[Elecraft] KPA1500 hum - problem solved

[Jim Brown]

On 4/5/2020 2:37 PM, Buck wrote:
> I would bet your coax shield is acting like a radial and bringing RF 
> back into the shack.  Need a choke.

Yes -- the clue was the info about the switch. But it also indicates a 
lack of proper bonding.

http://k9yc.com/2018Cookbook.pdf

What model of vertical? Some designs require radials, some do not.

73, Jim K9YC