Frank, My experience was that I had mechanic after mechanic work on eliminating my radio noise. They did the things they knew to do. Bill after bill added up to about $2k-$3k in today's money.
Finally, I found an avionics shop, bit the bullet, flew the plane there and left it. I got a call the next work day saying it was fixed. When I went to get it, he wouldn't take any money because the solution was so trivial the expert took only a few minutes to diagnose and fix the problem. (Naturally, he got LOTS of word of mouth recommendations from me.) A real avionics expert can be worth the cost even though you will probably not get a deal like mine. It can be better to pay for a real expert rather than pay for groping around attempts by non-experts. Maybe we can help. More information helps a lot. Here are a few diagnosis questions I'd think of: 1. Exactly what does that noise sound like? Slow click, very fast tick-tick-tick, buzzer, or more like random static? 2. Does it change frequency with engine speed? 3. Does it make the noise with both mags, each tested separately? (John Savot's question) 4. When the engine is running at a fair speed (i.e. 2,000 rpm), if you switch the mags to off does the noise go away instantly or does it continue for a few seconds as the engine spins down? 5. Does the handheld still have this problem with the engine running and the master switch off? 6. When you tested with the handheld, was it running on batteries or plugged into aircraft power? (If it was on airplane power, then test it on battery power with rubber ducky antenna.) This one can provide hours and hours of ?fun?! Ed
