Question about Cobra 29 Lx Full-featured Cb Radio

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How to fix cobra 29 lx that will receive but not transmit?

Have tried new mic still will not transmit can not figure out issue have tried everything under the sun to get to transmit and still will not. PLEASE HELP!!!!

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  • Cobra Master
  • 1,795 Answers

Your final could be blown,thus no transmit . if you change it make sure you change the driver also and retune that portion of the radio.

Posted on Nov 25, 2014

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Posted on Jan 02, 2017

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SOURCE: Cobra 29 LTD Classic not transmitting or receiving

ant. light should only come on if you have a high vswr a bad thing did you check that cb/pa switch is set to cb check your swr this is not a good place to mount ant. as it is close to metal of back of cab

Posted on Dec 24, 2008

  • 200 Answers

SOURCE: cobra 29 nw ltd won't transmit

Have you cracked the radio open yet?  check for loose connections etc.  get back to me if that doesnt yeild any results

Posted on Jan 22, 2009

  • 89 Answers

SOURCE: Receives but does not transmit. It is a Cobra 29

There are a few different things that can cause this problem. 1: If it is a power microphone (a microphone that requires a battery). Try replacing the battery. 2: Broken wires that go from the microphone to the plug that plugs into the radio.You can try gently taking the plug apart and inspecting the wires. If only one has come loose, you can re solder it to the pin it came from. If more than one has come loose, find a wiring schematic for the radio that tells which wire goes to which pin and re solder appropriately. 3:Have the SWR's checked on the antenna. If the SWR's are to high and the radio has been being used in this fashion, it could have burned up the transmit finals in the radio. If this is the case, you will need to take it to a reputable radio repair facility to have fixed.

Posted on Nov 30, 2009

  • 773 Answers

SOURCE: 29 cobra ltd c.b. wont transmit or receive

make sure the RF gain is all the way up, and the dynamic is all the way up or most of the way up.

When you say the antenna is good, have you checked the SWR's and or have tuned the antenna to be the correct length for the radio? If this has not been done ever, your radio could be a brick.

Also, make sure the PA/CB switch is on CB. if its on PA(public address) it will not receive or transmit because it is on PA mode, which if you have one hooked up, a PA speaker, then you can talk to people through it out side your car.

Also, make sure the S/RF SWR CAL switch, its the first one on the left, is all the way up on S/RF. this is your signal/ receive setting for the meter. When you hold the key, does this needle swing forward? As well does the RX/TX light turn red? If it does, then the radio is transmitting.

There is another light on the radio under the TX/RX light. It is the Antenna warning light. If this light comes on when you transmit, or has come on all the time during transmit, and now it doesn't then the radio is a brick. That is a warning light. It means that the antenna is not matched, or has not been tuned to the radio. If this has not been done ever, you have killed the radio.

Here is why. When you transmit, you are sending off a radio wave. This radio wave, at 27mhz, is about 36 feet long. In order for the wave to radiate off the antenna, the length of the antenna has to match the length of the radio wave. Now it does not have to be a full 36 feet. It can be an exact multiple of 36 feet. In other words it can be 1/4( one quarter) or 5/8(five eights) of a wave in length. 1/4 of a wave is 108 inches, or 9 feet long. Your antenna is still probably does not seem 9 feet long, but there is usually a loading coil that is not exposed making up the rest of the length of antenna, so that it matches the length of the radio waves electrically. If you were to stretch the coil out with the antenna whip, it would be 9 feet long.

When the antenna does not match the wave length, part of the RF energy does not leave the antenna, and goes back down the feed line(coax) and hits the transmit transistor. Prolonged reflection to the transmit transistor, otherwise known as the final will blow it out. As well depending on how bad the length was off, the more off, the more reflect energy, the more RF energy you are blasting back into the radio, and this causes more things then just the transmit to blow out. Some time the receive goes along with it when it finally goes.

So if the RF gain is up all the way, which by the way is basically how much receive you have, and there really is no reason to have it down at all, and the CB/PA switch is on CB and the needle does not swing forward when its on the S/RF setting, chances are that the radio is now no good.

It is fixable, but if there are no CB shops near you then you will have to send it out. And Cobra will not cover this under warranty because its stated in their warranty that they do not cover damage due to high SWR.

Posted on Apr 06, 2010

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1 Answer

Cobra 29 ltd classic year 2004. rf gain problems.


Put SWR meter between your antenna and output, test wave length receive/transmit, might need a ground plane or center loaded stick.
Could be transceiver relay, try clicking mic fast, it should click out as fast as you key the mic.

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Since the radio cannot transmit on Weather bands, there is no need for the radio to detect if it is transmitting when receiving weather.
In CB mode (on CB channels) the radio will mute when transmitting. So... a guess is that it is muting, or transmitting all the time in CB mode. Check for a mic problem by removing the Mic from the radio ... if it receives CB with no mic connected, then there is an issue with the mic. Otherwise, unless the unit is in PA mode (public address mode) it is likely something internal and beyond the scope of this service.

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My Cobra 29 LX receives including the weather but can't transmit


If the relay contacts are closing. You may have blown the output transistor, however a broken wire in the microphone can also create the symptoms you describe. .

you can check by using a #47 light bulb soldered to a PL259 connector as a dummy load. If it lights, the carrier is present, but you may not have voice modulation which will show as differences in light intensity as you speak. If no modulation, the microphone is the first thing to look at.

The relay contacts may also be very pitted or corroded and not achieving continuity.

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Transmits but does not receive. cobra29LTD Can it be a active copponent


where is the RF gain? It should be all the way up.

The other thing that can cause no receive. Its a common issue. If you have a mic with a broken wire in cord, if its the wire for receive, then when the key is released the radio will not go into receive mode. The switch in the mic determines weather the radio is in transmit mode or receive mode.

So make sure the RF gain is on max, and try another mic.

Sep 26, 2010 | Cobra 29 LTD CB Radio

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I have a new cobra 148 with ssb, about 6 months old, while i was away there was a storm, now the radio doesnt work , recieve or transmit, i also have a cobra 29 ltd that wont transmit but it will recieve....


make sure the mic is good. If for some reason the mic went bad, it will not receive or transmit.

As for the one with no receive, it most likely needs a new final.

If lightning hit your antron, it would be in pieces.

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My Cobra 29 LTD sometimes does not work even though the lights remain on. In other words I can't talk on it or hear anyone even though it appears to be operational


Your mic or mic jack is faulty. Try a different mic. In cobra 29's and some other variants, when you disconnect the mic, the audio is disabled. It will still receive, and transmit(possibly) but you will hear nothing from the radio.

It could be,
  • Broken wire on the back of the mic jack in the radio.
  • Broken wire in the mic cord.
  • Disconnected wires in the mic for the switch.
  • Dirty mic connection pins.
Most likely the problem is with the mic, and not the radio.

Oct 21, 2009 | Cobra 29 LTD CB Radio

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When i click the mic i get no transmit


If the receive works ok,sounds like a mic
problem,try another mic if you can find a
buddy who has a Cobra that may let you
try it most all Cobra mic will work but not all.
Good Luck

Sep 08, 2009 | Cobra 29 LTD CB Radio

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I have a cobra 29 and all it will do is light up. It will not receive nor will it transmit. What might be the problem?


the easiest thing to check first is the mic..........if the mic is broken cobras wont receive or transmit
hope this helps.......good luck!

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