Engine/alternator noise on radio

This is referred to as EMI (electromagnetic interference). It was a big problem back in the day when everything was analog. They used to have filters for this. I actually had a similar problem so I just bought a separate battery and hooked my radio to it. I use the cig lighter to charge the battery while driving.

 

Back in the day (!) I would use an inline noise suppressor, not sure where to find them anymore.
Have you asked on the cb radio forum? Sure those boys would know.

 

Yes I bought those at Radio Shack back then. You could find them everywhere lol.

 

Are you running a power inverter ? We found that was the issue in a Pete 387.

 

I also read about that, that there was an issue in Pete 387 about power inverter. I don't know if there have a solution for that.

 

Sine wave invertor can eliminate some or all the noise

 

Try replacing the audio cable. A broken wire can also cause the issue.

 

Check your grounding of the radio. If the grounding is good and the condition still continues the you may need to add a small bi-polar capacitor (usually 0.47 uF) between the radio's power wire and the ground wire. A good reference is http://www.dieselduck.net/machine/03 electricity/radio_interference.htm while it is oriented to marine machinery the concepts apply to your truck.