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Antenna Help

Discussion in 'CB Antennas' started by jkp1, Oct 15, 2018.

  1. jkp1

    jkp1 Member

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    Hey guys,



    I'm fairly new to CBing. Actually started using one as an Oversize Load Escort. I had Uniden 520 with a Wilson 1000 magmount, which worked fine. But being OCD, I want to learn and improve the system. Right now, I'm focusing on the antenna. I bought a MFJ 259-C, and have been playing with it. My question for today is what should my antenna line loss be. I have readings between 7 and 8 db. Isn't that pretty high?
     

  2. Captain Kilowatt

    Captain Kilowatt Professional Amateur
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    Yeah that us way too much. Are you measuring line loss with the antenna connected? The far end of the cable should be open BTW.
     
  3. nomadradio

    nomadradio Analog Retentive

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    I don't think you have a way to disconnect that antenna from the coax.

    The "coax loss" measurement can only be performed with the coax disconnected at the far end from the analyzer.

    Leaving the antenna connected will disrupt this measurement and make the reading meaningless.

    73
     
  4. Captain Kilowatt

    Captain Kilowatt Professional Amateur
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    Yeah now I see the antenna type. Missed that the first time around. Like I said the antenna can not be connected when doing line loss measurements.
     
  5. jkp1

    jkp1 Member

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    Ok. Thanks. I assumed I could measure the antenna and cable as a unit. I can remove the coil and mast. Will that work?
     
  6. rabbiporkchop

    rabbiporkchop Well-Known Member

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    That should work fine
     
  7. jkp1

    jkp1 Member

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    Thanks RPC
     
  8. M0GVZ

    M0GVZ Sr. Member

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    OK if you want to improve the antenna then do this:

    1) Bin the magmount.

    2) Go to www.k0bg.com, read up the sections on mounting, grounding and bonding.

    3) Choose an antenna with a stainless steel whip such as a Sirio Performer 5000 that can use a fixed mount and get a puck mount from Breedlove Mounts, expensive but they'll outlive the vehicle. Drill a hole in the middle of the roof, install fixed mount.

    4) Do bonding.

    If you measure the frequency where X=0 before you start doing bonding then you'll notice as you do the bonding, without adjusting the antenna the frequency where X=0 starts to drop and this is proof you are improving your RF ground. You should find that when you've finished bonding that the antenna SWR is below the CB band, there's not enough adjustment and you have to physically cut the whip.
     
    Slowmover likes this.
  9. jkp1

    jkp1 Member

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    Hey thanks MOGVZ. I've read everything on k0bg's sight, some of it multiple times. I have a Sirio antenna, I just haven't commited to drilling the hole. I have done some bonding, but I didn't have the MFJ when I did it, so I can't do a before and after.

    I think I do need a longer whip. I had the antenna tuned with an analyzer once and with resonance centered on channel 20, SWR's were higher on 40 than on 1. DA me shortened the mast to flatten out the SWR's instead of leaving it resonant.

    I've been busy and not taken the time to mess with the antenna much. The next project is to try and see if if it makes a difference where on the roof the antenna is mounted. The roof has ribs on it and I can't mount it directly in the center. The Breedlove mount would have to sit off to one side. I've thought about mounting it near the back, behind the ribs. Another advantage off that location is not having to take down the headliner.

    I've also been undecided between LM400 and RG8X coax. With the RG8X I could make a choke, not smooch with the LM400.

    Thanks again for the input. When I get time to do some more experimenting, I'd probably have more questions.
     
  10. undertaker

    undertaker Undertaker

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    Drill the hole I did on mine 2017 f150 drilled in the center if the rib no problem...

    SWR 1.4 good enough
     
    357magnum likes this.
  11. jkp1

    jkp1 Member

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    Could you post a pic?
     
  12. 357magnum

    357magnum Well-Known Member

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    Sorry Bobby , I cringe every time I think about you drilling that hole !:LOL: My wife has a new Lariat ( $$$ ) . But that is the way to do it right !(y) 73 , Leo
     
    Rwb and undertaker like this.
  13. jkp1

    jkp1 Member

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    My truck is a 13 with over 200,000 on it. It's far from perfect. At this point, it really won't matter.
     
    357magnum and Rwb like this.
  14. Slowmover

    Slowmover Active Member

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    Given the damage a mag mount could do (it’s potential), the only pain with a proper antenna mount is a specialized drill bit.

    But, pain will turn to pleasure in re that sunnava who divorced your sister leaving her high & dry. Next week he’s back on night shift . . .
     

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