Question about Cobra 29 LTD CB Radio

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CB Radio has red light on Rx and red light on antenna, how do I fix that problem? I don't remember how to adjust my CB right, no longer have the manual for it. Its a Cobra 29 "Dale EarnHart Jr. " collection CB. THx

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The red light on rx is fine, it's supposed to change from green to red. The red light on your antenna means you have a swr issue, something in your antenna system is not right. You need to go to a reputable CB shop and have them check your swr.

Posted on Aug 09, 2010

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Red lights come on tx n rx and antenna come on when I key up the cb radio and the swr meter doesn't move


if a mod has been done to the cobra 29 (all 29,s)the light will come on just find vr6 audio the radio as it comes on adjust vr6 untill it goes away,,,,always trust your watt meter(s.w.r scale)over the flashing light its really easy to do it beats paying a shop $10-$15

Jan 13, 2013 | Cobra 29 LTD CB Radio

1 Answer

Just bought a cobra ltd crome ive mounted every thing how to i clibrate it with my attenna? when i key up both rx/tx and ant lights up red?????


This is a common misunderstanding when it comes to communications equipment. You don't tune the antenna to the radio, but rather you tune the antenna to the vehicle. the vehicle is the ground plane for your antenna system.

With that said You will need an SWR Meter between your antenna and Radio. follow the instructions for your meter for calibrating the meter and follow the instructions for your antenna for adjusting the length.

Jul 14, 2011 | Cobra 29 LTD CB Radio

1 Answer

When radio is keyed up the RX/TX ligh changes to red but not movement on the needle gauge and also i have no backround noise when squelch is turned off but other times the whole radio will work fine just...


Sounds like you have an intermittent antenna problem.
Open the case and check the wire that goes between the antenna connector and the circuit board. Check both ends of the wire and make sure both ends are securely soldered. If OK, make sure the coax cable is good. Inspect the antenna installation for problems.

Not really enough information given to precisely locate the problem.

....Don at NTCB, Inc.

Jun 28, 2011 | Cobra 29 LTD CB Radio

1 Answer

My rx/tx light is green untill i push on the mike. then the light turns red. and the antenna led theres nothing. whats could be the cause and the fix...and the swr metter goes into the red all the way to...


Its working alright then...what the antenna light is for in case the SWR is too high. If it does not come on---Then it means your antenna works good.

May 16, 2011 | Cobra 29 LTD CB Radio

1 Answer

I just picked up a 99 china cobra ltd st. Tx works on all channels, but no Rx on channels 1-19. Any help pointing me in the right direction would be greatly appreciated.


May be bad antenna match on that end. Check SWR at CH 1 and at CH 40. If quite different readings you will need to adjust the SWR and maybe the antenna itself.

Feb 18, 2011 | Cobra 29 LTD CB Radio

2 Answers

I hooked up my radio and when i push the mic the red antenna light came on so i grounded the radio better still did it changed the braket for the antenna still same thing changed antenna still samr thing...


It is important to tune your CB radio antenna to the proper length. The length must exactly match the wavelength of the frequency you transmit on. Or be really really close.

All Cb antenna's have a way to adjust the length of the antenna. If it's a mag mount, the metal whip can be slid in and out of a metal collar. Usually a set screw. If its a fiberglass whip, the way to tune it is on top. It either has a small metal rod with a set screw to adjust the length, or it threads in and out to adjust length.

Either type you have it will need to be adjusted for proper length. Here is how to tune the antenna to lowest SWR.

Some radios have a built in SWR meter. Some do not. If yours doesn't have an SWR meter, then you have to use an external SWR meter. Radio shack carries one, and you can find them cheap on ebay.

If you have a built in SWR meter or external, the procedure is the same:

1. Turn the radio to CH 20.(This is the center of the band.)
2. Switch the meter switch to CAL. (CAL stand for calibrate.
3. Key the radio. (Important. Do not talk while keying the radio.)
4. turn the CAL knob up until the meter hits the CAL mark.
5. Now while still keying the radio flip the meter switch to SWR.

Where the meter falls after that point is you SWR reading. If its above 3, that is real bad. 2 is not gonna kill your radio but its not the greatest. 1.5 and under is a good place to be, but the lower the better.

If your SWR is high, Here is how to find out if your antenna is too long or too short.

1. Turn to CH 1
2. Repeat SWR procedure. You must calibrate every time you do it.
3. Remember the SWR reading.
4. Turn to CH 40.
5. Again repeat SWR procedure.
6. Compare the reading between CH 1 and CH 40.

Now if the SWR is higher on channel 1 then channel 40 your antenna is too short. You must make it longer.

If the SWR is longer on channel 40 then on channel 1, then the antenna is too long, you need to make it shorter.

Make height adjustments about an eight inch at a time, and take reading each time.

once the SWR is significantly lower and the reading on channel 1 and 40 are about the same, you a about matched. At this point turn the radio to the center of the band, channel 20 and take an SWR reading.

You should now have a low SWR reading, 1.5 or under. If you are 1.5 or under, you are good to go.

If you cannot get the SWR to an appropriate level, there may be an antenna problem.

Nov 10, 2010 | Uniden GRANTLT 40-Channels Base CB Radio

1 Answer

Every time I press my MIC to speak into it the red lights on the RX/T and ANT light come on alerting me of a problem. How can I fix this.


RX/TX light should change to red, however the ANT light is a bad light. This means that your antenna is not adjusted properly. Do not key the radio or talk on it for any other reason then to check the SWR and tune the antenna. If you have the manual that came with your cobra 29, there is a section that explains how to check the SWR. And the manual for the antenna, it will explain how to adjust it.

If not, here is how to do it.........

How to check the SWR on a Cobra 29

Step 1. Find out what your current SWR is on the center of the band.

  1. Turn the radio to channel 20.
  2. Set the S/RF SWR CAL switch to CAL.
  3. Turn the CAL knob all the way counter clockwise.
  4. Key the radio. Do not talk into the mic.
  5. While holding the mic key, turn the CAL knob to the right until the needle reaches the CAL mark on the top right of the meter.
  6. Now flip the S/RF SWR CAL switch to SWR while still holding the key on the mic.
The needle should fall. Where ever the needle is while holding the key is your SWR reading on channel 20. It should be as low as possible. If its a reading of 2, then its not gonna kill the radio but is border line. Any higher and its bad. Using the radio like this will damage the final output transistor. If its less then 2 this is better. You want it to be less then 1.5 or better.

The ANT light may come on with an SWR of 2. running the radio with an SWR of 2 shouldn't hurt the radio, but I don't like to mess around. Get it as low as possible.

How to adjust the antenna for SWR

The length of your antenna will change your SWR. SWR is basically how much RF energy is not leaving the antenna and getting reflected back into the radio. That's why it hurts the radio when its high. An antenna has to be the right length, matching the length of the radio waves in order for it to radiate all of the RF energy out of the antenna.

Most antennas have a way of lengthening or shortening the antenna. If its a mag mount antenna with a metal whip, there is probably a set screw that when loosened, will allow you to raise or lower the whip. If its a fiberglass antenna, under the rubber cap at the top is how you raise or lower the antenna.

Figuring out if your antenna is too long, or too short

Here is how to know weather or not you have to lengthen or shorten your antenna.

  1. Take an SWR reading as explained in the first step on channel 1. Write down the SWR for reference.
  2. Take another SWR reading on channel 40. Again write it down for reference.
Now if the SWR is higher on channel 1 then on channel 40, its too short. You need to make it longer.

If the SWR is higher on channel 40 then channel 1, then the antenna is too long. You need to shorten it.


Make small adjust ments about an 1/8th to a 1/4th inch at a time. each time checking the difference between channel 1 and 40.

You will know when you are a good match when there is little to no difference between channel 1 and 40's SWR. Once you are satisfied that the difference between 1 and 40 is about the same, and much lower, then turn the radio back to channel 20 and take an SWR reading.

You will now find that the SWR on channel 20 is really low. Most likely under 1.5 or better, Almost nothing on the meter.


Here is a Meter Key, so you know what you are looking at.
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Oct 11, 2010 | Cobra 29 LTD CB Radio

1 Answer

Red RX/TX and red ANT light on my CB


Well,first hand ,some cobra radio,s have red some have green RX/TX lights, but are you modulating? Some green lights turn red. What is your standing Wave on the antenna,s? You need to check it and the output of the radio. To do this you need a watt or field strenth meter. Can get one at Radio Shack. Your standing Wave is ok as long as it is below a 2. That has to be done on the antenna. ..hope this helps...

Mar 11, 2010 | Cobra 29 LTD CB Radio

2 Answers

When i key up the mike the tx/rx light and the ant


your swr setting are off wack fix your swr

Oct 02, 2009 | Cobra 29 LTD CB Radio

1 Answer

Transmission only in close range when mic needle goes to far rt


Make sure your Antenna SWR reading is 1:2 or better, also have your antenna as hish as possible with a sufficient groundplane and remember that indoor antennas will not be anywhere as efficient as an outdoor one. If you have lots of surrounding buildings or trees this can effect your TX and RX.

Dec 27, 2008 | Cobra 29 LTD CB Radio

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