Topband: Covered /bare antennn wire

[ZR]

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 at sbcglobal.net>
To: "Tom W8JI" <w8ji at w8ji.com>; "John Langdon" <jlangdon at outer.net>; "Bruce" 
<k1fz at myfairpoint.net>; <topband at 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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