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

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Having trouble setting swr .moved anttena up and down 1/4 inch at a time and there is no change

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There are several things that can cause you not to be able to get an acceptable SWR.

The first is the most obvious. Poor antenna, or bad coax. Make sure your coax is good. Make sure the antenna is mounted in a good location.

Some things I have seen that cause this problem.

  • Wilson Little wil, almost impossible to get under a 1.6 SWR.
  • Fiberglass antenna's, a break in the wire near the top of the antenna. Will show the antenna as being too short, and adjusting the top will do nothing. This antenna is no good.
  • Common mode current. This is when the RF is traveling back down the outside of the coax, and or causes the coax to act like part of the antenna. SOLUTION. As close to the antenna as you can, take 6 to 8 inches of coax, and coil it into a tight coil, about the diameter of a spray paint can. In fact using a spray can to wrap the coax around works well. Use electrical tape to secure the coil so that it will stay tight and uniform. This will stop common mode.
  • missing foil/vinyl membrane on bottom of magmount antenna. This is essential for the antenna to see ground plane.
  • bad connections on coax connector.
  • Cracked isolator on stud mount.
  • incorrect procedure for taking SWR reading.
  • Poor location of antenna. E.g. antenna's load not above roof of vehicle.
  • Incorrect length whip being used.
  • corrosion of any part of the antenna system.
There are some cheap antenna's out there that you just can't get lower then say a 1.5 or worse, like the wilson little wil. Wilson makes great antenna's. The 500, 1000 and 5000, as well as their silver load antenna's are excellent. I have been able to get them all to at least a 1.1 SWR, and some like the 5000, and silver load fiberglass whip to 1.0 using an analyzer. The Little will is just a poor antenna. Anything under 2.0 SWR is okay of a barefoot radio, although I don't like going over 1.5 my self. A barefoot radio, will do a 2 swr all day. If the radio is stock, and not peaked and tuned, 2 swr is fine and won't hurt the radio.

You should always try to get the lowest SWR that you can in any case. The lower the SWR, the more RF energy is leaving the antenna. As well, receive will improve the closer you get to a perfect match. This is known as being "On Que".

Check everything I have listed that applies. And if nothing fixes it, you may want to try a different antenna. Some antenna's just don't work well on certain vehicles.

Posted on Oct 13, 2010

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Genie Powermax 1200 installed but only move approx 6 inches at a time.


You need to program the unit for up and down stops you can download the instructions from the link below

http://www.geniecompany.com/data/products/genie_programming-excerpt_eng.pdf

Jan 02, 2013 | Home Security

1 Answer

Have a new cobra 29lx. Everthing works fine except for the SWR meter. Can't use the meter to adjust SWR. No matter what I do the meter stays the same. Sent to factory but they said nothing was wro


The SWR cannot be changed by rotating this knob. The SWR function allows you to determine the SWR or "match" of the antenna system and transmitter on a specific channel. The entire process must be performed whenever you want to know what the SWR is on a different channel. The SWR/CAL button toggles the meter between the CALIBRATE and SWR modes.
Set the radio to CH1. Press the SWR/CAL button. The radio CAL(ibrate) mode is now selected. Press and hold the mic PTT (or push to talk) button. Rotate the SWR knob as needed to adjust the meter indicator until it is on the SET mark on the dial. The meter is now calibrated for this channel.

While still holding down the mic PTT, press and release the S/RF SWR CAL button to the SWR setting to read the SWR on the meter.



This entire process should be done for Ch 20 and Ch 40. You must go through the CAL procedure for EACH channel before attempting to read the SWR.


Changing the SWR requires that the antenna be lengthened or shortened until such time that the SWR can be reduced no further. Typical SWR across the band may be:


CH1 - 1.5:1, CH20 - 1.1:1, CH40 1.5:1


or


CH1 - 2.2:1, CH20 - 1.7:1, CH40 2.3:1


The "dip" in SWR on CH20 is typical, as the antenna is the perfect length on only one channel - it will be come slightly too long or slightly too short as you tune up or down from CH20. The further away from CH20 you go, the poorer the SWR will be. You can "slide" the dip to any channel you prefer - say CH8. If you tune for lowest SWR on CH8, You might see CH1 with a 1.2:1 SWR, CH8 at 1.1:1 SWR and CH40 at 2.5:1. All are acceptable - sort of. Many manufacturers say up to 2.5:1 or even 3.0:1 matches are ok, There's no reason a quality antenna can't be tuned for optimum SWR in the middle of the band (CH20) to have less than a 2.0:1 SWR on CH1 or CH40, unless there is a ground issues or bad cable / antenna / connection somewhere.


You can view the manual here. I hope this helps & good luck!

Nov 30, 2012 | Cobra 29 Lx Full-featured Cb Radio

1 Answer

The light for high swr keeps coming on. replaced antenna and coaxle. how do i go about lowering the swr. is there a nob or switch for this. thank you


You cannot lower the SWR via the radio. it has to do with the antenna. The length of the antenna is essential to transmitting properly. It must match the transmitting frequency.

To check SWR tune to ch 20. Flip the meter switch to CAL. Key the radio without talking into the radio. Turn the CAL knob up until the meter needle is at the CAL mark. Unkey the mic. Flip the meter switch to SWR. key the radio again, and the meter will show your SWR. We already know it is high because you are getting antenna warning, but we will have a base line now to work on.

What you did was calibrate the meter for that channel. that is necessary to check the SWR. So you must calibrate for each channel you check.

You should at least be under 2 swr. Ideal is 1.5 or under. the lower the better.

If your SWR is high, your antenna is either too long or too short. To find out here is what you do:

Check the SWR on ch 1 and ch 40 calibrating for each channel. Compare the difference of the SWR between 1 and 40. If the SWR is higher on 40 then 1, your antenna is too long. If your SWR is higher on 1 then 40 your antenna is too short. All CB antennas have a way to adjust the length.

If its a mag mount, its usually a set screw you loosen to raise or lower the whip. Fiberglass antenna's usually have something under the cap at the tip to adjust. It will either be like the mag mount, with a set screw and a small rod to raise or lower it, or a screw, that you screw in or out to make it longer or shorter.

make small adjustments. 1/8th or a 1/4 of an inch at a time. Each time you make a change, take an SWR reading on 1 and 40 again and compare the difference. The difference should be getting less. Do this until there is very little or no difference between 1 and 40.

Then you go back to 20, because it is the center channel and check the SWR there. It should now be low. If you did a good job it will be under 1.5 and you are good to go.

Aug 07, 2011 | Galaxy Radios DX-93T Base CB Radio

1 Answer

I just got a cobra 29ltd army edition and i cant get the SWR right


Takes some time to get it down if you are new to it. Here is a step by step instruction on setting it.....



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

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

I've got a Cobra 29 with WX and BT, the antenna light comes on, the swr meter barely moves and it doesn't seem to send or receive, still gets weather. May have been run with a bad antenna, got a new...


Please make sure you are tuning the antenna correctly.



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.






Now: If you have adjusted the antenna properly and you still get the antenna warning light, then the antenna warning circuit may be out of whack. Use an external SWR meter.

You may also be getting common mode current. Its when RF comes down the outside of the coax. If the swr goes up with modulation then it's common mode.

Here is how to stop common mode.

As close to the antenna as you can while still inside the vehicle, take about 6 to 8 inches of the coax, and coil it up into tight even coils and secure into shape with electrical tape.

This is an RF choke, and will stop the common mode current.

If all other radio's are fine and no ant light come one, and are all showing low swr, then turn VR6 back to disable the ant warning light. "only do this if the ant light comes on when SWR is lower then 1.5 and does not swing up with modulation showing that the ant warning light is miss aligned.

Nov 07, 2010 | Cobra 29 LTD 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.
2d03348.jpg

Oct 11, 2010 | Cobra 29 LTD CB Radio

2 Answers

Swr to hi and can t get it down


I hope this will help you on setting your swr put the radio on channel 1 check your swr.
now go to channel 40 check the swr. If the swr is lower on 1 than it is on 40 the antenna must be shortened buy 1/4 inch.until you reach your desired swr.if the swr is lower on 40 than it is on 1 the antenna must be lenthened by 1/4 inch until desired swr.

Mar 28, 2009 | Cobra 29 LTD CB Radio

2 Answers

Cobra 29 ltd classic antenna calibration ??


Wow. That's not at all a solution to what this guy is asking. And why all the caps??

The one point jm77437 has that is correct is that you do not set the radio, you set the antenna. The rest is blah blah.

Here is how you tune your antenna for you radio. First off it depends on what kind of antenna you have. most fiberglass antennas have a tunable tip to adjust the height of the antenna. Metal whips either have a collar at the base that the whip will either slide up or down in to adjust the height. The other type of metal whip's you have to physically clip to shorten the antenna, you must be careful with this type because once its clipped, that's it. You cannot add what you cut off.

I am going to give this example using a metal whip with an adjustable collar.

First after your radio is hooked up in the vehicle, drive to an open lot. Buildings and other structures can cause extra reflection. turn to channel 1. Flip the meter to CAL. Key the mic without talking. Now turn the CAL knob up until the needle reaches the little upside down triangle all the way to the right marked CAL. Now you have just celebrated your radio for your setup to measure you SWR. Now while still holding the key, flip the meter switch to SWR. The needle will move, and where it stops is your SWR reading. The lower the better. Anything under 1.5 is considered really good. But still, the lower the better.

Make note of what your SWR was on ch 1.

Now flip to channel 40. Repeat the SWR process. You must recalabrate each time you take a reading.

Now like jm77437 said. If your SWR reading is higher on 40 then 1, then your antenna is too long, and you must make it shorter. Loosen the collar and lower the antenna in the collar 1/4 inch at a time. check the swr each time you adjust the antenna.

If your SWR reading is higher on channel 1, then your antenna is too short. You must make your antenna longer. Do this by loossening the collar and pulling the antenna upward in the collar 1/4 inch at a time, again checking the swr each time you adjust the antenna.

What you want to achieve is having the same SWR reading on channel 1 and 40. then you have the best match you are going to get with that antenna.

If your swr is under 1.5 on all channels, you don't need to fuss unless you are a perfectionist. then by all means go ahead.

If your reading is higher then 3, or your ant light comes on, something is really wrong. Make sure your antenna is connected all the way, and the coax is not damaged.

Its important to have an appropriate SWR because if you do not, you are reflecting too much signal back into the radio, and eventually you will burn out your final transistor, and your radio will be toast.

Some tips: make sure you check the swr with the doors and windows shut. Make sure you are in an open lot. Remember to calabrate ecah time you take a reading. If you have had your radio peaked by a radio shop, and they have lowered your dead key, or have done a swing modification, then the meter in your radio will not work when taking an SWR reading and you will have to use an external meter.

Mar 12, 2009 | Cobra Radio Communications

2 Answers

SWR calibration waaay off the chart


You are using an inline swr meter to set your swr right, not looking at the meter on the radio? Here is the process to set swr on an antenna:

You must have an inline swr meter, which can be purchased online or from a truck stop. The ones at truck stops are cheap ones, but will do the trick for the most part.

You connect your antenna 18ft coax to the antenna plug of the swr meter, and a jumper coax (any length) to the transmitter plug of the swr meter and then to the radio.

Close all doors and make sure no one is messing around with the vehicle or antenna. You must be set up as you would normally be transmitting.

Now set your cb radio to channel 40 and your swr meter to fwd. Key up your microphone1.gif and at the same time turn the set knob on the swr meter until the needle is at the line that reads set. Unkey your mic and set the the swr meter to ref. Key up again and note what your reading is. Now leave the swr meter in ref and turn the cb to channel 1. Key up and take your reading. If the reading on ch 1 is higher than ch 40 you must raise the stinger on your antenna. If ch 1 is lower than 40, you lower your stinger. You are trying to get lower than a reading of 3 and as close to 1.5 as possible. If you lower your stinger as far into the antenna as it will go and you need it shorter, you cut the bottom of your stinger no more than 1/2" at a time, and recheck your swr reading after each cut.

Once you have gotten the best reading you can, connect your antenna directly back to the radio.

The setting of your swrs is to make your antenna as efficient as possible, by trying to get it as close as you can to a 50ohm impedance. THE ONLY PART OF YOUR SYSTEM THAT CAN CHANGE YOUR SWR IS YOUR ANTENNA, not your coax and not your radio. Your radio and coax can give you false readings, but only the antenna can actually change the swr.

On the swr meter, the fwd/ref switch stands for forward (power that is being transmitted out) and reflected (power that is reflected back into the radio.

Just for information sake, the swr cal switch on your radio is used to set the meter to reflect the swr that your antenna is set at. The meter on your radio is like a dummy light on your car. ONCE AGAIN, YOU CAN NOT SET YOUR SWR ON YOUR RADIO, only the antenna.

Dec 29, 2007 | Connex 3300 240-Channels Base CB Radio

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