Can not fine tune SWR

Discussion in 'CB Radio Forum' started by PSM379, May 28, 2022.

  1. PSM379

    PSM379 Medium Load Member

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    Please excuse me if I come off as a rookie CB man. I’m no pro, they have interested me for a while and I know a few things though. After many issues and running with a few friends the other week that couldn’t even hear me from 100 yds, I finally swapped the old cobra that was in this truck when I bought it for my Galaxy DX33, new coax, and new Wilson 2000. Threw the meter on it, ended up trimming the whip down quite a bit, couldnt get lower then 2.5 on the meter. I rolled with it. Still ticking me off though as usual with this set up in my Peterbilt I got them down much lower. This Wilson has the 5” shaft. I’ve ordered a 10” shaft to get the coil higher above the steel cab, and new whip. Any tips at all or what I’m doing wrong. Running a single Antanea on pass side.
     
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  3. Night Stalker10

    Night Stalker10 Road Train Member

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    Sounds like you need some bonding in your future. Here's some good reading to help you.

    Bonding

    Like most big trucks today, you have an RF ground problem. Its possible you may have cut too much off the antenna before realizing there was a problem. The best tool to have is an antenna analyzer. Well worth the money and much better than a cheap swr meter. Just FYI.
     
  4. PSM379

    PSM379 Medium Load Member

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    seems like a good idea this is a older truck though, normal west coast mirror set up, simple Anatanea mount on mirror, I will definitely look into what you recommend thank you.
     
  5. Hatt91

    Hatt91 Light Load Member

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    Make sure you’re not near any buildings or vehicles when your check your SWR. Middle of an empty parking lot will do.
     
  6. Night Stalker10

    Night Stalker10 Road Train Member

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    Oh okay, usually older trucks aren't as bad as the newer trucks as far as tuning antennas. Do you own an ohm meter? It's another good tool to have when it comes to checking coax and connectors for shorts or opens.
    Also using the ohm meter to test the mirror mount. There should be a nylon washer that needs to be installed correctly on the mount too. It sounds like you are using an external swr meter, which is good. The swr reading is 2.5, does the reading get higher if you raise the Steele whip up, or does it stay the same? A 10 inch shaft maybe what that antenna needs too. It will be interesting to see if it helps or not. Also don't worry about an swr of 1:1 reading, 1:5 is just fine.
     
  7. rabbiporkchop

    rabbiporkchop Road Train Member

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    Check the DC resistance from your antenna mount to the radio ground and you should see zero ohms. If you see anything other than zero ohms, that's your problem that you need to fix before you can adjust the antenna.
     
  8. varmonter

    varmonter Bobtail Member

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    That's good advice.. do you mean from the mount to the negative battery terminal or where the radio black wire is grounded if not the same place..??
     
  9. Ridgeline

    Ridgeline Road Train Member

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    No he means the antenna mount where the antenna is mounted on the truck and where the coax connects to.

    some are so cheaply made that the insulator (usually recycled nylon) show a resistance which means there is something conductive in it and will not allow the antenna to tune right.
     
  10. jessejamesdallas

    jessejamesdallas Road Train Member

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    I would opt for the drivers side...."Trees" are on the passenger side!
     
  11. craig_sez

    craig_sez Road Train Member

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    Chk and see if you get the same swr through all the 40 ch,if yes its a rf gnd...
    Seeing its the older style,chk to see if there are plastic bushings between the mirror arm bracket AND see if you have the plastic bushing is between top part of ant stud and antenna..Notice where plastic washer is on the mount..
     

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