Until recently, I only ran 100 watts maximum power, but I did purchase an Ameritron ALS-600 amplifier to help me mostly on lower band SSB. I was using the rig today and testing out my new Heil 781 mike that I am using to replace my ICOM hand mike. And we were testing various settings on the rigs bass and treble transmit controls.
During the test the other stations suddenly noticed rather severe RFI feedback. I switched back to the old mike but the problem was still there. Having had a lot of problems in the past, I knew that this was likely due to RF getting into my digital control or audio lines from the computer sound card to the rig. Turning off the amplifier did stop the RFI, so it is apparently due to the increased RF. Also, after unplugging the audio line in and out to the ICOM 756 Pro 2, which is via a DIN plug on the back of the rig, the problem went away. Even with the amplifier running at full power. The CI-V was still connected. I still can not explain why no one noticed the problem earlier as they were critiquing my audio and would have noticed it. On both my CI-V and my audio lines I have about 20 turns of the cables around their own 1/2" x 7" ferrite rod which has a mu of 125. This was the way that I found would externally remove RF flowing on the outside of cables. For those of you who run power, even if not for digital modes but for other modes and have the connections left in place on the rig, how are you able to reduce or eliminate RF feedback in your audio lines? I have 1:1 transformers in line, no other chokes or bypass capacitors. 73, Rick, KV9U
