Hi Bob,
Bonding (not grounding...) coax to the bottom of a tower helps to
divert lightning currents from the coax shield to the ground system
at the base of the tower
Bonding coax to the top of the tower helps to equalize the voltage
between the coax and the tower face. This helps to avoid pin holes
in the coax during a lightning strike.
Bonding all coax, control cables and all other external wiring to the
a ground system at the entry to your shack forces the voltages on all
of those those cables to be equal.
None of this is related to common mode suppression. That is best
accomplished by a choke near the feed point of the antenna.
73
Frank
W3LPL
From: "Bob K6ZZ" <bob.selbrede@gmail.com>
To: "topband" <topband@contesting.com>
Sent: Wednesday, March 25, 2020 10:24:11 PM
Subject: Topband: Feedline Grounding and Feedline Chokes
Folks,
I see a lot of references to grounding coaxial feedlines at the top of
towers, bottom of towers, and at house entry points. Is this purely for
static and lightening protection purposes or does it also help mitigate
Common Mode problems as well?
If feedlines are well grounded, are chokes still useful for controlling
Common Modes problems? I suspect that both can be used, and should be
used, in a well designed station.
Are there specific recommendations on the use of chokes on grounded
feedlines? Does placement matter?
Thanks, Bob K6ZZ
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