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Comander · 01-12-2012, 03:57 PM

I bought 2 CB Radios, they both are Galaxy model dx- 959 CB`s and I also got 2 Wilson Mag mount antennas.
This worked fine for my Suzuki that I pull around but on the Motor Home it makes a noise like a pig squealing sometimes when my wife is talking to me that is very annoying.
I have asked this question on another RV forum, so it might help to say that It is a old 1976 commander RV and the antenna is stuck on a metal plate on top of the RV.
I did run a wire ( as was suggested by some one) from the plate , along the rear ladder and grounded it to the bumper.
I have now been told that I need to run a wire from the mounting bracket of the radio to the engine...I am not so sure about this because the dash were it is mounted is metal already.
I have noticed that if I turn the "power" knob on the radio down to less than half, this stops the noise but it also reduces the range that she can talk to me.
Any Ideas Guys?
Thanks

Wizard · 01-12-2012, 05:03 PM

Welcome to the forum.

Not sure about those radio's but on most, the power knob also controls the volume. The squelch knob should be adjusted to a position that the noise just stops. Turning the squelch all the way down can help bring in a distant station but leaving it that way can be very annoying.

All CB radio's should pick up noise with the squelch turned down, just a nature of the beast.

BryanL · 01-12-2012, 05:52 PM

pig squeal like?

does it change with engine RPM or anything else you can control in either pitch or volume? Make noise with the engine off? Is there a light or a gadget that you can turn on and off to change the noise?

Have a good surface for your mag mount to grab onto?

Where do you take your power for the CB from?

If you're going to run any kind of wires, run them from the CB directly to the battery, both + and - (don't use chassis for power ground return). Often the house battery makes a good supply point.

Do make sure the coax and connectors for the antenna are in good shape and not loose.

The key issue on noise is to figure out where it comes from. Then you can tackle either the source or its path to the radio.

re: "I have noticed that if I turn the "power" knob on the radio down to less than half, this stops the noise but it also reduces the range that she can talk to me." -- things like this might also be a problem with the radio but it sounds as if you are getting some feedback of some sort.

wa8yxm · 01-12-2012, 06:34 PM

Sounds like alternator whine to me too. Or perhaps one other problem.

It might be the car's system though, generally the radio pulls more current when transmitting and this will increase the alternator whine.

Now, from the sounds of it the metal plate on the roof is only "Grtounded" via the antenna, This is not a problem. You must have a ground connection on the radio, (DC at least) or it would not work.. YOU could try a ground strap. not to the engine but to a handy point on the frame under the dash. But I do not think it will help. Use fairly heavy wire. The problem is, if you have more than one ground, you can set u what is called a ground loop. and that, too, can cause issues.]

The other thing is the mic gain if the radio is adjhustable.. If it's too high bad things happen, but not, normally, a pig squeal.

There are other possible issues too, Mag mounts are not the greatest at HF frequencies, they do not really shine till you get to VHF or higher.

Comander · 01-13-2012, 12:35 PM

Quote:

The problem is, if you have more than one ground, you can set u what is called a ground loop. and that, too, can cause issues.]

Thank you.
After I read this, I went out this morning and removed the wire that was running from the plate that the antenna was stuck on to the bumper.
I had her get in the little Suzuki and now it works fine, I can increase the power adjustment full on with no more noise.
This must have been the ground loop thing you talked about making it do that.
This is great because we have found these radios to be very handy to use in places were our cell phones will not work
Again Thank you.

wa8yxm · 01-13-2012, 06:32 PM

Glad we could be of help. Ground loops are kind of rare because for it to be a problem the wire has to be a specific length or an exact multiple (and I think only even multiples either that or odd ones) but it appears you found one.

They are more common in ham radios because .... Well, we use a rather large range of wavelengths.. For example I have one radio in this motor home that can do everything from 150 Meters (Just above the AM broadcast band or about 1.5 MHZ) to 70 CM (44x MHZ) and in fact if I added the "extended" module would go to 1.2 GIG (Microwave) And that is just one box. I have four working ham radios in this house. The rest are not so flexible though.

CB is one band (11 meters pr 27x. MHZ. so it's much harder to hit a magic length.