[Elecraft] K3 & Beringer HA400

[Steven Pituch]

Hi All,
I tried using these two items together and am getting scratchy audio in the
headphones when I speak on USB even though the monitor is set to zero.  When
I use the rear headphones out to feed the HA400 it is really bad and loud.
When I use the front headphone jack its medium loud but still not right.  It
can be heard on my transmitted audio.

I tried using a battery to power the HA400 to isolate the ground but it has
no effect.  I did the "Modification Improving the Immunity of the Rear-Panel
RS232 and Audio Connectors to RF" mod, and checked to be sure that the
"Front Panel Microphone Circuit" mod had been done at the factory.  I tried
also using RG 174 for the audio feed.  No change.  I also removed the serial
cable and had no change.

Any suggestions would be greatly appreciated as I do need to have four
headsets on the K3 for various ham demos.

72 and thanks,
Steve, W2MY