LC,
I'm not answering for 'freecell', but I think his reply means that the 'cure' is eliminating ground loops. And, that's true, if you can.
The problem is that there are ground loops -possible- if there are more than one connection between any two things. Since it's almost impossible to eliminate all of those multiple connections and still have an operating system, the best you can do is to reduce any unwanted results. That 'reduction' isn't limited to only one route, eliminating the loop entirely. Shielding, isolation, filtering, etc, all help with that. All of those things don't mean being done only to the radio string of equipment. It means also being done to the other stuff around that equipment that -might- be causing part of the problem. Oh @#|+, lots more work, huh? 'Fraid so.
Not having ever been in your particular situation before, I don't have an absolute answer, wish I did (not really, who wants to go through that, right?). The first step is to eliminate what you can. The second step is to reduce power till it isn't bothering whatever is being bothered. Not enough power left to be usable? Go back to step one again. Repeat as necessary.
Will you eventually 'cure' it? Probably. If not, a very large hammer does wonders in making you feel better, the satisfaction in teaching that sorry @#$%$# that you're the boss, you know? That's the last resort, don't get too much in a hurry to use it.
Good luck.
- 'Doc
Five gallon bucket of torroids and ceramic capacitors. They come in very handy.
