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SWR calibration waaay off the chart

I recently bought this CB, a big upgrade from my last POS. The factory installed antenna in my truck works fine, but when I recently upgraded my antenna to an oil coil, I can't get the SWR calibration to get below three or even meet the calibration mark on the meter. I've tried shortening the antenna, but the next step would be to start snipping pieces off. (I read that somewhere) Any before someone types it first - I'll say it.... Go back to the factory antenna! ;-)

Posted by MIke Payne on

  • Anonymous Jan 02, 2009

    I bought the same antenna for my geo tracker The swr on my 4 foot whip was a 1.2 all over the 11meter band i decided i wanted to try something a little nicer looking so i picked up a oil can type and installed it Did as the instructions said Put it all the way down as most cb antennas are to long. Then it said do an swr check and i did it was a 3 on 1 and a 3.5 on 40 so i cut a 1/4 off and nothing changed so i took another 1/4 off nothing i did this 8 times a total of 2inches and still no change so I went back to the trucker stop Bought a Little will Magmount thats all they had for under 50.00 as i juist spent 80 on the oil can. I took the magnet off undid the bolt Cut a slice in the side of the plastic ran a piece of flat bar and installed it. And again my swr was high i took 1/2 an inch of the whipp 2 times at 1/4 checking the swr each time, and i got a 1.1 on 1 and a 1.2 on 40 Im happy and it runs great... The reason i never put the whip back on I had allready gave it to another guy for his truck. anyways good luck and maybe go buy a wilson

  • jlaudio12 Jan 10, 2009

    I was the one who had the same problem with the oil can... I've ran into new problems with my tracker The little will worked for about a day, So i ran ground straps everywere i could still no Fix,. I was about to light the jeep on fire but the wife stoped me, So i cooled off and got the problem fixed been running for 2 weeks off and on road and The fix was a No ground plane mobile antenna, Works great on my hr2510 and i can tune from in the cab with the slider on the coax,, I payed 17.00 for a 4 footer off ebay and it works GREAT!!!!



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Powerfull antenas require longer coax!!!!ex:Willson 5000 ,18 feet coax!!!!

Posted on Dec 23, 2009



GROUND, GROUND, GROUND! If you are running more than barefoot, you should have everything GROUNDED. 95 percent of high SWR is related to a bad ground plane with the antenna. I would run ground straps from body to frame, doors, everything. If all else falls, run a ground strap, as short as possible, to the antenna mount. It'll work everytime.

Posted on Aug 11, 2007



Double check your connections and your cable for shorted PL 259 connectors. Oil filled antenna! Humm Sham on you if you are using a liner! Oh and quit sniping the antenna remember the higher in frequincy the shorter the antenna and longer for lower in frequincy. So it could be just where the antenna is located some antennas work good there but a diferent one wont try another spot also make sure your in a clear area when checking SWR not your drive way next to the garage or house or other car and finaly use an external SWR meter the ones on the radio some times SUCK.

Posted on Jul 07, 2007

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How do I calibrate my cb to match my antenna

1. You calibrate the antenna to match the CB rather than the other way around. Some antennas can be adjusted while others cannot. This should not cause a problem since the ones that cannot be adjusted generally don't need adjusting. The ones that can be allow for fine tuning to get a better match.

2.To match your antenna to your CB you set the SWR (Standing Wave Ratio) to it's lowest possible setting. SWR is the ratio of power that gets out through your antenna versus the reflected power that gets sent back to the CB. You want to get the most power to go out, or forward, through the antenna as this drives the signal that others receive. To set your SWR;

3.Connect an SWR meter between the antenna and the CB using a short piece of Co-ax cable. Set the switch on the meter to Forward Power. Key the CB and adjust the dial on the SWR meter until the needle of the meter is fully forward. Release the transmit button and change the switch on the swr meter to Reflected Power. Key the mic again and note how high the needle goes. If the needle doesn't go into the red it's safe to use but the lower the reading the better.

4. To bring it down check your antenna. Some antennas have a telescopic tip that can be extended or reduced by loosening a nut near the top. Try extending it fully and repeat the procedure at paragraph 3 above. If your SWR rises then try reducing the antenna length and check again. It's a matter of finding where you get the lowest swr by making smaller adjustments from the best of the 3 settings above.

5. You'll probably find that when you get a low SWR on one channel it will be higher on other channels. This is because of the frequency difference. Unless you use one channel nearly all the time, it's best to set the swr on the middle channel so if you have a 40 channel CB set the SWR on channel 20. The further you change up or down the higher the SWR will increase but it should be still within the safe range. If you set the SWR on say channel 1 the SWR will be twice as high when you change to channel 40 than it would have been if you set it on channel 20.

6. Most people never check their SWR so if you're using a commercial CB antenna, rather than a home made one, it should be factory set to give a reasonable match so if yours cannot be adjusted it's probably matching ok. A more common problem to look out for is the connection from the antenna to the CB. Make sure that the screening wire and the centre core are not touching. Even a single strand of the screening touching the centre wire will cause screeching on your transmission and before long will cause your CB to stop working. 73s and enjoy your CB.

Worked just fine in My big truck, but I upgraded to a BIGGER Radio and have installed my Cobra 29 LTD in my wifes truck. Used a mount and screwed it to the bed of the truck. Has 18' Coax, new mic., 3 ft...

is she getting bad motor noise? Make sure the ANL is on. Is the antenna tuned for best SWR? if the antenna is not tuned it can effect the receive.

I have a cb radio in the car and one at home if i got out in car i get about a mile and then no one at home can hear me but they can hear others can you help

radios are very picky beasts, the first thing you should do to get more range out of them is have them tuned by a cb dealer, from factory they rarely get out very far. also for the one that goes in your car antenna placement is very critical since your car body affects how the signal travels. even the length of antenna cable has a effect. when you have them "tuned" many times they will clip a resistor or "limiter" inside the unit. if you look up cb modding, youll find pages with 100s of makes of cb's and learn what modding them means. also look into high gain antenna for your units, if you want really long range buy a linear antenna "illegal in a lot of places" but you will be heard! people have used high gain antenna, and "skip" to talk to people in other states and countrys. skip is when the radio signal "skips" across the uppter atmosphere and uses it like a really big antenna. a lot of truck stops will have a good selection of antennas because cb is still very popular amongst truck drivers. i hope this helps you out and leads you in the right direction. cb is almost a lost art now and its nice to see people that are interested in it. take care and good luck!!

My antenna light stays on even after I have realeased the mike

Try checking the SWR's on channel 1, 20, and 40. The SWR's will change from the low channels to the mid channels to the high channels. The key is to make sure that the SWR's are around 1 or less at all three points. If the light goes out when checking one of them, then the problem is most likely the SWR's. If the light stays on when checking these channels, the issue might still be the SWR's but I would look at the grounding on the antennas. When holding the talk button on the mic and switching from calibrate to swr, can give a false reading. This is due to the calibrate circuit remaining open until you release the talk button. Take the SWR reading by releasing the Talk button on the mic after calibrating then pressing the talk button again after switching back to SWR. This will be the most accurate reading. From everything you described, I would be looking for a grounding problem with the antennas or coax, possibly even a rub though on the coax somewhere in the dash.

Cobra 29 ltd classic ant light

Your SWR is probably NOT fine. You need to use an external meter if you have had work done to the radio. Especially if you have had a swing mod done to the radio. When you do this, the dead key of the radio is lower then the calibration knob on the radio can adjust for. It will always come up lower then it actually is.

Your radio might have been fine before the work was done on it because it was putting out very little power. Now you are most likely putting out 50 watts or more. Big jump from 4 watts.

When your raise the power in a radio, you will notice more when the antenna is not properly tuned.

In most cases with a stock CB, even when the antenna is not even near tuned, you will get a reading less then 1.5 anyway.

the more power you put out, the more important it is to have a good match.

But an external SWR meter, and check it. be careful if the ANT light is on.

You might also want to check your coax, connections to it, and your antenna for anything wrong.

Cobra 29 ltd classic antenna calibration ??

You should not calibrate the antenna before you install it on the car!! the antenna needs to be calibrated on the vehicle that it is going to be on. Type of vehicle, different mounts, and many other variables can change the amount of reflection you will get.

j0hn9999 did a much better job but left some info out.

Take your SWR readings on channel 1, then on channel 40.... NOW, if your SWR is higher on ch 40 then ch 1, then your antenna is too long and it needs to be shortened. Refer to the antenna instructions on how to shorten the antenna.

If your SWR is higher on ch 1 then on ch 40 then your antenna is too short. You must lengthen the antenna. Again refer to your antenna instructions on how to lengthen your antenna.

You must calibrate each time you take a reading.

Make sure your doors and windows are shut when taking a reading

Make sure you are in an open lot when taking a reading as buildings, trees and other structures can cause reflection and give you an inaccurate reading.

If you adjust the length of your antenna on another vehicle and then put it on yours, the SWR will be off. It will need to be tuned again.

An external meter is better then the one in the radio, but will need to be hooked up in the vehicle you have the antenna on.

If you are not running any kind of power, or do not have a swing kit installed, and the radio is stock, the meter in the radio is more then enough to get a correct SWR reading.


You need expensive radio test gear to attempt what you want to do. You can not do this with an SWR meter

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.

Red ant light

The red light always comes on while mic is keyed. It is designed to do that. It will blink on and off while mic is keyed if there is a SWR problem. This is explaned in operaters manual.

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.

Rollin CBs
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