This static problem is really a pain. I've been trying to play @baltic_dragon's Iron Flag campaign and it's almost unusable because the instructor voice start with a small amount of static, but the the volume of the static increases with each line until the voice is almost unintelligible. I've had to turn up the font size and turn the FM radio volume almost off to just read the dialog. Hardly the immersive experience I wanted in buying the campaign....
I couldn't get voice chat PTT to help as a workaround either, but I didn't try it multiplayer in the campaign of course.
Other things that don't work:
Changing audio settings, changing frequency, cycling the radio on/off, turning off all other radios and sounds, replacing the VoiceChat static.wav file.