Weird electrical interference while installing CB

Ok, so I'm trying to put in a CB. Got it wired in fine, when the ignition's in ACC i can get signal, transmit to other people, the thing works fine. Whenever the key's turned to ON, much less when it's started, I get _really_ bad buzzing. Related weird side-effect: the sound from the buzzer under the dashboard is being transmitted through the CB's speaker.

Tried running the radio with a wire straight to the battery - no change at all, even to the buzzer-sound deal. Pulled out all the under-dash fuses, the noise went down a little but not much. As long as the Jeep's hooked to the battery, it's got interference, and a lot of it.

I keep wanting to say it's electrical and possibly related to a ground-loop problem I still have when trying to connect devices other than my in-dash CD player to the speaker amplifier, but 1. I disconnected the amplifier entirely just to make sure it wasn't the culprit, and 2. how can there be a loop when I run a direct line straight to the battery?

Anybody have any ideas?

Go to Radio shack and get a "hash" filter for the power. It consists of an inductor and a capacitor. That should take care of it.

If you want to mail order a good one, check here.

http://www.partsexpress.com/pe/showdetl.cfm?&DID=7&Partnumber=265-030

I am assuming that you only ran the + wire directly to the battery. You should be running both + and GROUND directly to the battery.

You may still require the hash filter. I have direct battery power connections for my 'audio' devices -- and I still have noise issues.

I had to replace the ignition coil on mine to eliminate interference with the CB, FM radio and the garage door opener.

Actually, I just ran ground first, that didn't do much, so I tried running a wire for power as well and... no change. I'll try a filter tomorrow, can't hurt anything.

One other thing to check is to make sure your antenna is mounted properly. Some need to be grounded as they work in a loop, others can't be grounded or they will pick up any and all interferance.

I have a K40 that needs to be grounded and when I first installed it, any noise my XJ made came through the CB speaker. After I re-mounted it, properly this time, the noise went away. :doh:

Of course, adding the noise filter won't hurt any. It'll help if anything.

I don't know if this has anything to do with CB radio operation, but the stock stereo in my '87 does that same thing when you listen to FM stations. I thought it was just the stock radio going out, as soon as you got outside of town and the signal weakened, you would get interference (like screeching) so bad you couldn't listen. Then like your CB, I noticed that it only happened when the key was in the 'on' position. Key at 'accessory', radio reception perfect, turn to 'on', screeech!! Asked the dealer and there is a bulletin (at least on my '87) for this. The interference comes from the ECU and they have an updated ECU to prevent this. But at $600 for the part, AM works fine for me outside the city!! If your CB is mounted close to the ECU, you might try changing the location to see if the interference changes.