SDS200. I had noticed a slight "hum" at beginning, during and at end of a transmission a couple of months back. But it was not that audible unless room was VERY quiet. I got this radio back in late May. But like some people since I knew it was there it was starting to bug me. Especially on those early mornings when I was up and house totally quiet. So I read up on this problem and really didnt want to tear radio apart. So as some people reported, the "mitigation" part may have shifted position over time. But my radio was mounted right where it is since day 1 and never moved. Didnt notice this little "hum" for a while after I got radio. I don't think the hum was there from when I first got radio. I wrapped AC cable where it plugs into radio a few turns around a choke but that made no difference. Then I very slightly pressed down on top front of radio during a transmission and I noticed the hum had gone away. So I thought maybe the "mitigation" part might not have good contact. So for the heck of it I wedged in a thin piece of foam between top front of radio and the wood shelf its mounted on. The foam is firm but soft and the pressure is very minimal on radio top. Hum barely audible if at all. So I also have the audio amp turning off quicker after a transmission.
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