QRZ! Ham Radio 4/QRZ Ham Radio Callsign Database - Volume 4.iso/digests/antenna/940058.txt

Internet Message Format | 1994-11-13 | 17KB

Date: Tue,  8 Mar 94 04:30:14 PST
From: Ham-Ant Mailing List and Newsgroup <[e-mail]>
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Subject: Ham-Ant Digest V94 #58
To: Ham-Ant


Ham-Ant Digest              Tue,  8 Mar 94       Volume 94 : Issue   58

Today's Topics:
                         Battle Creek Special
                        Design of Cubical Quad
                      Dipole or Vertical for DX?
                          MFJ SWR Analyzers
                         R5 info/part needed
                     Radials for rooftop antenna
                        Simple Signal Question
                         Slim-jim dimensions?
                                 test
                     ZL Special on 6m verse Yagi

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We trust that readers are intelligent enough to realize that all text
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policies or positions of any party.  Your mileage may vary.  So there.
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Date: Mon, 7 Mar 1994 10:06:24 GMT
From: ihnp4.ucsd.edu!usc!howland.reston.ans.net!EU.net!news.funet.fi!news.cc.tut.fi!news.cs.tut.fi![e-mail]
Subject: Battle Creek Special
To: [e-mail]

In article <2l5h88$[e-mail]> [e-mail] writes:
>What is the Battle Creek Special antenna that was used by the recent 3Y operation
>on the low bands?

BCS is vertical antenna for 40,80 and 160 meters.
It is abt 15m:s high. Bands are separated by traps.
It is full 1/4-wavelength for 40m. there is two wires on the top to make
80 and 160 also ok.
                                  *
                               *  T2
                            *     I +
                         *        I   +
                      *           I     +
                   *              I       +
                *                 T1
                                  I
                                  I
                                  I
                                  I
                ------------------I-------------------
=================================================================
= ground
I vertical part
T1 trap for 40
T2 trap for 80
+ lengthening wire for 80
* -----ii------------- 160
- radials

>
>
>                              Bob W8ERD
>
Jukka OH3NLP





--
** Jukka Salonen OH3NLP * E-mail: [e-mail] *****************************
** Addr: Sorva **************************************************************
******** 37120 Nokia ********* Too old to Rock and Roll, too young to die.***
******** Finland ************************************************************

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Date: 7 Mar 1994 18:02:03 GMT
From: ihnp4.ucsd.edu!agate!usenet.ins.cwru.edu!news1.hh.ab.com!icd.ab.com![e-mail]
Subject: Design of Cubical Quad
To: [e-mail]

quad designs in William Orr book "All about cubical quad antennas"?

Looking to build a 20M-15M-10M tri bander. Questions:

1)  What is the bandwidth of the design?  2:1? 1.5:1?

2)  Has anyone model the design? NEC wire 1.0?

3)  What is the true Front to Back ratio and Gain?

4)  Are the elements length correct?

Thanks,

Brian (N8RPA)

------------------------------

Date: 7 Mar 1994 14:07:53 GMT
From: ihnp4.ucsd.edu!library.ucla.edu!europa.eng.gtefsd.com!news.umbc.edu!haven.umd.edu!cville-srv.wam.umd.edu![e-mail]
Subject: Dipole or Vertical for DX?
To: [e-mail]

In article <[e-mail]>,
 <[e-mail]> wrote:
>Hi,
>
>    Just wanted to know if a dipole or vertical performs better for QRP DX?
>    This is on 20 meters.
>
>73 de 9V Daniel
>
I don't think anyone will really disagree - A vertical will do considerably
better than a dipole for ANY DX'ing, as long as you have a good ground plane.
The vertical gives you a lower angle of radiation (imagine a donut-shaped
emission from a dipole) than will a horizontally-mounted dipole because
a large part of the radiation travels at a low angle to the horizon - which
is exactly what you want for DX'ing.  Either mount a dipole vertically,
hung from a tree, or use a 1/4-wave section in the vertical direction,
and tie the shield of the coax to a good ground plane, like radial wires
or a chicken-wire mesh.

Scott NF3I



--
73,                            _________   _________  The
                            \ /  Long   Original
Scott Rosenfeld  Amateur Radio NF3I  Burtonsville, MD     |   Live    $5.00
  WAC-CW/SSB  WAS  DXCC - 125 QSLed on dipoles __________| Dipoles! Antenna!

------------------------------

Date: 4 Mar 94 06:26:11 GMT
From: agate!howland.reston.ans.net!torn!nott!uotcsi2![e-mail]
Subject: MFJ SWR Analyzers
To: [e-mail]

Henry B. Smith ([e-mail]) wrote:
: Is anybody familiar with either the MFJ-249 or MFJ-259 SWR analyzers?
: Can the MFJ-259 really measure feed-point resistance when it is
: inserted at the equipment end of the coax?

: A general question: Can you dependably determine the resonance of an
: antenna by looking for the lowest SWR?


I'm familiar to neither but I can tell you that you can't determine
the feed point resistance using SWR information only. With SWR you
can only determine the magnitude of the reflection coefficient. If
you wish to determine the feed-point resistance, you also need to
have the phase of the reflection coefficient at the feed point. One
of the ways of knowing the phase is through determining the position
of the first voltage minimum. I don't know if the above analyzers can
provide that. If they do, you can always find the relationship
between the position of the first voltage minimum with the reflection
coefficient phase from many antenna books.

As to your second question, the answer is generally Yes! But be careful,
the resonance is also dependent on the reactance (in fact capacitance)
resulting from the junction between the antenna and the coax. With
different junctions you have different capicitances and hence the
resonance shifts even if the antenna is the same. Examples of what
makes different junctions is different coaxial lines, different
coax connectors etc

Hassan <<[e-mail]>>

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Date: 7 Mar 1994 12:09:24 -0500
From: ihnp4.ucsd.edu!usc!elroy.jpl.nasa.gov!swrinde!emory!news-feed-1.peachnet.edu!concert!borg.cs.unc.edu![e-mail]
Subject: R5 info/part needed
To: [e-mail]

A local fellow bought a used Cushcraft R5 at a hamfest but didn't realize
until too late that the box didn't include the "MN-1 matching network".
Does anyone possibly have one of these for sale (Cushcraft wants $116)
or have info on what it is and what to substitute or how to make one ???
Any reference to a magazine article on the R5 would be appreciated.

thanks,
Nick KD4CPL
[e-mail]

------------------------------

Date: 4 Mar 94 13:44:59 GMT
From: agate!howland.reston.ans.net!cs.utexas.edu!geraldo.cc.utexas.edu!slip-2-27.ots.utexas.edu![e-mail]
Subject: Radials for rooftop antenna
To: [e-mail]

I have a Cushcraft AV3 and want to mount it on my roof. I am not sure what
to do for radials.  Cushcraft sells a radial kit which consists of 9 radials
some single some multiple wires.  It would seem possible to use 12 wires, 4
for each band covered.  Could I get by with having 4 groups of 3 wires each
cut to 1/4 wave length, running together, 3 to a group? Also what angle do
they need to slope down?  This antenna was a hamfest special and I have no
instructions as to mounting, tuning etc.  Any advise will be appreciated.

------------------------------

Date: 4 Mar 94 06:20:11 GMT
From: agate!howland.reston.ans.net!noc.near.net!news.delphi.com!BIX.com![e-mail]
Subject: Simple Signal Question
To: [e-mail]

In article <2kk57u$[e-mail]>, [e-mail] (Dane L.
Cantwell) wrote:

> A friend and I were talking about cellular phones.  He is in the market
> for one and we were talking about the merits of a "full size" phone at 3
> watts versus a portable at 0.6 watts.  It was my point that the extra
> transmission power is discounted because the signal received at tower is
> related to the square of the distance to the tower.... therefore you
> don't get anything like 5 times the range with a 3 watt model over a 0.6
> watt unit.  Is this right in theory?  How about the real world?

I have a handheld OKI 1150, one of the smaller units on the market.
I would never trade it for a car phone or bag phone or whatever.
Convenience is everything with a cellular phone.  The handheld unit
can be slipped in a back pocket or a coat pocket and goes with you
anywhere.

If you're married, you can probably identify with this:  my wife is
forever sending me to the store for things that don't exist.  She'll
tell me to get the 12oz can in the red label.  When I get to the
store, they'll have 8oz and 16oz cans in blue and green labels.  No
12oz red.  And no matter what I choose, it's going to be wrong.  No
problem:  I just phone her standing right there in the aisle.  (I
have a cellular plan up here near Boston that makes off-peak calls
like this free.)

If we go out for the evening, we give the sitter my cellular number.
No worrying about where exactly we'll go or anything like that.

Unless you really, really are convinced you're going make all your
calls from your car, where, okay, the speakerphone, etc., are useful,
you're really nuts to get anything but a handheld.

Re: signal quality, frankly, it's been my experience that if you're
in a good area, it's good, and if you're not in a good area, it's not
good.  There's precious little difference (as in, I sure can't tell
any) between what you'll hear with a good handheld vs. a regular
carphone.  My OKI works perfectly fine, for example, in the car
while I'm driving unless I'm out in a fringe area where nothing would
work anyway.

Regards,
Doug Hamilton     [e-mail]    Ph 508-358-5715
Hamilton Laboratories, 13 Old Farm Road, Wayland, MA  01778-3117

------------------------------

Date: Sat, 5 Mar 1994 20:57:25 GMT
From: ihnp4.ucsd.edu!usc!howland.reston.ans.net!pipex!uknet!brunel![e-mail]
Subject: Slim-jim dimensions?
To: [e-mail]

Hi,

I'm looking for the formulae required to produce a slim-jim. Specifically,
I'm interested in using a slim jim as an antenna for a broadcast FM receiver
using open-wire feeder for the antenna.

Any help would be appreciated.

73 Nick, G7ENS

------------------------------

Date: Mon, 7 Mar 1994 22:47:25 GMT
From: ihnp4.ucsd.edu!swrinde!cs.utexas.edu!oakhill![e-mail]
Subject: test
To: [e-mail]

testing

------------------------------

Date: Mon, 7 Mar 1994 17:47:21 +0000
From: ihnp4.ucsd.edu!usc!math.ohio-state.edu!howland.reston.ans.net!pipex!demon!vetinfo.demon.co.uk![e-mail]
Subject: ZL Special on 6m verse Yagi
To: [e-mail]

Hi folks,

Have you used a ZL Special on 6m, I am thinking of building one to replace
my 4 Element Wide Space Yagi that I am currently using.

Now the F2 prop has gone, but not forgotten, I feel now is the time to
experiment with beams on 50Mhz, as conditions should be a little more stable.

So I think I read somewhere that the ZL Special beams have better gain and
F/B ratio than a yagi with the same number of elements, and also has a shorter
boom length, is this correct?

Also I am unable at the moment to have the beam up above 30ft, and I believe
that the ZL Special design will work well at this hieght.

I have had a design for a 5 element ZL Special given to me, but would be
interested in other's espec. the 7 element version.

I also beleive that the ZL Special will be a lot broader banded than the
current 4 Element Wide Space. which would be pref. as I wish to continue
experimenting with RTTY on 6m, but the fqy is 50.600 and a little to high
for my existing beam.

I look forward to reading your comments.

CUL
--
Peter J Carr
Internet Mail Address  : [e-mail]
Packet Radio Address   : G7ETZ@GB7IMB

------------------------------

Date: 7 Mar 1994 13:56:47 -0600
From: ihnp4.ucsd.edu!swrinde!cs.utexas.edu!convex!news.utdallas.edu!corpgate!crchh327.bnr.ca![e-mail]
To: [e-mail]

References <[e-mail]>, <[e-mail]>, <[e-mail]>
Subject : Re: AEA ISOLOOP


In article <[e-mail]>, [e-mail] (Gene Marshall) writes:
|> : While the antenna was fine, we were : having no fun trying to get the
|> thing to tune using that awful set of : controls.
|>
|> Just curious: has anyone out there invested in or used the new
|> controller? You know, the one that's the same price as the antenna?

I recently picked up a used ISOLOOP with IT-1, which also included the
manual tuner.  Let me tell you, the IT-1 is AWESOME.  It makes tuning
the loop as easy as possible.  It lets you enter a freq in 1 MHz increments
from 10 to 30, it will auto-tune using either background noise or SWR
measurements, and it will quickly fine tune itself using either of the
above methods at any time by pressing a couple of buttons.  It also has about
9 memories for storing the settings for your favorite freqs.  It is even
smart enough that it always tunes from the same direction internally, so
that the butterfly capacitor is always properly aligned (no worry about
backlash in the gear).  Oh, one last thing, you can tune from 10 to 30,
and be ready to transmit in less than 5 seconds total.  Not bad, but for
around $600 total retail, it better do something!  Sorry, I only paid
$250 for both pieces...but this is definately a good option if you have
limited space.  I also have a 40M dipole in a U shape, at about the same
height (20ft above ground, in attic), and the ISOLOOP usually beats the
dipole by 2 to 4 S units in the 10-30 MHz range.  One note though: You will
still need a long wire or something similiar to scan on.  It is a little
tricky to re-tune the loop as you turn the dial...although I have become
quite skillfull at doing this...

Hope these comments help.  Although expensive, this product WORKS.  A friend
of mine has the MFJ version.  Is is similiar, and much less expensive, but
tunes much slower, and is lower quality.  Some folks have reported that the
tuner on the MFJ exposes the operator to RF in the shack, since it uses the
coax as the motor controller too.  MFJ Super High-Q loop is decent for the
price, but my friend with the 1786 wishes he had an ISOLOOP.  Also, on a
technical note: the ISOLOOP uses totally inductive coupling, i.e. the 'loop'
itself, including the outside halves of the tuning cap. are completely
electrically separate from the rest of the antenna.  The feedline is
coupled to the loop using a faraday coupling loop, which is simply a short
at DC (inner conductor connected to shield of coax.  The MFJ is different in
that the shield of the COAX is connected to the 'loop' of the loop, and the
center conducter is coupled inductively for transmitting.  They accomplish
the same thing, but do it in slightly different ways.
Both designs are very interesting.

Have fun.

|>
|> Thanks,
|> Gene
|> --
|> +----------------------------------------------------------------------------+
|> |Gene Marshall                       \-\-\           email: [e-mail] |
|> |Hewlett Packard Co., MS 42UN          |                   Tel: [phone] |
|> |Software Svcs & Tech. Division (SST)  | ___o              Fax: [phone] |
|> |11000 Wolfe Road                      L^\<._          [e-mail] |
|> |Cupertino, CA 95014                  (_)/ (_)         CompuServe: 75060,260 |
|> +----------------------------------------------------------------------------+

______________________________________________________________________
| David E. Baker  | Internet: [e-mail] (Richardson, TX, USA)   |
| IP: 47.122.65.7 | UnixID: crchh7b0 | Bell-Northern Research, Inc.  |
| Callsign: AB5PI | Packet: AB5PI@N5AUX.#DFW.TX.USA.NA | Smile! ;-)  |
| My opinions do not necessarily reflect the opinions of my employer |
|--------------------------------------------------------------------|

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End of Ham-Ant Digest V94 #58
******************************