CB squeal during transmit


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CB squeal during transmit

Postby coolhandsbob » Wed Oct 03, 2012 12:22 am



I Just bought this bike its a 2000 and I am having a CB issue and I was hoping someone might point me in the right direction . As soon as I key the mike I get a squeal which can be heard coming from the area of the dash and it is transmitted as well. I can transmit but it is not good because of this squeal. I can receive fine and intercom works fine . I just hate the thought of taking it to a repair shop with the prices they charge today.


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Re: CB squeal during transmit

Postby WingAdmin » Wed Oct 03, 2012 12:46 am

When a CB squeals during transmit, it is feeding back RF. Normally, the transmitter portion of the CB, which is shielded inside the CB itself, sends the RF signal it is transmitting down shielded coax wire to the antenna, where the signal radiates out into the air.

If the antenna is too close to the CB transmitter, the RF signal being radiated by the antenna overloads the audio portion of the CB, and a feedback loop is established - the antenna radiates a signal, which is picked up by the audio portion of the CB, which then transmits that signal, which is radiated by the antenna, and the cycle repeats. This causes the loud squeal.

There are other things that can cause the problem than the location of the antenna. The shielded coax wire that carries the signal to the antenna is damaged, so that the RF signal can leak out close to the CB. The coax could have a short, which shorts the signal-carrying core of the coax to the shield.

Other aspects of the CB which require shielding, such as the microphone wire can also be at fault. If the shielding on the microphone or its wire is faulty, it can pick up RF from the antenna. You can rule this out by unplugging your headset and seeing if the problem still occurs.

Sometimes the wiring supplying power to the CB acts as an antenna, receiving RF from the CB antenna, and feeding it back into the CB, where it leaks into the audio circuitry.

Try plugging a different antenna into the CB and see if that makes any difference. If it still happens, and you're fairly sure the problem is with the CB itself, then you can send it to Sierra Electronics, who will fix it for a flat $100 fee.
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Re: CB squeal during transmit

Postby Sempai » Wed Oct 03, 2012 11:40 am

WingAdmin wrote:...Sierra Electronics, who will fix it for a flat $100 fee.

This seems like some VERY GOOD information to know. Any chance you can post some contact info for Sierra?
Keep the rubber side down.
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Re: CB squeal during transmit

Postby WingAdmin » Wed Oct 03, 2012 4:04 pm

Sempai wrote:
WingAdmin wrote:...Sierra Electronics, who will fix it for a flat $100 fee.

This seems like some VERY GOOD information to know. Any chance you can post some contact info for Sierra?


I can do better than that: Check them out here: http://goldwingdocs.com/Vendors/Sierra-Electronics_900
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1998 XV250 Virago (sold)
2007 Aspen Sentry Trailer

Re: CB squeal during transmit

Postby coolhandsbob » Thu Oct 04, 2012 10:08 pm

I found my problem the guy i bought the bike from added a extra fuse box by the battery and switchs for auxillary things like fog light , ring of fire and ran all the connections and wiring thru the area below the left side pocket . the rubber holder for the audio cable can off so this cable was running really close to that compartment . As soon as I moved this audio cable away from this location my noise went away . Thanks for you assistance Wing Admin
coolhandsbob
 
Posts: 23
Joined: Thu Aug 04, 2011 7:13 pm
Location: Springbrook Ontario Canada
Motorcycle: 2000 GL1500 Aspencade with Voyager Conversion Kit

Re: CB squeal during transmit

Postby WingAdmin » Sun Oct 07, 2012 11:18 am

coolhandsbob wrote:I found my problem the guy i bought the bike from added a extra fuse box by the battery and switchs for auxillary things like fog light , ring of fire and ran all the connections and wiring thru the area below the left side pocket . the rubber holder for the audio cable can off so this cable was running really close to that compartment . As soon as I moved this audio cable away from this location my noise went away . Thanks for you assistance Wing Admin


OK, so there was your issue - the wiring added to the bike was acting as a big antenna. When you transmitted, your CB antenna was transmitting RF, that RF was being picked up by the wiring added to the bike, and because it was so close to your audio cable, the audio cable didn't have enough shielding to protect it against the level of RF being injected by the "antenna" close by it. Moving the cable away solved your problem.


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1998 XV250 Virago (sold)
2007 Aspen Sentry Trailer


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