Walter Blanchard wrote:

Apologise for this not being on the main thread, but:
Can anyone tell me how to get rid of mains hum on soundcards?
[...]

Walter,
   do those lines disappear if you switch off the RX ?
Even if they are not affected by the radio volume setting, they
could indicate some residual AC on the DC power that
supplies the final audio amplifier of the RX.
If they persist even with the radio power off, then the hum is
picked up somehow by the cable, otherwise the radio is
the cuplrit.

73  Alberto  I2PHD
.