Question about Uniden PRO510XL 40-Channels Base CB Radio

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My cb on uk40 has a problem, i get a strong signal on chnl 1 but a weak on chnl 40 it is a homebase airiel do i need to lengthen or shorten the airiel or is it cause i need to earth the airiel and is ther a special way to earth a airiel

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To ground the antenna you want to put a ground rod in the ground and use a copper braid strap between the antenna and the ground rod. Make sure no gas pipes or lines are in the area you are driving that ground rod into the ground. Put a couple round circles in the coax in a couple places too and make sure they stay. This will stop lightning from traveling into your home should there be a strike. You need to match that antenna to your radio. You want to hook an SWR/watt meter in line with your radio to get the best consistent reading. If you get a stronger signal with your CB on lower channels then I'm led to belive your antenna is to long. You really should put an SWR/watt meter in line to be sure of the SWR. If the SWR on channel 40 is higher than that on channel 1, your antenna is too long. If the SWR on channel 1 is higher than that on channel 40, your antenna is too short. Adjust the tuning coils according to your findings.

Posted on Mar 20, 2011

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  • 4 more comments 
  • Iron
    Iron Mar 22, 2011

    Glad I could help. If you have any more questions, feel free to ask.

  • uniace300 Mar 29, 2011

    just moved my homebase airiel out of the loft cavity on to side of house on a steel pole but now ive tryed it when i key the mike i get very little signal movement have i extended the airiel by adding the steel pole

  • Iron
    Iron Mar 30, 2011

    How many green bars light up when you key down on the mic? Do you have a meter inline to check your SWR? What antenna are you using? So we can figure out if you need to address the tuning coils of tune it another way. Putting your antenna in the air will get you a better signal because AM travels line of sight. Unless it has db gain to it the antenna does not add power to the signal. Make sure if you are using a metal antenna that no metal is touching the pole from the antenna. Have you obtained a signal report at all? If so what was it? If you had such a varying signal from one side of the band to the other and have not put an SWR meter in line to match the antenna to the radio it is possible your radio has suffered heat damage. One indicator would be 1 light or none on the meter on your CB.


  • uniace300 Apr 02, 2011

    hi the uniace300 has a built in anologe needle and when i hadent insulated the pole was only going up to one but now ive redone it and insulated with insulation tape and shotened the pole a inch or 2 and added a earth cable iam all good adding a zetagi b300p amp now i live at a vally mouth near some foothills any tips for me iam using a thunderpole i think top is up about 40'

  • uniace300 Apr 02, 2011

    soz just checked ebay its a VENOM Homebase high gain CB radio antenna aerial new 1/2 wave

  • Iron
    Iron Apr 02, 2011

    In the United States, FCC rules govern the height of CB antennas. The antenna is legal if it complies with either of the following rules:

    1. It is no more than 60 feet above the ground, OR
    2. It is no more than 20 feet above the top of the tree or building to which it is mounted.

    So get the antenna as high up as you legally can. A bad antenna up high will in fact outperform a good antenna down low. If you can run your coax cable for a distance and get your antenna on a hill or get the base of the antenna at a higher level you will be doing your CB a great service. If you do this then I recommended running the coax through PVC pipe to help keep the critters from nibbling your coax. Where the coax goes into your antenna you want to take your coax and run 5 circles about 5 inches or so in diameter and tape it so it remains that way. Lightning will not travel in a circle. This will help stop lighting from travelling to your CB and possibly you. I recommend RG213U coax or RG8. Some people will attempt to argue the 3' "rule" to the length of your coax. Just make it the length you need.Insulate all connectors with electrical grease and electrical tape. Make sure to mast that antenna. If you strap it to a tree I use movers straps that ratchet to ensure a non loosening grip. Glad you got your set up going. If you have any other questions. Feel free to ask.




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2 Answers

Both readings on 40 &1 are at 3 how do I get it under 2

Are you referring to swr? If so, look at the length of the antenna. If using a dipole, 468/MHz. Try that at those two frequencies and then see how far off it is from that number. Height above ground is also important but should not cause much trouble.

Jun 21, 2016 | Radio Communications

1 Answer

How do you used swr meter

The SWR meter on the radio is some what accurate, you might want to use an external meter. First thing you do is get a pencil and paper to write down the readings. On your meter you will notice it says FWD and REF. Set your radio on channel one then set your meter on FWD , key your mic , adjust the meter to the check line , then switch it to REF and do the same . Now write this number down. Switch to channel 40 and do the same then do the same on 19.If you have a final reading of 1.5 over the band then you are ok but if its higher on 40 then on 1 you have to shorten the antenna , if its higher on 1 then you have to lengthen it . Continue this until you have a satisfactory reading.

Feb 17, 2013 | Cobra 19 DX IV CB Radio

1 Answer

My swr are high with proper calibration

You may need to retune the antenna system if the coax has not been kinked or damaged. If you simply moved it over from the old rig, the antenna was tuned to that layout and the groundplane was the shell of the truck and chassis. The Cobra can tune it somewhat, but the best results are achieved with a baseline adjustment of the antenna. But check the coax for damage first, then check the connections to the antennas. If you are using a baseloaded whip, there is actually an inductor wound that attaches to chassis/coax ground, and it may be corroded. As may the center conductor terminal at the antenna.

If those sheck out okay Check to see if your SWR is higher on 40 than on 1, or if it is higher on 1 than on 40.

if it is higher on 40 than on one, shorten the antenna slightly, first and see how it looks.

If it is higher on 1 than on 40 try lengthen it slightly and see how it looks.

If you are running with dual whips, that complicates matters a little bit due to phasing.

I had set up a radio to be portable from vehicle to vehicle and found changing tuning length was always required when I moved it to a new vehicle. What made matters worse was I chose a cheap Walmart baseload and it had lousy quality coax.

Feb 20, 2012 | Cobra 29 LTD CB Radio

1 Answer

I have a cobra 29 wx nw st withwilson little wil entenna. I am having issues with a no swr reading on channel one even if I turn my swr cal all the way up. My 40 cal reads on the swr at .5 no matter how...

first of all you are going about it wrong. To set your SWR you check it on channels 1 , 19 , and 40. If you reading is higher on 1 than on 40 you have to shorten your antenna . if its higher on 40 than on 1 then you have to lengthen it. before you do any adjustments to it ,loosen the set screws and let the antenna fall to the bottom then bring it up 1/4 " and tighten the screws. You should also use an external SWR meter not the one on the radio. Thats good for making checks every once and a while. With the meter you key the mic and have the needle go to set then put it on for and key the mic to obtain you reading . Anything under a two is good .

Dec 16, 2010 | Cobra 29 WX NW ST 40-Channels Base CB...

1 Answer

I can hear people fine,but my volume to them is very low. i have checked the swr. when i key up the needle goes to 3

On some radio's that are bone stock with a stock mic you have to speak directly into the mic and not mumble;as for your swr if it's high on channel 1 and low on channel 40 you need to shorten your antenna if it's low on 1 and high on 40 you need to lengthen your antenna.Good Luck. Dan

Nov 30, 2009 | Radio Communications

2 Answers

I installed a browning br-51 cb antenna on my cb radio.

You need to shorten the antenna,adjust the whip all the way down and see what you have and then cut off 1/4" at a time remember this low on 1 high on 40 it needs to be lengthened high on 1 low on 40 it needs to be shortened . I hope this helps and good luck.

Apr 11, 2009 | Cobra Radio Communications

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 29ltd cb radio


A couple of suggestions:
1. verify that the RF Gain is maximum clockwise;
2. verify that the ANL or noise limiter is OFF;
3. pls add a ground strap from the body of the Cobra 29LTD to the chassis/GND of the vehicle or to your house GND connection;
4. Verify that your Wilson 5000 has a sufficient ground plane such as roof or metal objects.

Hope this be of initial help/idea. Pls post back how things turned up or should you need additional information.

Good luck and kind regards.

Thank you for using FixYa.

Jun 15, 2008 | Radio Communications

1 Answer

Cb radio

Most of the time this indicates a bad swr. You may have a poor ground or a bad cable. See more about swr here:

You may need to lengthen or shorten the antenna but you should have a swr meter to do this in the frequency you are testing. At radio shack they should have one for cb.

Hope this helped

You should refrain from transmitting until you get the swr down to about 1.2:1 or close.


Apr 06, 2008 | Cobra 29 LTD CB Radio

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