Squeeling from CB

[knackered]

Question for all you experts.
I use a slip seat box as I change trucks every trip I make.
I have a Magnum S9 in the box, also a Pioneer stereo with 4, 6 x 9 speakers and one 10" subwwofer and a Pioneer 600 watt amp for the stereo.
My question is, why is it when I have the stereo on and I go to talk on the CB it squeels like a pig being castrated, now I can turn the mic gain all the way down and the squeeling stops, but I can barely be heard. Is there anything that can be done so I can use both at the same time without turning mic gain down ?
Thanks in advance.

 

[ken white]

Question for all you experts.
I use a slip seat box as I change trucks every trip I make.
I have a Magnum S9 in the box, also a Pioneer stereo with 4, 6 x 9 speakers and one 10" subwwofer and a Pioneer 600 watt amp for the stereo.
My question is, why is it when I have the stereo on and I go to talk on the CB it squeels like a pig being castrated, now I can turn the mic gain all the way down and the squeeling stops, but I can barely be heard. Is there anything that can be done so I can use both at the same time without turning mic gain down ?
Thanks in advance.

Because when you transmit, the RF signal is being coupled into the speakers wiring, which comes out the speaker and into the microphone, and then back into the CB to complete a loop. This is called positive feedback and is the principle of oscillators, hence the high frequency squeel you are hearing.

You will probably need to do some rewiring so the magnetic fields are reduced which will reduce coupling, or move the speaker/microphone location/direction so the audio signals don't couple.

Have fun.

 

[4600turbo]

Or turn off the radio while you talk on the CB!

 

[DTB Radio]

Some simple things to look at are antenna SWR, and make sure you are NOT running a 2nd CB antenna as your AM/FM antenna. Having 2 antennas on a single mount is OK as long as the AM/FM is one of those straight-whip types with no loading coil. If you use a single CB antenna into a splitter to run the AM/FM and CB, you may need to check the adjustments in the splitter. Read the manual that came with it first, or you can screw things up. Since you only get the squeal with the radio on, I suspect a poor quality design in the receiver front end of the stereo. Not much you can do there, unfortunately, but a simple coax trick might help a bit. Cut a piece of CB coax to about 7 feet, and put a connector on one end that will allow you to hook both it and the main AM/FM coax up to the AM/FM at the same time. Don't connect the other end to anything, just leave it hanging out someplace where you won't step or trip on it. (Don't coil it, either, leave it stretched out as much as possible when using the system. You can coil it for storage all you want). This will act as a filter knocking down alot of the CB signal that might be getting into the AM/FM.

 

[knackered]

Thanks DTB. I am not running any FM antenna on this stereo as I use XM all the time, but I can give your suggestion a try.
Thanks a lot

 

[Carl]

use a noise canceling mic, not a power mic

 

[knackered]

i do use a noice cancelling mic, I use an RK56