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minigfather 01-05-2011 08:45 PM

Engine/Ignition noise coming out of CB??
Im a noob to CB's and have never talked or owned one before. So bear w/ me please. My searches on here came up w/ nothing....

Well i just got done installing my CB radio (Cobra 19 Ultra III). I mounted it in my center console. I have it wired to my battery w/ it grounded to bare metal of the tub below the center console. I have a 18' coax (recommended by Firestik). I made my own mount for between the tail light and the tub (kinda like the tera-flex mount). I have a 3' Firestik w/ the tunable tip.

I still need to tune it in. I turned it on to tune it in my drive way and it was quiet. So I went to drive down the street to test it out and test it closer to the interstate. When i started it up there was a loud noise coming out of the CB. I had my heater on and it was really loud. I turned the heater off and it got quiet but i could still hear a whining like engine noise. From installing stereo's i know you can get engine noise from a poor ground. I checked the ground and all is good.

Sorry for the long post but i tried to give as much info as possible to get the best answer possible.

Thanks to anyone that answers in advance...

captgentry 01-06-2011 08:50 AM

What you're hearing is called signal noise. It's the "radio waves" that eminate from all the elictic things in your jeep. For instance the electic motor that runs your heater makes alot of signal noise.

The way I fix it is to limit the legth of wires I use for my radio and make sure the antenna wire and power wires are really mounted well.

The first thing you need to do is check which part of your CB is getting the noise.
1. If you have a PA wire, unplug that and listen for the noise.
2. Unplug the antenna wire (DO NOT KEY YOUR MIC!!) and listen for the noise.
3. unplug the power cord and listen for the noise( just kidding)
3. Take another set of power wires (12v and ground)and mount those into the fuse box out under the hood or directly to the battery. listen for the noise.
4 Take off that temprary ground connected to your fuse box or battery and use the one you have mounted to the bare metal of the tub below the center console.

Odds are, if it's not the antenna wire it's that ground.

If it is the antenna you might look at where it's routed. Is it near a heater blower? running it through the dash will take it close to lots of noise generators. Make sure the outer part of your coaxial cable is grouned too. Although I think if you have it plugged into the radio it should be the same as the ground in your power wires.

if it's the power lines shortening them as much as possible is good. Other than that you may need to get an RF Choke. I'm sure radio shack has them. I'm not sure what other people do.

Anyway.. Good luck. :)

minigfather 01-06-2011 08:01 PM

well if a wire running near the heater blower is the cause then its prob my power wire. it runs under the console, under the carpet, and right up behind the blower motor then through the fire wall...

guess ill try to route it another way when im off next week...

thanks for the reply...any other answers or suggestions will be greatly appreciated...

captgentry 01-06-2011 08:23 PM

Run a temporary ground and 12v wire outside the jeep and see what you hear.

minigfather 01-06-2011 09:02 PM

will do thanks again...ill let ya know what happens...

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