Frank:: Aircraft present an extremely hostile environment to adequate radio reception. The abundance of radio noise that seems to be leaking from your engine compartment can be traced to several clues already afforded.
I would suspect the bonding cables between the engine mounts and the airframe are either in poor condition, frayed, or non-existant. I would suggest to replace the line filters between the generator armature wire and the voltage regulator connection. (Capacitor) I would suggest observing the coaxial connection grounding at the antenna termination for some corrosion, and lastly I would probably replace the ignition wireing. Wayne
