<div class="plainMail">Inserting a tee connector in an arbitrary point on a
transmission line with an open or short circuited stub to obtain an acceptable
reduction in the VSWR on the line is next to impossible and is typically an
exercise in futility (which you apparently have learned).<BR><BR>The only way
to guarantee having a substantial reduction in VSWR is to first measure the
Z=R+/-jX at the connector, plot the measured R+/-jX on a Smith Chart or into a
Smith Chart computer program, determine if there needs to be a modification in
the line length and then add a Tee adapter with a shorted or open circuit stub
of a length indicated by the Smith Chart. This is not a simple or easy process
for the uninitiated user.<BR><BR>Allan Crites wa9zzu<BR><BR><BR><BR>---
On Sat, 5/8/10, WA3GIN <<a ymailto="mailto:[email protected]";
href="/mc/[email protected]">[email protected]</a>>
wrote:<BR><BR>> From: WA3GIN <<a
ymailto="mailto:[email protected]";
href="/mc/[email protected]">[email protected]</a>><BR>>
Subject: [Repeater-Builder] Commercial VHF antenna on 2m<BR>> To: <a
ymailto="mailto:[email protected]";
href="/mc/[email protected]">[email protected]</a><BR>>
Date: Saturday, May 8, 2010, 11:13 PM<BR>> <BR>> <BR>> <BR>>
<BR>> <BR>> <BR>> <BR>> <BR>> <BR>> <BR>> <BR>>
<BR>> <BR>> <BR>> <BR>> <BR>> <BR>> <BR>>
<BR>> <BR>> <BR>> <BR>>
<BR>> <BR>>
<BR>> <BR>> <BR>>
<BR>> Hi folks,<BR>> <BR>> Several weeks ago I posed<BR>> the
question of using a <BR>> Commercial VHF antenna that was resonant on 154Mhz
on<BR>> 146.745Mhz. We tried <BR>> it
today. The SWR was a bit over 2:1 on the repeater freq.<BR>> We installed a
T <BR>> connector after the cans and used an open stub to try to<BR>>
match the line...got it <BR>> down to 1.5:1, wouldn't go any lower. <BR>>
<BR>> We think the height of the<BR>> antenna makes up for <BR>> what
we suspect is a lot of loss in the antenna. The<BR>> previous location of
the <BR>> repeater antenna was 100ft ASL and this location is 525ft<BR>>
ASL. Maybe one day <BR>> we'll get a chance to retune the four
dipole<BR>> antenna.<BR>> <BR>> Thanks to all that<BR>> provided
ideas for this <BR>> project.<BR>> <BR>> 73,<BR>> dave<BR>>
wa3gin<BR>> <BR>> <BR>> <BR>>
<BR>> <BR>> <BR>>
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<BR>> <BR>> <BR>> <BR>><BR></div>
