Question about Cobra 29 LTD CB Radio

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Antenna light still on

I got a new radio yesterday. The SWR's were really high took it to a CB shop and they fixed her up. Set my antenna all was good till a few hours later. Now the darn red light is on when I key up. But the SWR's are low. Everyone say's they hear me fine and I can hear them but that darn red antenna light is still on.

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  • Anonymous Nov 22, 2007

    i installed the same radio in my nissan hardbody with a palomar tx 75 linear to help it out some, but even with out the linear the red light still comes on. my swr setting is close to 1.5 and all the wiring is all straight and good. what could be my problem?

  • Anonymous Feb 23, 2008

    I have the same problem to. Cobra 29 chrome. Peaked, tuned and an echo board. Swr 1.5. If I leave the radio alone and the light comes on, will it hurt anything?

  • dxdon Aug 11, 2008

    These 29LTD's have a very sensitive swr warning light circuit. When these radios are peaked, or have the power in them turned up, they have a tendency to fire the warning light even though the SWR is fine. Check your SWR with a good meter first, then, if all is fine, as suggested below, turn down the variable pot back behind the transformer that controls the light circuit. When driving an amplifier with a 29LTD, stray RF can also light up the 29LTD's antenna light, even though the SWR is fine. Check the SWR between the radio and the amp, and then, between the amp and the antenna. If both readings are below 1.5, you have nothing to worry about. Turn down the variable pot if the light bothers you. I had a modified 29LTD hooked up to a Texas Star 500, and when I spoke into the mike,(modulated), the light would flash on and off with my voice. I thought it was kinda cool. Of course, I knew my SWR readings were fine.



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The antenna warning light on the Cobra 29 LTD has a pot ( varabile resistor ) that sets the senativity of the light coming on. If you open the radio, you'le see the pot at the back of the radio. It's the last pot in the rear of the chassis Simply turn it more torward the center of the setting ( anyplace is ok as it means nothing to the preformance of the radio ). The light won't come on unless the SWR's are high. Good Luck and if I can help more, you can email me at this address or at my email address
NC Electronic
Mills, Wyoming

Posted on Jan 07, 2008

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As close to the antenna as you can, take 6 feet of extra coax and make a coil out of it about 6 to 8 wraps. Use electrical tape to hold the coil together.

It should be a uniform coil. One loop next to another.

I take a spray paint can and wrap the wire 8 times, then tape it around with electrical tape. Wrap the coil with tape. When you pull the can out the coil will stay in tact.

When you turn up the power, depending on the antenna and coax, you can get what is called common mode currents. This can sometimes trip this light. Basically stray RF travels down the outside of the cable,when normally it should stay on the inside. The coil is an RF choke. It will stop the RF from traveling down the outside of the coax. it has no effect on the signal on the inside.

This will also help keep you signal from bleeding over your car stereo and other RF problems.

Posted on Apr 24, 2009


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