The T Match tuner is what sits in the house Price. The T Match feed on the
antenna is completely different, is grounded to the boom on the all metal
design and is no more prone to P-static than any other feed system.
My own yagis use a T Match from 28 to 432 MHz and work very well and without
the pattern skewing of the gamma match.
Carl
KM1H
Carl
KM1H
----- Original Message -----
From: "HAROLD SMITH JR" <w0rihps@sbcglobal.net>
To: "Tom W8JI" <w8ji@w8ji.com>; "John Langdon" <jlangdon@outer.net>; "Bruce"
<k1fz@myfairpoint.net>; <topband@contesting.com>
Sent: Friday, November 16, 2012 4:42 PM
Subject: Re: Topband: Covered /bare antennn wire
Very true Tom,
I am using on 20 meters a Telrex 20M546. The Telrex uses a T network. The T
bars
are very close to the driven element and longer than normal. They use no
series
capacitors.
Or should I say condensers as they were called when Mike Arcelino designed
the
Telrexs.
73 Price W0RI
The only noise caused by an element charging is a "pop" or arc as the
element
moves closer to air potential, until the voltage is high enough to break
down
some insulation path to earth. This is a huge problem with T network antenna
tuners that feed big antennas without a ground leak path. The antenna
trickle
charges the output capacitor (with microamperes of current) until the cap
flashes over. This sudden rings the tank with high voltage, and that blows
the
diodes in the directional coupler detector.
We certainly do not want things to charge to the point something flashes
over
and is damaged, but a ground leak does not reduce p-static (corona) noise. A
ground leak does not reduce the chance of a lightning strike, either.
Neither do
those tower whiskers (NASA has extensively tested that).
73 Tom
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Topband reflector - topband@contesting.com
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