Hello all, maybe someone can shead some light for me on my problem, I have a Cobra 29ltd classic side mike, has swing mod, mosfet mod 520n with companion part, all of a sudden it started a growl when I start talking, same on pa mode I key the mike and soon as I give it audio it starts a crazy loud buzzing sound from the external speaker, like something overloaded ?? unkey and key up it's gone until i talk into the mike then same buzz, i tried 3 different microphones, swr is 1.08, it does the same in my mobile when i put it in my the truck, was working good up until now, anyone can help me figure this out I would greatly appreciate any info thank you