Question about Cobra 29 LTD CB Radio
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
Posted by Anonymous on
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
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
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
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
SOURCE: CB transmission
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
Posted on May 14, 2008
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
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
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
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.
This is an easy adjustment. I fixed my false warning in a few seconds.
Posted on Jun 17, 2012
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