CB Radio Help

[1967 TLC]

I am installing a CB radio into my FJ-60 and I have run into a problem. When ever I key the CB mike, the door speakers give major feedback. If I leave the mike keyed for longer than just a moment, it will also screech.

I first hooked up the CB radio’s power line to the cigarette lighter and the ground to the cigarette lighter’s ground wire. I have also connected directly to the battery to see if it made a difference. Nope.

I have a music amplifier hooked up to the speakers with the power wire hooked to the battery. A small wire is hooked up to the ignition which turns on the amp when the ignition key is turned on. When I remove the amp from the equation, the CB works just fine with no feedback.

How do I get around this problem without losing either the CB or the Amp? Or What have I done wrong?

Thanks for any help!

[Mark W]

doesn't sound lke you've done anything wrong. The amp is just picking up RF interference from the CB.

You might solve the problem by relocating the amp and CB further away from each other. Keep the antenna leads away from the amp too.

The problem may be the CB. Try another to see if it creates the same interference.


Mark...

[1967 TLC]

Thanks for the reply Mark.

I have been experimenting since I first posted and have found that my CB antenna path was following all the speaker wires between the amp (under the back seat) and the dash board where the music radio is. I moved the antenna away from all the speaker wires and the feedback almost stopped or at least was tolerable. Of course I now need to find a path other than over the back seat and between the front seats!

The radio I bought is a Uniden 520 that fits in the dash pocket. The CB antenna is a cheap magnetic mount. Would buying a higher quality antenna & wire help solve the problem? I.e.: Better shielding. I like the original path of the wire because it was well hidden.

[brew8]

Radio antennas when used with transmitters have an electrical field as well as an RF field, the electrical is near in so it's what is affecting your stereo, it expands at an audio rate because it's an AM radio, you need a good ground at the end of the coax to reduce the induction in your amp and it's leads, a magnetic mount does not usually have a good ground at the antenna because of paint or whatever, maybe just corrosion between the mount and the metal. The better the quality of the coax and the better the ground and the better the forward to reflected power of the system the less interference between the two devices. Also moving the wires helps, slight twists in the speaker and power wires will help as well, reduces induction.The goal is to have all the power from the radio transmitted into the air anything that is out of order in the antenna system reduces that effective radiated power.

[1967 TLC]

Originally Posted by brew8

Radio antennas wnen used with transmitters have an electrical field as well as an RF field, the electrical is near in so it's what is affecting your stereo, it expands at an audio rate because it's an AM radio, you need a good ground at the end of the coax to reduce the induction in your amp, a magnetic mount does not usually have a good ground at the antenna because of paint or whatever, maybe just corrosion between the mount and the metal. T

I think you are right. I have already removed the mag antenna. I'm going to pay a bit more attention to the mount and wire.

I just wanted to throw a quick system together, but looks like that has come around to bit me!