Top 10 Cobra 29 LTD CB Radio Questions & Answers

For normal operation, set this control to the center position.
This feature has several uses and can help receiver operation.
If a received signal is slightly off frequency, the Delta-Tune control can be used to òfine-tuneó your receiver. Fine tuning is accomplished by listening for a more readable signal at the speaker or by noting the Smeter reading when the Delta-Tune control is operated. Another use of this control is eliminating adjacent interference (bleed over from other channels). If an exceptionally high level signal from an adjacent channel is creating interference on the channel being used, the Delta-Tune can be used to minimize or eliminate the interference. Rotate the control until you obtain minimum adjacent channel interference. NOTE: Delta-Tune is operable only in the receive mode.

It doesn't actually help receive any better, just can help kinda like a clairifier.

Dean Pitts
Rollin CBs
Mt. Vernon, TX

Check to see if the meter needle is swinging backwards when you key up. If it does your final may be bad. If the needle goes forward and others say they see your keying up but no sound your audio chip may be bad; especially if you have tried so many mics and antennas. If your radio has a swr warning light and it comes on this could extremely limit your range and others may not hear you and contiued use will damage your radio. Good luck!!!

Here is a link to the Phantom CB's seb site, you can click on the brand of radio you want to peak, in you case, Cobra. Then follow through the chart to the Cobra 29 LTD Classic under the Cobra power mods, which tells you what to adjust and changes that can be made. Only one suggestion I have before you start, where it says to cut D11, don't, only turn up VR-4 for your modulation. That is the only thing I don't like with their instuctions is telling people to cut the modulation limiter. You can get full modulation by turning up the potentiometer, and if you cut the limiter, sometimes it will over modulate.

http://www.714xpress.net/714mods1.html


You need an inline power meter to peak the radio out. This is the quick and dirty way to peak and tune a radio. To properly align a radio, you really need an oscilloscope and other related test equipment.


If you have more questions, don't hesitate to post here or email me at [email protected]. I can't promise I will have an answer to all questions, but I will do the best I can to help.


Dean Pitts
Rollin CBs

YOU CAN ORDER THAT PART FROM COBRA ELECTRONICS ON THE INTERNET YOU HAVE TO REMOVE THE FACEPLATE AND UN HOOK THE DRIVET INSIDE THE RADIO IT LOOKS LIKE A SMALL RIBBON CABLE THAT GOES TO THE FACEPLATE. SOME TIMES THE DRIVER ITSELF IS THE PROBLEM. MANY SHOPS JUST DO NOT WANT TO FIX THEM BUT I DO.

If the radio is working don't worry about the meter unless you absolutely want it. These little meters are not very accurate or reliable. Get an external SWR meter to check the antenna.

When you say calibrate your radio, usually it means you are trying to re align the channels. However I do not believe that is the question you are trying to ask.

I think you are trying to ask is, "How to I tune my antenna?"

You cannot actually tune the radio. What you are probably talking about is your SWR. If so, Here is how to do it.

First make sure you are in an open parking lot. Structures like building, trees and other cars near by can give you a false reading.

Next with the radio on, turn to channel 20.

Make sure all the doors and windows are shut.

Flip the switch that is all the way to the left to CAL.

Key the mic and hold it. Then turn the knob all the way to the right marked SWR CAL up until the needle on the meter is all the way to the right at the little red triangle marked CAL. While still holding the mic key, flip the switch to SWR. The needle should swing back and will give you the SWR reading for that channel.

** try not to make any noise because if its picked up by the mic it will give you a false reading. Try turning the dynamic all the way down so it will not pick up sound."**

now if its 1.5 or lower your in good shape. You could always do better. If its 2 or higher your antenna is not matched. Here is how to tune it.

Use the same steps above to take a reading on channel 1 and 40.
You need to recalibrate each time you take a reading.

Now if the reading on channel 40 is higher then on 1 the antenna is too long. You need to make the antenna shorter. your antenna should have instructions on how to do this.

If it is higher on 1 then 40 its to short, it needs to be longer.

Follow the antenna instructions on how to adjust length.


Now if you really did mean, how do you align your radio, meaning tuning the channels, then you need an oscilloscope and a couple of other meters like a DMM and watt meter etc, and some specialized tools. Its also an involved process. I would suggest taking the radio to a radio shop. You can usually find them at truck stops.

i would highly suggest you take it to a cb shop to get a cb tuned and peaked. before you do that though, make sure you have a good antenna system. a good antenna will have a much greater effect on your cb than tuning and peaking. as far as output, who knows? it all depends on the skill of the person doing the tuning. be warned that any output over 4 watts is illegal and you could recieve hefty fines if caught with an illegal radio.

open the radio and turn vr 4 wide open but before you do get a new mic and hook it up to eliminate the squeal the turn up vr 4 to raise the modulation.

there are two lights for the antenna.when you are transmitting the top light will change from green to red the bottom shouldn't be on.this is the awi light. it means there is a problem with the antenna system, and you should get it checked. It could be the antenna swr ,bad coax,or the radio.Since you can't do anything with the coax or radio it has to be done with the antenna. Get a real SWR meter and check the SWR or have a tech do it. If the SWR is ok then your antenna just might be in the wrong spot ,or it may need to be grounded A tech will tell you the problem as soon as he puts his meter on it.

You have to press the transmit button to get the radio to send a signal that you can calibrate the SWR meter to. If you are pressing the transmit button and nothing is happening then it could be a blown final transistor, a bad switch, bad microphone connection etc.