[Skimmertalk] ground loop reduction?

[Mark n2qt]

I'm using cw skimmer with a non offset I/Q feed (from a Elecraft KX3).   

I have excessive ground loop noise regardless of the sound card I use
(EMU-0202 USB or Quartet).  Using transformers for ground isolation
doesn't help, in fact the ground noise is there regardless of connection
to the sound cards.   The noise sidebands go out about +/- 300 hz from
0.  

Normally the ground noise is offset from the signal and hasn't bothered
me when using an LP-PAN (6khz offset) or Softrock (23Khz offset) but 
with the kx3 it's a real annoyance since it's so close to the desired. 

Looking for positive experiences on fixing this....

Mark n2qt