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[TowerTalk] Fwd: grounding bulkhead

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Subject: [TowerTalk] Fwd: grounding bulkhead
From: (L. B. Cebik)
Date: Fri, 14 Nov 1997 07:19:48 -0500 (EST)
I have used bulkheads at several positions in the antenna feedline chains 
without problems for years, although I do not have many antennas up.  On
is near the top of the tower, where the coax shield and the tower leg are
now one (with a choke balun to the antenna.  Another is in the shack,
where all feedlines (when connected) have a common plate that also is part
of the equipment master ground buss and the anchor point for the ground to
earth outside.

I suspect that problems occur with bulkheads when RF travels on the
outside of the lines and thus finds other non-grounded paths.  Good
isolation and good grounding technique usually solve problems.  Also a
good antenna switch to ground unused antennas.  Directing RF from the
active antenna to another antenna close by can induce RF in it.  Hence, I
normally disconnect antennas not in use and ground them directly to the
earth ground line.  I only keep connected to a feedline switch (that
grounds the non-selected positions) only those antennas I might use during
a session.  Have had no detectable problems with antenna performance or RF
in the shack.

I use other means to protect all when the station is not in use.

Hope these notes are useful.



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