Topband: Ground loop isolator that passes DC

[Jim Brown]

On 12/3/2021 3:53 PM, Andrew Ikin wrote:
> I guess what Chuck means, is a Ground loop due to the antenna end of the 
> coax. screen being connected to Earth thus causing the feeder shield to 
> become a loop antenna with the ground RF return path to Rx. Hence, 
> resulting in excess noise pick-up.

A serious common mode choke at the feedpoint is critical for this, 
effectively disconnecting the coax shield from the antenna for common 
mode current. But proper grounding and bonding in the shack and 
throughout the home are critical -- a primary cause of RF in the shack 
is failure to do that.

There are differences with practice in the UK and EU with respect to 
connection of earth electrodes. This set of slides shows proper 
implementation in North America, which properly considers  both power 
and antennas with respect to lightning safety. The laws of physics don't 
change at the water's edge. :)

http://k9yc.com/GroundingAndAudio.pdf

73, Jim K9YC