CB is interferring with scanner and radio

[thaibjj]

I jumped into my truck today crank her up then turn on my cb (it's a cobra those little black ones from walmart) I call my buddy on the cb and when I talked into the mic my voice came out of my truck's stereo speakers! The call still goes through though. When buddy answered his voice did NOT go through my trucks stereo speakers. My voice goes through the speakers when my stereo is set to tuner, cd and aux.

Then when I turned my scanner on.... When a call is coming through the scanner, if I press the mic button the call on the scanner cuts off but comes back right when I lift the button.

This all just started happening today never had this problem before. Neither the scanner nor the cb is connected to the trucks stereo. I checked all the wiring the wires that cross are the scanner's and the cb's power source. The power source for them are in no way related to the stereos. Someone please help!

[gmclam]

Have you checked the SWR of your antenna? If you are running less than 5 watts, it sounds to me like something is out of tune.

[freqs]

CB could be mounted to close to car radio and scanner .I had a 90's gm pickup that my cb would come thru the speakers as well. with the scanner the 2 antenna's could be to close .try moving the CB and antenna's first .like gmclan check that SWR .one more thing your antenna coax check that .make sure it has not come loose from the back of the CB radio or antenna mount.Check for a crack in the coax and the coax is in a straight line (no loops between cb and antenna)

[thaibjj]

thanks guys really! I tried moving the scanner and cb away from each other and made sure the coax wasn't loose... no difference. I'll have to try looking at the coax and check the SWR. I did just have a sound system put into my truck a couple days ago I'll have to make sure the guys did it right. Good thing I have the day off tomorrow.

[gmclam]

Originally Posted by thaibjj

thanks guys really! I tried moving the scanner and cb away from each other and made sure the coax wasn't loose... no difference.

After reading freqs' post, it did make me think it could some issue of inductive coupling between devices.

I did just have a sound system put into my truck a couple days ago I'll have to make sure the guys did it right.

Is the entire sound system in the trunk, or is there a long run of wires (not including speaker wires) between the trunk and the dash? Certainly a long run of wires could be inductively picking up the CB transmission. Any such long run needs to be well shielded and properly grounded.

It sounds like you have a large power amplifier in the trunk, and what is happening is that the CB's signal is getting in to the amplifier's input. That creates a whole different line of thinking than if you were coming out the speakers of a factory in-dash radio.

[Nubz]

sounds like a bad connection or bad ground someplace
i know this sounds vague but hard to tell without looking at it

[TheJerk]

Scanners are just sensitive, it will always pick up your CB...

However, the radio sounds like poorly shielded stereo equipment...poor filtering, etc.

You may not be able to cure it.

[UPMan]

Note also, that the important part to move is not the CB itself, but rather its antenna. If the antenna is near the car's and/or scanner's antenna, then interference is more likely. If the antenna is near a long wire run to either receiver (even DC power wire), that could also be a path to interference.

[kc2rgw]

I've had RFI issues getting into car stereo amps many times with many brands of amps. They are succeptible to RFI for sure. I had issues with stock CBs, but very rarely...

You could try bypass caps on the speaker outputs and/or the line level inputs. I never bothered, I just kept the stereo off when on the radio.