So I've got my Cobra and Firestik installed. I've tuned it with an SWR meter and I'm between 1.0 and 1.4 on all channels. I can transmit and receive fine but the only problem I am having is a very high level of noise/static in the system when the truck is running. When the truck is off or idling, I get static on 2/6 bars on the signal meter (normal). When the truck is on and under load I am getting 4-5/6 bars, making it so that only the very strongest signals can come through clearly. With the engine under load, I have to squelch almost 75% to stop the noise, which of course allows very few signals through.

So here is my setup to answer as a precursor...
- Radio wired into cigarette lighter positive line, grounded to seat bolt, seat bolt grounded to unpainted frame.
- Antenna mount grounded directly to unpainted section of frame (also contacts unpainted section of body)

My only thoughts at this point is that both of these grounds do contact the body at some point (the cb through the seat bolt and the antenna mount through the unpainted area where it is mounted)... perhaps the body has a band ground? Is it possible for the ground to be bad enough that the frame is transmitting interference?

Any help here would be greatly appreciated... thanks!

Here is a pic that might help:

 

wiring your cb into your cig lighter power lead is one of your problems. Run the positive and negative directly to the battery and it will prob eliminate a lot of the noise your hearing. if that doesnt help then try an inline filter

 

Also, you might want to look into different spark plug wires. But even with the wires you have, a filter should work.

 

On my '85, I eliminated the ignition noise by two things.

1. Run power (fused) and ground wires from the battery, twisted together as they run back to the cab. Those wires feed only the CB, CD player and regular radio. Wires run away from igintion wires.

2. Install a noise filter inside the cab, before the power wires run to the radio.

The real key is to minimize ground loops. By having the CB ground wire up at the battery, there can be no difference in ground voltage that you may see with an in-cab ground point.

Also, if the above don't work, it may be the CB itself. I had one cheap CB that was noisy no matter how you set it up with the engine running. I finally moved that to my VW diesel where it worked fine (no iginition noise in a diesel). However, it was interesting that that CB would get noisy if a gas engine vehicle pulled up next to me at a stop light. So it must have just been a poorly shileded radio.