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1994-11-13
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Date: Sat, 23 Apr 94 04:30:14 PDT
From: Ham-Ant Mailing List and Newsgroup <ham-ant@ucsd.edu>
Errors-To: Ham-Ant-Errors@UCSD.Edu
Reply-To: Ham-Ant@UCSD.Edu
Precedence: Bulk
Subject: Ham-Ant Digest V94 #116
To: Ham-Ant
Ham-Ant Digest Sat, 23 Apr 94 Volume 94 : Issue 116
Today's Topics:
2m/70cm on a Honda.. Which One?
Best city antenna
Calling all balun experts
Formula for determining optimum distance between elements in a Yagi beam (2 msgs)
groundplane antenna for 157.32125mhz
Is this too crazy to work!!??
Listening to shortwave in car
Slot antennas on cars?
Thanks to all who responded to Yagi element spacing question
Through-the-window on a Saturn
What are good propagation/DX programs?
Will this work??
Send Replies or notes for publication to: <Ham-Ant@UCSD.Edu>
Send subscription requests to: <Ham-Ant-REQUEST@UCSD.Edu>
Problems you can't solve otherwise to brian@ucsd.edu.
Archives of past issues of the Ham-Ant Digest are available
(by FTP only) from UCSD.Edu in directory "mailarchives/ham-ant".
We trust that readers are intelligent enough to realize that all text
herein consists of personal comments and does not represent the official
policies or positions of any party. Your mileage may vary. So there.
----------------------------------------------------------------------
Date: Thu, 21 Apr 1994 16:27:53 GMT
From: ihnp4.ucsd.edu!galaxy.ucr.edu!library.ucla.edu!europa.eng.gtefsd.com!news.umbc.edu!eff!news.kei.com!world!dts@network.ucsd.edu
Subject: 2m/70cm on a Honda.. Which One?
To: ham-ant@ucsd.edu
In article <1994Apr20.233638.5030@ccc.amdahl.com> dws30@p1dbg02cd.amdahl.com (David Sharpe) writes:
>Rumor has is keying up with some rigs will kill the computer in the car.
>I would like to know if this would be a problem with a 89 Accord. I
>would also like to know what 2m/70cm antenna and mounting seems to work
>the best. I have a FT-530 and will most likely pick up a moble, so if
>you have any helpfull hints on those I am very interested in that info
>as well.
>
> Dave Sharpe Sunnyvale Ca. DWS30@duts.ccc.amdahl.com
Experience with Hondas seems to indicate that you won't hurt the computer
in the car. The car, however, may radiate a LOT of noise into your
antenna, and from there into the radio. Some hondas are rolling wide-band
RF noise sources. (Our 88 honda has this problem, and many others have
reported the same problem).
Dan
--
---------------------------------------------------------------
Daniel Senie Internet: dts@world.std.com
Daniel Senie Consulting n1jeb@world.std.com
508-779-0439 Compuserve: 74176,1347
------------------------------
Date: 22 Apr 94 22:36:21 GMT
From: dog.ee.lbl.gov!ihnp4.ucsd.edu!library.ucla.edu!news.ucdavis.edu!chip.ucdavis.edu!ez041502@ucbvax.berkeley.edu
Subject: Best city antenna
To: ham-ant@ucsd.edu
ez041502@chip.ucdavis.edu wrote: [stuff deleted]
Fine. you people are of absolutely no help. Not one response.
I guess I'll just go back to newsgroups that are actually helpful.
Stan "Bye, Bye" Kwong
------------------------------
Date: 22 Apr 94 06:23:28 GMT
From: dog.ee.lbl.gov!agate!howland.reston.ans.net!noc.near.net!news.delphi.com!usenet@ucbvax.berkeley.edu
Subject: Calling all balun experts
To: ham-ant@ucsd.edu
Is this almost the 21st century? The best advice I get is to feel of the
baluns? Thanks, Ignacy, for the suggestion... I'm game for anything. I
applied 50w for 5 min and felt of both baluns and couldn't feel any
difference in temperature so this report is very subjective.
The Amidon voltage balun had a "solid" feel when tuning. I have an MFJ-949E
tuner and the SWR would not go below 1.4/1 but it was steady and stable
there. The MFJ current balun would go down to 1/1 but it wouldn't stay there.
It didn't deviate much, but crept up to about 1.1/1 and didn't have the
"solid" feel of the Amidon balun.
What does it all mean? My best WAG (wild ass guess) is that the Amidon
balun is doing a 4:1 transformation and the MFJ is not. The MFJ is doing
an X:1 transformation where X changes when the wind blows but the losses
in either balun are not enough to heat either one up (and therefore
neglible?) A received signal was the same signal strength either way which
tells me that there is an impedence difference, not a power difference.
So the plot thickens... at certain impedences the MFJ current balun appears
to change from 4:1 to something else... 3:1? 5:1?... The Amidon voltage
balun doesn't seem to care about the wind. A barely saturating balun might
not heat up but might change impedences rather dramatically.
Unless I see evidence to the contrary, I'm going to assume that Jerry Savek
knows what he is talking about and that super husky voltage baluns are
superior to current baluns... anybody care to comment?
slowly going crazy... KG7BK, CecilMoore@delphi.com
[A
------------------------------
Date: Thu, 21 Apr 1994 00:05:49 GMT
From: ihnp4.ucsd.edu!usc!howland.reston.ans.net!wupost!waikato!canterbury.ac.nz!news@network.ucsd.edu
Subject: Formula for determining optimum distance between elements in a Yagi beam
To: ham-ant@ucsd.edu
In article <CoIM2v.3qC@fc.hp.com> Jay Kesterson K0GU, jayk@fc.hp.com
writes:
>In article <gsladic.22.00163013@mcs.com> gsladic@mcs.com writes:
>: >Is there a formula for determining the optimum distances between
the driven
>: >element and the parasitic elements in a yagi beam?
>: >
>: >I know the driven element should be a 1/2 wavelength and the
reflector 5%
>: >longer and the director 5% shorter in a 3 element beam. How do I
determine
>: >the distance between the driven element and the parasitic
elements? What
>: >about if the yagi has more than 3 elements, say 7?
You should get a copy of the NBS paper called YAGI ANTENNA DESIGN
issued back in Dec. 1976 by Peter P. Viezbicke. It's good reading and
has lots of design info derived from expermentation, I use it all the
time, takes a bit of working out but the effort is worth it. Also the
mag. VHF Communations has good info on long Yagi design from time to
time...
*******************************************************************
Roger Corbett Phone
64-03-3642257
Education Department Fax
64-03-3642418
University of Canterbury E-Mail
R.Corbett@csc.canterbury.ac.nz
New Zealand Radio
ZL3THQ
*******************************************************************
------------------------------
Date: Thu, 21 Apr 1994 14:26:03 GMT
From: ihnp4.ucsd.edu!usc!math.ohio-state.edu!magnus.acs.ohio-state.edu!csn!col.hp.com!fc.hp.com!jayk@network.ucsd.edu
Subject: Formula for determining optimum distance between elements in a Yagi beam
To: ham-ant@ucsd.edu
Roger Corbett (R.Corbett@csc.canterbury.ac.nz) wrote:
: You should get a copy of the NBS paper called YAGI ANTENNA DESIGN
: issued back in Dec. 1976 by Peter P. Viezbicke. It's good reading and
: has lots of design info derived from expermentation, I use it all the
: time, takes a bit of working out but the effort is worth it.
Viezbicke's papers on yagi antennas do supply a lot of good data. However
the state-of-the-art has improved quite a bit in the last 18 years. There
are newer more efficient designs available.
73, Jay K0GU jayk@fc.hp.com
------------------------------
Date: Wed, 20 Apr 1994 16:38:18 GMT
From: ihnp4.ucsd.edu!library.ucla.edu!europa.eng.gtefsd.com!emory!rsiatl!ke4zv!gary@network.ucsd.edu
Subject: groundplane antenna for 157.32125mhz
To: ham-ant@ucsd.edu
In article <CoHKHC.EEJ@rahul.net> mlyon@rahul.net (Mike Lyon) writes:
>i have a scanner that i would like to build a groundplane antenna for. i
>took the bottom part of the freq range and added it to the top part of
>the freq range and averaged it and came up with the above posted freq.
>all i need to know is what is the formula to figure out the lengths of
>the poles that point downwards and upwards?
The wavelength formula is 300/MHz for a free space wavelength. Divide
the number by 4 to get the quarter wavelength dimension you need. For
the frequency you list, it would be about 0.476 meter. Now because of
end effect, the free space number will be about 5% too long, giving a
final value of about 18 inches, but that's OK because you're taking the
wrong approach to cutting a scanner antenna for the VHF HI band.
Receiving antennas work pretty well *above* the frequency for which they
are cut, but don't work at all well for frequencies *below* the frequency
for which they are cut. So you want to cut the antenna to favor the lower
part of the frequency range you wish to monitor. And for a wide receiving
range, a discone design works better than a groundplane. For your case,
a disc of 23 inches diameter over a cone 28 inches high by 32 inches across
the base should work nicely. Like so,
_______
/|\
/ | \
/ | \
/ | \
/ | \
The center conductor of the coax goes to the disk, and the shield goes
to the cone. Both disk and cone can be made of rod stock, about 8 rods
for disc and 8 more for cone should be about right. Make the disc rods
10.5 inches, and the cone rods 32 inches, each measured from tip to the
feedpoint at the hub. Note: Radio Shack sells a discone like this made
from stainless steel, very nice for scanner reception.
Gary
--
Gary Coffman KE4ZV | You make it, | gatech!wa4mei!ke4zv!gary
Destructive Testing Systems | we break it. | uunet!rsiatl!ke4zv!gary
534 Shannon Way | Guaranteed! | emory!kd4nc!ke4zv!gary
Lawrenceville, GA 30244 | |
------------------------------
Date: Wed, 20 Apr 1994 16:53:15 GMT
From: ihnp4.ucsd.edu!usc!elroy.jpl.nasa.gov!swrinde!emory!kd4nc!ke4zv!gary@network.ucsd.edu
Subject: Is this too crazy to work!!??
To: ham-ant@ucsd.edu
In article <2p22p5$rl3@vixen.cso.uiuc.edu> bpea@prairienet.org (Bruce Pea) writes:
>
>I'd like to thank everyone who took the time to send me comments
>on my chicken wire counterpoise question. Now I've got another
>question.
>
>I'm thinking of building a half-wave helically <sp> wound 160m
>vertical to stick on top of my three story house. Can I use my
>water pipes in the house as my counterpoise? What if I attached
>ground wires to the pipes and ran them out in the yard and around
>the house, would that help even more?
Yes, the more contact with Earth you can arrange, and as far out
from the antenna base as you can arrange it, the better.
>Does having the antenna three stories abouve the counterpoise make
>any difference? Is this too crazy to work? Is my ignorance obvious?
>Can you tell I JUST got my ticket and I'm going nuts trying to
>figure out what to put up :-)
Yes, yes, and yes. :-)
If you're going to do this, wind the helical halfwave about 36 feet
short and run a wire down through your house to ground level where
you can feed it directly against your ground connection. Since the
design will then be top loaded, most of the radiation will come from
the part of the antenna above the house, but your current mirror in
the Earth will be correct and symmetric. You don't want to feed it
at roof level and then run a ground connection down to Earth. That'll
be very asymmetric and inefficient.
Note: if you run much power, be prepared for your house lighting to
follow modulation, and for RFI problems with all your consumer
electronics. You're going to have a rather high RF field enveloping
the house. A loaded tower in the backyard would be better.
Gary
--
Gary Coffman KE4ZV | You make it, | gatech!wa4mei!ke4zv!gary
Destructive Testing Systems | we break it. | uunet!rsiatl!ke4zv!gary
534 Shannon Way | Guaranteed! | emory!kd4nc!ke4zv!gary
Lawrenceville, GA 30244 | |
------------------------------
Date: 21 Apr 94 23:54:06 GMT
From: agate!howland.reston.ans.net!europa.eng.gtefsd.com!news.ans.net!hp81.prod.aol.net!search01.news.aol.com!not-for-mail@ucbvax.berkeley.edu
Subject: Listening to shortwave in car
To: ham-ant@ucsd.edu
I was wondering what I could do to improve reception of shortwave in my car. I
heard the Grove No-antenna is not worth it. I now am able to directly connect
my radio to my am/fm radio antenna. It helps, but I'm sure I could do better.
I was thinking about a CB antenna with a capacitor to make it more useful for
the shortwave freq. range. Any ideas or suggestions on how to add this cap?
Hollis
Hollis113@aol.com
------------------------------
Date: Tue, 19 Apr 1994 13:07:51 -0400
From: ihnp4.ucsd.edu!usc!math.ohio-state.edu!news.acns.nwu.edu!ftpbox!mothost!lmpsbbs!NewsWatcher!user@network.ucsd.edu
Subject: Slot antennas on cars?
To: ham-ant@ucsd.edu
In article <CoGysK.7rt@hpcvsnz.cv.hp.com>, tomb@lsid.hp.com (Tom Bruhns)
wrote:
> Has anyone out there experimented with slot antennas on cars? There are
> several places you could make this work, but I was thinking of a slot
> formed from wire (or copper tape) placed at the top inside of the rear
> window. If anyone has experimented with this, I'd be interested in
> the results: impressions about performance transmitting and receiving,
> amount of RF in the passenger compartment, problems feeding the
> antenna, ... It seems like the dimensions are right for this to work
> as a "stealth" antenna on 2m and 440MHz, with vertical polarization.
>
> 73, K7ITM
It has indeed been done, not just by amateurs but also commercially.
Antenna SPecialists offered a unit fit into a rear speaker cutout which
would easily handle 100W on UHF, and others have done similar tricks on
800-1000 MHz. Several of the alphabet agencies utilize these types of
antennae in their undercover operations vehicles, making them visually
undetectable.
They still radiate some potent RF signals from 130 MHz up.
The present marketing concern is for occupants of the rear seat, who may be
subjected to significantly higher levels of EMR and H-fields than the new
OSHA/EPA regulations will allow. Secondarily, the defogger grids and now
the new conductive windshields present major obstacles to RF and thus to
the widespread use of such antenna designs for two-way operation.
--
Karl Beckman, P.E. < STUPIDITY is an elemental force for which >
Motorola Comm - Fixed Data < no earthquake is a match. -- Karl Kraus >
The statements and opinions expressed here are not those of Motorola Inc.
Motorola paid a marketing firm a huge sum of money to get their opinions;
they have made it clear that they do not wish to share those of employees.
Amateur radio WA8NVW @ K8MR.NEOH.USA.NA NavyMARS VBH @ NOGBN.NOASI
------------------------------
Date: Thu, 21 Apr 1994 13:15:16
From: ihnp4.ucsd.edu!swrinde!emory!europa.eng.gtefsd.com!news.umbc.edu!eff!news.kei.com!ddsw1!elink.pr.mcs.net!gsladic@network.ucsd.edu
Subject: Thanks to all who responded to Yagi element spacing question
To: ham-ant@ucsd.edu
My thanks to all of you who responded to my question regarding the optimum
spacing of elements is a Yagi beam. I have read all of your responses and
plan to follow up on recommendations and suggetions for further reading. When
I build the antenna and get it set up and working properly, I'll post an
update on this newsgroup about my results. Once again, thanks all.
George Sladic
--
E-mail: gsladic@mcs.com
Ham Call: <pending>
------------------------------
Date: Wed, 20 Apr 1994 16:41:51 GMT
From: ihnp4.ucsd.edu!usc!elroy.jpl.nasa.gov!swrinde!emory!kd4nc!ke4zv!gary@network.ucsd.edu
Subject: Through-the-window on a Saturn
To: ham-ant@ucsd.edu
In article <2ov1qf$g97@rcp6.elan.af.mil> edsko@ada1.elan.af.mil (Ed Skochinski) writes:
>
>Are there any Saturn owners out there who have addressed the problem? If
>I mount the antenna on top of the tinting, will this severely impact the
>antenna performance? What if I lower the antenna and have it span one of
>the rear defroster veins? Is there some strong solvent which will remove
>the tinting?
The tint is metalized, so the thru-glass antenna won't couple properly.
The defroster wires are also metal, and will disturb the thru-glass
coupling, not that plain glass would be much better mind you, thru-glass
antennas just don't work that well. Drill the hole!
Gary
--
Gary Coffman KE4ZV | You make it, | gatech!wa4mei!ke4zv!gary
Destructive Testing Systems | we break it. | uunet!rsiatl!ke4zv!gary
534 Shannon Way | Guaranteed! | emory!kd4nc!ke4zv!gary
Lawrenceville, GA 30244 | |
------------------------------
Date: 21 Apr 1994 14:35:12 GMT
From: ihnp4.ucsd.edu!usc!howland.reston.ans.net!xlink.net!news.urz.uni-heidelberg.de!rz.uni-karlsruhe.de!news.uni-stuttgart.de!smiller@network.ucsd.edu
Subject: What are good propagation/DX programs?
To: ham-ant@ucsd.edu
What's a good HF propagation forecast program for DOS? (Something
that gives you charts like you see in the ham magazines.) I was thinking
that if I had such a program and entered in current raw data myself, I'd
get more accurate charts.
While I'm at it, do you know of a DOS program that will print out a
great circle map based on any coordinates (such as my QTH)?
Please email and I'll post a follow-up if there's interest.
Many thanks & 73,
--Shannon, DL6SEU/N7APC
smiller@rus.uni-stuttgart.de
------------------------------
Date: 22 Apr 94 14:43:04 GMT
From: agate!howland.reston.ans.net!noc.near.net!mv!mv.mv.com!tetrault@ucbvax.berkeley.edu
Subject: Will this work??
To: ham-ant@ucsd.edu
To: bpea@prairienet.org
In a recent message, you wrote;
>>. My question is, instead of running 100+ individual
>>ground wires out from the base of the vertical, can I lay
>>varying lengths of chicken wire out??
>>
>>Will the chicken wire be a better ground plane than the individual
>>wires??
According to my sources random wires approaching 1/2 wave
length for the operating freq of the verticle is best. However
that being said, chicken wire will work. Bury it an inch or so
under the ground and use as much as possible.
In retrospect, I run a Butternut HF2V for 40 and 80 here and
have probably 4oo' of ground wire laid out in random lengths and
few are the 32' i/2 wl of 40m. Yet, the antenna gives me that
tiny edge in a crowded band over my G5RV when that choice piece
of DX arrives.
Go with the most you can, the more the better.
Mark
---
* UniQWK v3.3 * The Windows Mail Reader
--
-------------------------------------------------------
| Mark D. Tetrault | tetrault@mv.mv.com |
| 6 Colonial Drive | 1:132/169@fidonet.org |
| Pembroke, NH 03275 | n1men.ampr.org_44.52.7.8 |
| (603) 485-5852 | Have a Nice Day! |
-------------------------------------------------------
------------------------------
End of Ham-Ant Digest V94 #116
******************************