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.selbr...@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 _________________ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector _________________ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector