Question about Cobra 29 WX NW ST 40-Channels Base CB Radio

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No front panel lighting

The dimmer works properly in adjusting the lighting of the channel display and signal meter. But the front panel does not light up. Is this a simple fix such as a bulb replacement?

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Re: No front panel lighting

The "nightwatch" lighting uses an EL or electroluminescent material that does degrade with age. If the radio is old, then it may be lighting very dimly (check in a dark room with the dimmer at full bright). The material is connected by a ribbon to a special high voltage pulsed powersupply that runs at about 500 volt. If the power supply is working then a new face would be in order or a new radio. If the powersupply is not working it may be repairable but requires working with surface mount components. Either way, it is NOT a simple lightbulb fix. I have successfully repaired and do stock the smc components to repair but cannot get the faces through cobra ($$$). More info? Contact through

Posted on Feb 22, 2007

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How to adjust the antennae to get signal uniden 538w

doesn't matter what kind of radio the procedure is the same.First you need an SWR hook it up properly and take a reading on channel 40 ,write it down then channel 1 , write it channel 19 and write it down . If the number on 40 is higher than on 1 your antenna is long and it has to be adjusted take the allen wrench provided with the antenna and loosen the tip.Bring the tip down about 1/4 inch at a time checking both channel 40 and 1 as you do this . onnce you get a good match then you are ready to go.

Aug 29, 2014 | Uniden CB Radios

1 Answer

Cobra cb radio backlight inoperable

look inside at meter--two wire bulb with rubber boot slides at a angle into the meter and is easy to replace.

Apr 06, 2012 | Cobra 29 WX NW ST 40-Channels Base CB...

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The lights on the front of my nightwatch is not working but the rest is the meter and channels light up and the dimmer works just the backlighting wont whats the problem thanks

  • That Night Watch face plate is AC ran by a converter inside the radio. The LEDS are part of the face plate and sold as one unit. The face plate goes out often on these radios. In short the face plate needs replaced if you want it to light up. The radio's performance will not be effected by this. Cobra can actually switch that out fairly cheap. Cheaper than buying a face plate used on the net.
Regards, Tony

May 20, 2011 | Cobra 29 WX NW ST 40-Channels Base CB...

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I just need to know how to use it for conversations and what every turn dial means.

you need to hook this up to an antenna. If you are putting it in a car, you need a mobile antenna, if in a house, you need a base antenna. The antenna needs to be tuned for best SWR or you will damage the radio.

Starting from the left of the radio.

Knob 1. Volume/ squelch. The little knob does the volume of what you hear. Big knob squelches out static noise.
knob 2. Dynamike. This is the volume of your voice transmitted. Its how loud people hear you.
Knob 3. RF gain. This is the receive sensitivity. The higher you turn this, the further you can hear. There is almost no reason for you to have this anywhere but full.
knob 4. Delta Tune. This knob should be in the center. If you encounter some one transmitting off frequency, you can move your receive up and down frequency so you can tune that person in. It does not effect your transmit frequency.
Knob 5. CAL. This is to calibrate the meter for taking an SWR reading off the antenna.

Switches starting form the left.

Switch 1. Meter switch. S/RF - will show on the meter, Your signal going out when transmitting, and the signal coming in while receiving. SWR - will show on the meter, your SWR on that channel after you have calibrated the meter. CAL - This is used to calibrate the meter in conjunction with the CAL knob.

Switch 2. ANL - Automatic noise limiter. - This gets rid of electrical interference noise from the vehicle, or other interference sources. ANL/NB - This is the same as ANL, but with NB "noise blanker" This function blanks louder noises that may make it hard to hear people. It's kind of like an automatic squelch, but not nearly as effective as the actual squelch. Also, NB will lessen your receive in that, really low signals will be blanked out.

Switch 3. CB - the radio is in CB mode. This is the normal operation mode of the radio. You can transmit and receive as normal. PA "Public Address" - If you hook a PA speaker to the PA jack in the back, you can mount the speaker on the out side of the vehicle, and talk over it (Its loud). Also, anything you receive over the radio when not holding the mic key, will come over the PA speaker. This is useful when you are not in the vehicle, and need to hear when some one comes on the radio.

Switch 4. BRT and DIM - this is the brightness of the meter light and channel display. BRT stands for bright.

Switch 5. Normal and CH 9, When the switch is in the normal position, everything is normal, but when you flip it up to CH 9 it instantly puts you one channel 9 with out having to turn the dial. CH 9 is the international emergency channel. So it lets you go to Channel 9 quick. when you put it back to normal it will put you on the channel you were on.

Meter explanation. - You have 3 horizontal lines on the meter. the top line is your SWR (only when in SWR mode on the switch. The next one down is you Signal going out. And the bottom one is your signal coming in, in DB's. ***Also noted that part of the SWR line has a CAL )calibration mark. When you have the switch in CAL, and key the mic, you turn the CAL knob up until the needle is at CAL triangle, and then put the radio on SWR and key it. where the needle falls, on the top line is your SWR. If it is in the red your antenna is not tuned, and you can damage your radio.


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 12, 2010 | Cobra 29 LTD CB Radio

1 Answer

How to replace the front panel light

Meter light is an easy fix if you can get ahold if an led light.Now the channel is a different ball game.The radio will have to be taken aprt. The channel display is a 16 leg chip.You will have to go in and unsoilder the one thats in it sounds easy, it isn't then you will have to replace it and soilder all 16 legs without touching the one next to it, thats if you can get it out without messing up the board...A cb shop sure sounds good at this moment doesn't it.

Apr 12, 2010 | Cobra 29 LTD CB Radio

2 Answers

Dimmer lights arent working right and meter light is out

With the Cobra NW units, they have a separate power supply for the lighting, in most cases the power supply fails and the NW lights do not work any longer., there is also a socket where the tape lighting for the face plats back lighting slides in to the socket this may be loose as well. If you need further repair service let me know.

Feb 28, 2010 | Cobra 29 WX NW ST 40-Channels Base CB...

1 Answer

Antenna light comes on when trying to transmit

Its the antenna. it is not tuned correctly for the radio. First, stop transmitting. You can burn out the final transistor. If the antenna light is coming on, that means your SWR is too high,

first. Check to make sure that the antenna coax is securely attached and fastened tightly to both the radio and antenna.

Next inspect the coax. Make sure there is no damage to it. If there is a slice in it, it is kinked really bad, that could be the problem.

Now, if the coax looks good and is connected tightly, now its on to tuning the antenna. Your antenna is either too long or too short. Antenna's usually have a way to adjust this. Most common is where a metal whip sits in a collar. You loosen the collar, and you can move the whip up and down in it. That is how you adjust the length of your antenna. Fiberglas whips usually have an adjustment at the tip that you can adjust usually by screwing it in or out.

Now here is how to check your SWR.

Make sure you are in an open area like a parking lot as structures such as buildings and trees can cause reflection and give you a false reading. Always take an SWR reading with your doors and windows shut as not doing so can also cause a false reading.

Now that you are in an open area, turn on the radio and turn to channel 20. flip the switch located all the way to the left by the signal meter to CAL. Now turn the knob all the way to the right just before the channel selector marked SWR CAL all the way down to the left before you start. Now key the mic without talking into it and turn the SWR CAL knob up until the needle on the meter is all the way to the right to the mark for CAL. its a little upside down triangle with the letters CAL next to it. You want the needle to be on that triangle. Now while still holding the key in, flip the switch all the way to the left next to the signal meter up once to SWR.

The needle should swing back giving you your SWR reading. Ideally you want this reading to be as low as possible, but 1.5 and under is acceptable. If it is higher then 3 and in the RED stop transmitting. Try to do the steps quickly so you can un key as soon as possible to avoid damage to the final resistor if the SWR is higher then 3.

If the reading is 1.5 or under and the ant light is going on, it could be something else. I will go more into this at the end.

Now we have to figure out if the antenna is too long or too short. Here is how to do this.

Turn to channel 1 and repeat the steps to take an SWR reading. Make note of the reading.

Turn to channel 40 and repeat the steps again to take an SWR reading. Not that number.

If the SWR is higher on channel 40 then channel 1, then your antenna is too long and you need to adjust your antenna so it is lower.

If the SWR is higher on channel 1 then on channel 40, then the antenna is too short, and you need to adjust the antenna higher.

If the signal is over 3 on both channels, then there is something wrong with either your coax, antenna or both, and you should replace the coax, and if its still high, the antenna.

If your antenna is too long or too short, make adjustments to correct. Raise or lower the antenna a 1/4 inch at a time. each time taking a measurement to see if it is still to long or too short. You want to try to get the SWR the same on 1 as on 40. And channel 20 will have the lowest reading.

If your SWR reads low, under 1.5, or even a 2, the light should not come on. If you have had the radio worked on at a radio shop, or purchased it from some where that modifies the radio to put out more power before they sell it, then that can cause that light to go on falsely. Purchase an external SWR meter. You can get one off ebay, or from radioshack. Check the SWR with the meter, and if the SWR is still good, then you can do 1 of the following.

1. ignore the light because it is not right.

2. go in the radio and try to adjust VR6 so that the light doesn't go on. Not recommended if you don't know what you are doing.
3. take it to a cb shop and have them adjust VR6 for you.

I would leave it alone.

Most likely your antenna is not tuned properly.

Apr 26, 2009 | Cobra 29 LTD CB Radio

1 Answer

Lazy signal needle

Probably NOT the potentiometer that assists the meter. I would suspect a abad needle in the meter. I'd see if you can get to the adjuster screw on the meters front. Many times it's hard or impossible to adjust due to the way it's mounted.

Jan 12, 2009 | Midland 4001 40-Channels Base CB Radio

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