Question about Cobra 29 LTD CB Radio

4 Answers

I am having a problem with mt cb. I used all new coax, antenna, antenna stud and mount. New mic and radio. The problem is I hook up the swr meter, keyed and the meter swung hard right. I have changed

I am having a problem with mt cb. I used all new coax, antenna, antenna stud and mount. New mic and radio. The problem is I hook up the swr meter, keyed and the meter swung hard right. I have changed the antenna, and coax, and all mounts and antenna stud. Same thing. Put a dummy load in line to check the radio if it works. It works. Changed height of the antenna. still high swrs. Help me please

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You didn\'t mention what type of antenna you had but unless it is 4 foot long or longer it is going to have SWR. Also SWR meters are voltage reading devices that can be very inaccurate. Your radio has an SWR function that I would trust long before many of the "truck stop" SWR meters. You mentioned you were using a "Stud" mount. That leads me to think you are using a mirror type mount or L bracket where a PL-259 coax end will connect at the bottom and a 3/8 inch by 24 or 28 (can\'t remember) female is at the top to screw your antenna into. If so it is critical that the stud is not touching the bracket and shorting it out. There should be 2 plastic type washers that fit on the stud and insulate it from the mount. You said on the dummy load your SWR was good so we know the coax line is ok that far. If there is any problem then it has to be at the mount or something wrong with the antenna.

A poor ground at the antenna mount can cause an SWR meter to false read. Mirrors on doors are usually a poor ground. You can run your own ground wire to the mount from the body yourself.

If you have checked the mount and the antenna is good then you should be able to talk and receive on the radio. If you turn on the radio and hear people talking, that is a good sign. Try to make a contact but remember CB radio is only good at a short distance. The only other thing I can think of is the location where you mount your antenna. The antenna likes to out in the open and not crowded up next to a truck cab or tailgate. If it is mounted to close to another object that will carry current, that object will absorb a great part of your signal and cause significant SWR.

Remember: don\'t trust an inline SWR meter very far. Try the SWR meter on your radio. If shows OK, go ahead and use the radio and don\'t worry. Keep your antenna in the clear as much as you can and be sure the mount is grounded.

Another thing I do is run my power wires from the radio direct to the battery. The battery acts as a filter and reduces noise. Hope this helps

Posted on Aug 27, 2014

  • Jim Verge
    Jim Verge Aug 27, 2014

    Keep in mind that IF the stud mount has an SO 239 coax connector instead of a bolt, it will only have ONE nylon insulator that will go on the top of the bracket where the 3/8x24 nut that you screw the antenna into goes. That SO 239 MUST ground to the braket. If you are using the Stud mount that has a bolt instead of the SO 239 coax connector, The Braided side of the shield must be connected to the bracket as a ground and the Center conductor must be connected to the 3/8x24 bolt. The bolt will then go through a nylon washer (Smaller diameter part facing up), then through the bracket hole, then through the other nylon washer (Smaller diameter side facing down, a washer or two, and then screw into the 3/8x24 tall nut that the antenna screws into. I would sooner trust the external SWR meter than the ione in the radio. They have never proven to be accurate in the 30+ years of repairing CB\'s and Amateur Radios. Best of luck.

  • Jim Verge
    Jim Verge Aug 27, 2014

    What State do you live in? Are you in New England?

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Its so easy.Check again the soldering at Coaxial Connectors.Check continuity at Coaxial Cable.Check Connectors.
If it is OK, Bad assembly of Antenna.Check it again.
The SWR readins are showing you that you dont have 50 Ohms of Impedance.the cable or connectors are making short circuit.
If not write me again.

Posted on Aug 27, 2014

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Hi, You didn\'t indicate what kind of antenna you have or your experience level so this may be in your knowledge base. If it is a magnet mount, make sure it is not near any metal like a roof rack and try to get the magnet close to the center of the roof. If you are using a 3/8 x24 threaded mount like one used with a firestick, make sure it has the coax fitting grounded. That is, if the coax screws into the bottom of the 3/8X24 mount, be sure that there is not a nylon washer between that part and the bracket. You only want the nylon on the top of the bracket so that the hot side of the coax is not grounding out to the mount. If this is on a truck mirror bracket, be sure that the mirror bracket is grounded. Some tractors have fiberglass doors and the fiberglass does not allow the bracket to be grounded. If this is a bumper mount, be sure that the antenna is as far away from the body as possible. If the antenna is mounted on a pickup truck bed toolbox, it should be a metal toolbox. If the antenna bracket is mounted on plastic or wood, you have no ground. You need to have the antenna bracket going to ground with as short a path as possible. Otherwise your SWR will be sky high. These are very common SWR issues I see all of the time. If you are using an illegal power amplifier, there are other possible causes. I can\'t go into those here as that would take up more space and time than I have at this time. These are very basic ideas for you. As previously stated, I\'m not sure what your experience level is with mounting CB antennas. I really hope this helps. Best of luck. Mr. 44

Posted on Aug 27, 2014

  • Jim Verge
    Jim Verge Aug 27, 2014

    Are you calibrating the meter on the FWD setting and then flipping the meter to SWR function to read the SWR ?

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  • 21 Answers

Ok, you have a high SWR.. this is what you can do.. you're gonna need to check the Radio's coax connection to see if it's loose on the Radio itself.. you're gonna have to open the Radio cover on the speaker side.. now go look at the connections on the pc board itself and see if there is a possible broke connection.. one is pcb ground, and one for the center. also, you might want to get a phillips head screw driver and gently tighten all the screws on the pc board. becareful going in there.. after this said and done, check the antenna connector itself to see if it's loose. if so, then you're gonna have to a pair of pliers to turn the nut on the inside while you use wrench to hold it in place on the outside.. now you're ready to test the radio.. don't put the cover on just yet until you see the results. set up your SWR Meter to the Radio and then set up the dummy load and do a SWR Test. if the reading is good, then the Radio is all set.. now for the Antenna.. you said that it's all new, but regardless you need to test it too.. check both ends of the cable and do a condinuity test.. get a ohm meter that has an audio sound. this will help you.. set the meter to ohms/conditnuity.. then short out the probes to get a ZERO reading/audio sound.. now take one end of the of the cable and put the probes on the connector.. one probe for the outter ground shell and the other probe to the center pin connection. if you see a ZERO reading or an audio sound, that means you have a short in the cable.. another way is to do it end to end.. put one probe on one end of the cable, and the other probe on the other end.. test the ground side first.. if you get a sound or a ZERO reading, that means you may have a short in the cable itself and may requier to remove the connectors.. some cases you might have to replace them.. remember to calibrate your meter when testing let me know how it goes.. I'll continue to help you.. you can contact me on Facebook.. https://www.facebook.com/pages/ANR-Communications-Repair/136358796473669?ref=bookmarks Good Luck..

Posted on Aug 27, 2014

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Posted on Jan 02, 2017

Anonymous

  • 1139 Answers

SOURCE: CB transmission

Hello 64driver,

Make sure the radio is grounded properly and that the SWR is around 1.2:1, 1.3:1 is good but try to get it to 1.2:1. Also take a power output reading while keying the mic. To do this with your power meter put it in-line with the CB and your antenna and key the mic you should get about 4 to 5 watts PEP. If this is the case your unit is putting out the proper power level, if not have the power amplifier checked by a qualified repair shop.

I hope this helps

Shuttle83

Posted on May 14, 2008

JOHN BABA

  • 1274 Answers

SOURCE: cobra 18 wx st receives-wont transmit

Take the cover off, flip it over solder side up, check all solder joints for cracks, cold solder joints, check the safety diode where it comes in the radio, before I go further, can you pick up the weather channel?...Does the PA work?...need to check the pre-driver and finals,audio chip, hook up the power meter using a coax three foot jumper from the output from radio to the input of the watt meter, then the antenna, first check the SWR, on the scale on the meter to cal/swr mode,adjust it to spec, then while still keyed down turn the dial to SWR,if it is the safe range your ok,then turn the Dial to 10 or 20 watt scale and key the mic. Does it have any wattage? If not suspect the finals, they are located on the back rail, if it does have RF then its the audio chip, its located on the right side rail facing you,closest to you.remove it and replace it with same ....hope this helps....

Posted on May 21, 2010

steve132003

Steve Tompkins

  • 98 Answers

SOURCE: Cobra NW LTD CB radio

Get a good antenna from Radio Shack or www.copperelectronics.com. Test your SWR it should be 1.5 or less. That light in the radio just indicates a problem(but sometimes there is no problem--Someone has messed with the insides and adjust it wrong(misalignment). Ground to metal frame good. Change coax+ends. Sometimes end soldering is bad.

Posted on Nov 06, 2011

SD Tech

SD Tech

  • 14553 Answers

SOURCE: added new antenna and now im failing rf output and antenna radio test?18ft coax and a 48in ant.

First thing is to be sure the mount is not shorted in any way--and also to make sure that where it is mounted it is actually connected to ground--many newer vehicles have insulators so a bumper even if metal has no ground to work off of.

No ground, open or short in coax, open or short in mounting bracket all can cause no swr or high swr.

Posted on May 01, 2012

jonesboro

  • 1 Answer

SOURCE: 29 lx le new 200

The "Antenna Warning" came up on my radio too, a new Cobra 29LX, but I found another bunch of people having the same problem. This alert that you are seeing is only supposed to basically come up on that screen if there antenna is not connected. There is a simple adjustment inside the radio. The component is a little potentiometer that has to be turned with a little tiny screw driver. You can do this yourself, just look for the PDF file online that explains and shows you how to do it in a few seconds.

Here you can finds the link to the PDF file right here.
http://www.thetruckersreport.com/truckingindustryforum/cb-radio-forum/147114-i-need-some-help-antenna-warning-5.html

This is an easy adjustment. I fixed my false warning in a few seconds.

Posted on Jun 17, 2012

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1 Answer

I have tried 3 different antennas 2 magnetic and a k-40 solid mount now no matter what i do the swr is way to high and wont adjust and with 2 of them including the k-40 the antenna light comes on when i...


  • You need an external meter or at least replace the meter in your radio with another one. Even if it appears that meter is working right you need to put another one on there that will respond better. I repaired a Cobra 29 just two days ago with the same issue. The meter responded what looked to be great. Only the SWR was "8" so it said. I knew better. I had just tuned the radio and new better. I put in a new meter and the problem was resolved.
  • I always recommend an inline meter but the one on that CB should work good enough for a simple SWR check provided it is working right.
  • One more thing, not sure if the antennas you are using require you to provide a coax or weather the coax comes on the antenna already but I would suggest trying a new coax if your using the same coax for any of those antennas.
  • You may pop open the CB and make sure all legs of the P0239 antenna connector is solid.


  • Hope this helps and thank you for using FixYa.
  • If you have any questions feel free to ask.

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I have a magnum omegaforces45 radio. i am trying to set the swr and cant seem to get them out of the red. i am running wilson trucker 2000 with 10' shafts. single coax on clamp type mounts. all is clean...


Go to CH 20 and set radio SWR switch to CAL. (The RF only reduces receiver sensitivity to limit meter needle damage from very high power radios.) Key mic and use the SWR dial to move meter to the "set" mark on the meter. Now set the switch to SWR and key mic. The meter should be below 2 for a good match or below 3 for a fair match. If needle goes into the red or above 4 the antenna will have to be adjusted by using an allen wrench. If SWR it too high the antenna wire will have to be lowered. If it is already as low as possible you may have to trim a minute amount off the wire antenna at the bottom end. Do not trim at the top where there is often a small ball on the end. Before doing any cutting you should get another SWR meter to put in line between the radio and antenna to be sure where the problem is. Also double check all the connections. Make sure the inside wire of the coax is not shorted to the ground side. Sometimes people will forget the nylon insulators when assembling the antenna to the clamps. The lead center wire goes on the bottom bolt using a blue eye connector below the nylon insulators on both sides of the clamp plate. The shielding should be twisted and attached to the mounting plate using a yellow eye connector. Soldering the wire into the eye connectors is recommended. The center wire should not be touching any grounds.

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Sounds like a problem with your coax cable. You may not have the ends on the cable properly or the cable may have a kink or short in it somewhere. That is a sign of a very high SWR and usually means a short somewhere. If it is a mobile antenna make sure the little plastic washer on the antenna mount is installed properly. It is meant to insulate the antenna center conductor from the metal it is mounted to. It goes on top of the bracket and has a little raised collar on one side which should sit in the hole on the bracket.

Feb 03, 2010 | Cobra 29 LTD CB Radio

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here is some information that will help you test SWR with an inline watt meter. To get proper results you need to use an inline watt meter. Here is a really good site you can go to for help www.cbradiotalk.com

Equipment needed: SWR meter, short jumper coax 3 foot.
midland.jpgProcedure: The SWR meter needs to be placed in line between the antenna and the CB. Connect the antenna (normally connected to the back of the CB ) to the connector marked "Antenna" or "Ant" on your SWR Meter. Connect one end of the short jumper coax to the "transmit" or "Xmit" on the SWR meter. Connect the other end of your jumper coax to the CB.
Assuming you have a standard SWR meter the switches should read as follows: REF or SWR, FWD, and there should be a slide switch marked "set" or "Adjust". If different consult your meter's owners manual.
With the radio on the lowest channel (1 on CB) and the SWR meters switch in the Forward (FWD) position, depress the transmit switch (key up) located on the microphone. While holding the unit in this transmit mode, adjust the meter needle to the set position using the Set or Adjust knob on the meter. As soon as the needle is in alignment with the corresponding mark on the meter face, flip the switch to the Reference (REF) position. The meter is now showing your SWR on channel one. Note the value and quickly release the microphone switch. Record this reading.
Repeat the previous step on channels 19 and 40.
How to read your results: If SWR on channels 1, 19 & 40 is below 2.0, your radio can be operated safely.
If SWR on all channels is above 2.0 but not in the "red zone" (normally over 3.0), you may be experiencing coaxial cable reaction (bad quality, wrong length, etc.), insufficient ground plane, or have an ungrounded antenna mount.
If SWR is in the "red zone" on all channels, you probably have an electrical short in your coax connectors, or your mounting stud was installed incorrectly and is shorted. Do not operate your radio until the problem is found, serious damage can occur to your radio.
If SWR on the lowest channel is higher than it is on the highest channel, your antenna system appears to be electrically short. Your antenna length may need to be increased.
If the SWR on channel 40 is greater than that on channel 1, your antenna is considered to be "LONG" and reduction of physical height and/or conductor length will correct this situation.


Aug 01, 2008 | Cobra 29 WX NW ST 40-Channels Base CB...

1 Answer

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Hello 64driver,

Make sure the radio is grounded properly and that the SWR is around 1.2:1, 1.3:1 is good but try to get it to 1.2:1. Also take a power output reading while keying the mic. To do this with your power meter put it in-line with the CB and your antenna and key the mic you should get about 4 to 5 watts PEP. If this is the case your unit is putting out the proper power level, if not have the power amplifier checked by a qualified repair shop.

I hope this helps

Shuttle83

May 13, 2008 | Cobra 19 DX IV CB Radio

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You Need to check and set you SWR on the antenna system. You may also have a bad coax or the ant studs ( mounting hardward ) for the antennas may be bad. It definally sounds like an ant/coax problem Good Luck
Ed
NC Electronic
Mills, Wyoming

Dec 08, 2007 | Cobra 18 WX ST II 40-Channels Base CB...

3 Answers

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Checking and setting the swr can only be accomplished with an inline swr meter, not with the radios swr cal switch and the radios meter. Once you have set the swr of the antenna, you cal the radios meter to reflect the actual swr reading and use it like a dummy light on a car, just as an indicator of high swrs. To set your swr:

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.

Dean
Rollin CBs
Mt. Vernon, TX

Aug 23, 2007 | Cobra 29 LTD CB Radio

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Make sure you have a good ground for the radio and antenna. How long is the antenna coax if a little to long and you have extra what did you do with it coil it if so uncoil it and lay it out try it. If no luck I would shorten the coax and recheck your SWR.

Jun 22, 2007 | Midland 1001Z 40-Channels Base CB Radio

5 Answers

Matching Antenna, or ??????


If the antenna is tunable, you definitely need to start out by having the swr set properly on the antenna. Also, make sure the plastic ferrel, (the small round white piece) is between the top of the antenna bracked and the antenna itself. It is there to make sure the antenna does not ground out to the vehicle. If the antenna is grounding out, it will be like no antenna at all. I have also had a few customers that have had broken coaxes straight out of the factory package on cheaper antenna setups.

Dean
Rollin CBs

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