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[TenTec] Front End Protection

To: <tentec@contesting.com>
Subject: [TenTec] Front End Protection
From: geraldj@ames.net (Dr. Gerald N. Johnson, P.E.)
Date: Mon, 12 Oct 1998 11:31:41 -0500
Protecting a front end is tough. A quarter wave shorted stub on that T
would be more effective for static. An RF choke should work though it
won't take a direct hit. The coax may not survive a direct hit.

Silicon diodes help, two in parallel, one each polarity. But can be the
source of unwanted intermod and TVI.

I keep separate ground systems for antennas and house. They are only
connected when there's no storms about. I don't connect them when the
antenna might get hit. I've been hit with them almost disconnected
(significant air gap between them is important for isolate, at least a
foot) and the effects on the power wiring was random and sometime as
distant from the antenna leads as possible.

Probably 1k wire wound across the antenna connection wouldn't absorb
much power and being inductive would absorb less transmit power and
would take pretty good care of static build ups. Better than 100K. Well,
1K would take 5 watts out of 100 at 50 ohms. Not detectable away from
the power meter especially at the other end of a path. Would increase
SWR slightly changing the 50 ohm load down a little. Perhaps 2K would be
a workable compromise.

73, Jerry, K0CQ

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