to be generated by Larsen's quality
>system.  The problem has now been corrected.

Is there a way to determine whether an antenna sitting on a dealer's shelf
is of post-fix vintage?

Collier Chun
NM7B




























From [e-mail] Mon Apr 29 16:35:55 1996
From: [e-mail] (Cecil A. Moore~)
Newsgroups: rec.radio.amateur.antenna
Subject: The Coax Mentality
Date: 28 Apr 1996 22:34:18 GMT
Distribution: world
Message-ID: <4m0rpa$[e-mail]>

There's an attitude amoung most hams that I'll call the
coax mentality. It prohibits these hams from really
knowing their antenna system. I'll start this thread
off. Anyone who has something useful to add, feel free.

1. Coax Mentality: It's too difficult to make measurements
along a transmission line - impossible without disturbing
the line.

Ladder-Line Mentality: It's easy to make measurements
along a transmission line without disturbing anything.

2. Coax Mentality: An antenna analyzer is too expensive
and doesn't have the necessary range of measurements.

Ladder-Line Mentality: A $10 pick-up loop will make all
the measurements one needs to know everything about
one's antenna system.

3. Coax Mentality: Cutting and trying is expensive and
time consuming. Splicing is almost impossible.

Ladder-Line Mentality: Cutting and trying is inexpensive
and easy. It as easy as twist-ties. Splicing is as easy
as using butt lug connectors.

4. Coax Mentality: SWR is the enemy. The SWR must be less
than 2:1

Ladder-Line Mentality: SWR is our friend. It is usually
less than 20:1 and transforms undesirable impedances
into impedances that are easy to match.

5. Coax Mentality: Unbalanced antenna tuners are
simpler and less expensive than balanced antenna tuners.

Ladder-Line Mentality: Maybe, but the balanced antenna
tuner *function* is certainly simpler, less expensive,
*and* more efficient than unbalanced antenna tuners.
If you know what you are doing, one single variable
capacitor will give a perfect match on all HF bands.

73, Cecil, KG7BK, OOTC  (not speaking for my employer)


From [e-mail] Mon Apr 29 16:35:57 1996
From: [e-mail] (Roger Grady)
Newsgroups: rec.radio.amateur.antenna
Subject: Re: Two beams on one feedline ?
Date: Sat, 27 Apr 1996 07:17:32 GMT
Message-ID: <4lshdg$[e-mail]>
References: <4lm0n3$[e-mail]>

[e-mail] (Pat Masterson) wrote:

> I want to use two 440 beams to link two packet nodes. All
>that is available to me are standard, 50 ohm antennas. How
>can I connect them to one radio, presenting a decent
>impedance load? Is there a trick with matching sections of
>coax I can use? Thanks. -pat

Since the antennas will be connected in parallel, the impedance of the
pair will be 25 ohms.  That won't be a very good match for your
(probably) 50 ohm feedline.  The best way to match them is  to step up
the impedance of each antenna to 100 ohms, then when you connect them
in parallel, you're back to 50.  You can do this by putting an
odd-multiple of 1/4 wavelength of 70 ohm coax between each antenna and
the junction point.  The formula for the impedance of the 1/4 wave
section is sqrt(Z1 * Z2), where Z1 and Z2 are the impedances between
which you want to match (50 and 100 in this case).   With most 70 cm.
yagis, you will need several 1/4 wavelengths in each section to cover
the distance to the common point, unless you hang it in space between
the antennas.  Don't forget to take the coax velocity factor into
account when figuring the length.

Another way is to use a 'power divider' which is nothing more than a
1/4 or 1/2 wave length of coax made of copper or aluminum tubing with
coax connectors on it.

If you can find back issues of Ham Radio magazine in a library, there
were a number of articles on the subject back in the mid to late 80's.

Good luck.

Roger Grady   K9OPO   [e-mail]





From [e-mail] Mon Apr 29 16:35:58 1996
From: [e-mail] ()
Newsgroups: rec.radio.amateur.antenna
Subject: Visalia Shootout
Date: Mon, 29 Apr 1996 02:08:29 GMT
Message-ID: <4m18f3$[e-mail]>

Can  anyone who was at Visalia summmarize the mobile hf antenna
shootut? Thanks