[Elecraft] K3 Hum on mic between 2 rigs

[Jim Brown]

On Thu,9/24/2015 9:48 AM, Dan Atchison via Elecraft wrote:
> I built a nice boom microphone switch to swap my Heil PR781 between my 
> K3S and my K3.  The switchbox uses XLR connectors so I can use the 
> Heil K3 "proper" cables to each rig.  I bought a regular XLR extension 
> cable for the mic to swithbox.

An important question. Is what you hear HUM (60Hz only) or BUZZ 
(harmonics of 60Hz)? It makes a VERY large difference in the cause and 
the solution.

73, Jim K9YC