Total posts : 45366
There is an old saying which goes “it is humming because it is happy”.
I have the same problem with the SSTRAN and I think it is due to ground loops in the audio feed from my sound card. A quick fix is to turn the compression control CCW (all the way if needed). This doesn’t fix the problem but it will give a very nice hum free signal until you can locate the source of the hum.
If you still have a lot of hum after this adjustment, there is something seriously wrong with the audio circuit.
OK…here’s an edit. After I posted this I checked the compression adjustment on my tx and found that the hum is gone regardless of the setting. I now have it about half way up and the performance is super. Low volume stuff gets boosted to high levels.
I think my hum problem fixed itself! Not really. My audio feed goes to several things and I have built a parallel RCA jack manifold. It is not in a box and I think the “hot” line was touching something nearby or I had a bad cable since I have replaced a few in the circuit. Even brand new patch cables can be bad right out of the box.