Reports of crackle/popping sound from cobra 29

I am helping a friend get a cb setup working, I think we've decided it must be something strange with the ground / electrical. The radio will transmit crystal clear one minute, then it will be so crackle sounding you can't even understand him. My question is, what types of filters should I now install, as last resort options? I have installed many cb's in the past and never encountered this problem.



Thanks





Sent from my iPhone using Tapatalk

Reports of crackle/popping sound from cobra 29