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940210.txt
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1994-11-13
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Date: Mon, 4 Jul 94 04:30:12 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 #210
To: Ham-Ant
Ham-Ant Digest Mon, 4 Jul 94 Volume 94 : Issue 210
Today's Topics:
A Question on Yagi's.
DB .vs. Celwave
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: Sun, 3 Jul 94 11:27:00 -0500
From: ihnp4.ucsd.edu!dog.ee.lbl.gov!agate!iat.holonet.net!wwswinc!art.harris@network.ucsd.edu
Subject: A Question on Yagi's.
To: ham-ant@ucsd.edu
In <2ui2la$p6k@proffa.cc.tut.fi>, Paul Keinanen
<Paul.Keinanen@Telebox.Mailnet.fi> replied to:
Jon Tara (jtara@cts.com)
>Are the FM transmitters really circularly polarized ? I have only heard
>of circular polarized TV-transmitter tests in urban areas to reduce ghosts.
>Assuming that a specific FM-transmitter is either horisontally or
>vertically polarized, find out what your transmitter is using and
>orientate your antenna acordingly. There is no point of using circular
>polarisation if you want to receive a single station.
FM broadcasters in the US do NOT use circular polarization; however,
they do split their power equally into horizontal and vertical
components. The purpose is to serve people listening at home using
horizontal antennas, and people listening in their cars with vertical
antennas. Cross-polarization between receive and transmit antennas would
cause up to 20 db of signal loss.
Art, N2AH
Art.Harris@Woodybbs.com
------------------------------
Date: Sun, 3 Jul 1994 06:07:10
From: ihnp4.ucsd.edu!swrinde!gatech!udel!news2.sprintlink.net!news.sprintlink.net!nwnexus!olympus.net!olympus.net!vaughnwt@network.ucsd.edu
Subject: DB .vs. Celwave
To: ham-ant@ucsd.edu
> A few weeks ago I requested comments reqarding dual-band antennas for
>repeater usage on repeaters in very harsh environments. The results of that
>survey lead me to the conclusion that no suitable dual-band antenna exists
>for longevity in harsh environments.
> The time has come for our ham club to replace our repeater antennas
>(after 15 years of service, current antennas are both db-220 and
>phelps-dodge super-stationmaster). We are again discussing the db products
>4 bay vs the Celwave PD-200 antennas (VHF 146 range). My local enquires and
>combined experiences have taugh me that the 4 bay (or more) antennas work
>very well, but need frequent cleaning (yearly). The phelps-dodge antennas
>seem to be more reliable over years of neglect. We would like to make a
>good decision.
>Has anyone else traveled this path that could offer some opinions?
>I'd also appreciate comments from users of small phased beam arrays for
>repeater antennas (what type of beams, how many, what pattern you were
>trying to achieve, etc.,etc.)
>Thanks
>Terry Bartholomew NQ4Y
Terry, I have never put up a amateur repeater antenna. All of my experience
has been commercial. I suppose you know phelps dodge was bought by Celwave a
few years back. In my experience once you put up the celwave your job is over.
Land mobile apps do not seem to effect these pups. I have seen these things
picked up out of the wreckage of fallen towers and put back in service with no
subsequent problems. In the marine service they last a long time, how long? I
don't know I have never had the oppurtunity to change one. I did change one
once but I was wrong and it wasn't the antenna.(blush) I have not had very
much luck with the db products steer away from them. Thats all.
William Vaughn vaughnwt@olympus.net "Just plain Bill."
------------------------------
End of Ham-Ant Digest V94 #210
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