To: <topband@contesting.com>
Date: Mon, 12 May 1997 00:19:31 -0500
From: Phil Clements <philk5pc@connect.net>
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To: topband@contesting.com
Subject: Re: EMF/Lightning Protection For Preamps
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Several of you have asked what size lamp to use between the antenna
connector and the preamp board. I duplicated the circuit in my two
Yaesu FT-ONE's because of its 17 year success. I have had zero failures
so far, with lots of 160m and 80m RF appearing at the RX antenna port
during TX when using verticals for transmit and very close-by RX antennas.
The bulbs in the Yaesu are 14 volt 0.2 amp units. I was able
to purchase a supply of similar bulbs at a hobby shop with pig-tails
already installed. You just remove the bus wire running from the antenna
binding post to the circuit board with the lamp.
I recommend this mod on the ZJ boxes, even if they are not the models
with a preamp installed because the matching transformer is wound with
very small wire. The ZJ box for 80/160m, B.C. band filter, EWE antenna,
line isolator (at the coax output of the box) and 9913 coax have given
me very good results in a very noisy residential neighborhood. The EWE
system as described beats my 90' vertical consistently in the direction
it is aimed. It never did this before with preamps and filters in the
shack.
(((73)))
Phil, K5PC
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