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.
-73-
LB, W4RNL
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