[TowerTalk] Feedline (choke) question

[Jim Brown]

On 10/1/2025 10:46 AM, Howard Hoyt via TowerTalk wrote:
> If you look at the magnitude of CM currents using an inductive pickup on 
> feedlines as I have you will see both CM chokes and grounding can reduce 
> CM currents at the shack, but the grounding is perhaps more problematic

Mostly good observations, Howie. but problems in the shack have NOTHING 
to do with grounding, and everything to do with BONDING! Earth 
connections are about lightning safety. If chokes solve problems in the 
shack, some element of bonding is not done properly.

And when trying to measure CM on the line, we get into the obvious 
problem of doing so without disturbing the system we're trying to 
measure. Any conductors that couple to the line can do that if they are 
large enough (as a fraction of wavelength, and depending on the 
impedance of the common mode circuit at the point of measurement).

73, Jim K9YC