Mike D

I was hoping there might be some cb radio gurus on the DTR that might be able to lend some advice.

I installed a Uniden PC78 with a Lil Wil antenna. I'm having a noise issue when the truck is running. All is good with the truck off. I'm pulling pwr from a cigarette lighter and have reground the cb and checked and cleaned all vehicle grounds.

Anyone help would be great.

ftltmp

Try wiring it to the battery and I think this will solve your problem, these newer vehicles dont get a good ground because of rubber isolators and frame coatings. I have mine run to the batter with a 300 watt linear and I don't have any noise. just my .02

ofcmarc

What he said. Cig lighter outlets are usually very noisy for a CB. If staight to the batery dosen't help sometimes putting a capaciter in the + wire will help smooth out noises from the other elec. systems on the vehicle.

Toy Hauler

I agree go right off the battery it will eliminate a ton of noise and do check the swr's......TOY HAULER

Mike D

Thanks everyone!

Mike D

I wired the CB straight to the battery, but yet no change.

Darn, I was hoping that would have been the fix.

jthorpe

Does it sound like a high pitched whine that corresponds to the rpm's of the vehicle or is it more of a buzzing noise? You may have to filter the wires, and also filter the antenna. What kind of CB is it? What kind of antenna are you using? How is the antenna wired? Is the radio grounded to the vehicle or directly to the battery? There are a multitude of things that could be causing this but without knowing the exact setup, it would be hard to pinpoint the issue.

Mike D

Hey Jack, It's a barefoot Uniden PC78 with weather band. The antenna is a magnet mount Wilson Lil Wil.

The noise is a whine, but does not increase with rpm. I only hear the noise when I'm receiving traffic. It's mixed in with the squelch, if that makes sense.

The radio is grounded to the vehicle.

Thanks for the help.

jthorpe

Ok, so it's not the alternator then. Does it do it with the truck running, with the truck off or both? Also, make sure you try it with truck off and no fans running such as A/C, heat etc. Let me know what you find out. If you're still hearing it, it's not a truck issue.

Mike D

I only hear it when the truck is running and I'm receiving. I've tried to run the headlight, a/c and stereo to see if I could hear a change, but the noise is constant.

When the truck is off and nothing running, I have no noise issues.

Thanks.

Mike

jthorpe

Very strange. There is something else other than the alternator doing that, but I couldn't tell you what it is unless it was the a/c or something. Have you tried it with the a/c off? Is there any other motorized device that would be giving a constant frequency like that? I know that one of the 800mhz portables I had would do that because of the circuitry in the radio, but it was consistent whether the car was on or not.

Mike D

Do you think it could be a Holley fuel pump that I'm running as a pusher?

jthorpe

It's very possible. How do you have it wired? I would try disconnecting it for a short time to see if the noise goes away. If it goes away, then you'll have to find a way to isolate the CB and the pump.

Mike D

I think the was the problem. I disconnected the pump and didn't hear the noise, just normal squelch. I had the pump grounded to the frame. Should I run a dedicated ground to the battery?

The pump is powered off a relay which is wired to the battery and gets it's signal from the power wire coming off the stock lift pump harness.

jthorpe

Good deal. So at least we got somewhere with it. I would try wiring the pump to the battery in terms of the ground. Then wire the radio like you did before and see what happens. You might have to do some experimenting.