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help with my CB

Discussion in 'CB Radio Forum' started by jrouzaut, Mar 18, 2019.

Page 1 of 2
  1. Mar 18, 2019 #1
    jrouzaut

    jrouzaut Bobtail Member

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    Mar 18, 2019
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    Hi There, I have a cobra 29NW with dual firestik 4ft antenna's. Very short range radio works fine, short range meaning in sight. With the built in SWR meter I am registering about 1.5 ish with it being slightly higher on channel 1 than 40. I tried it with a seperate SWR meter and it is registering over 3. I have it temporarily grounded with 12 guage automotive wire until grounding straps come in the mail. The antenna's are mounted to a back rack on an aluminum pickup bed. 2017 F-250. Can anybody tell me which meter to believe and help with range?
     
    jrouzaut, Mar 18, 2019
    jrouzaut, Mar 18, 2019
    #1
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  3. Mar 18, 2019 #2
    YMItrucking

    YMItrucking Light Load Member

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    If I'm not mistaken, co phase antennas need to be 9' apart. Try using just one of the antennas and tune it.
     
    YMItrucking, Mar 18, 2019
    YMItrucking, Mar 18, 2019
    #2
  4. Mar 18, 2019 #3
    jessejamesdallas

    jessejamesdallas Road Train Member

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    Are you using a Co-phase coax harness? Have to use 75ohm coax cable to make it work...Second, on a pick-up there's no way your going to get the correct spacing for co-phased antennas.
     
    jessejamesdallas, Mar 18, 2019
    jessejamesdallas, Mar 18, 2019
    #3
    rabbiporkchop and jrouzaut Thank this.
  5. Mar 18, 2019 #4
    jrouzaut

    jrouzaut Bobtail Member

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    Mar 18, 2019
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    Using the co phase 18ft cable that came with the antenna's as a kit. I wonder if you can use the co phase cable and just connect one antenna, I read somewhere a minimum of 5ft apart.
     
    jrouzaut, Mar 18, 2019
    jrouzaut, Mar 18, 2019
    #4
  7. Mar 18, 2019 #5
    Ridgeline

    Ridgeline Road Train Member

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    no you have to have a load on both ends of the coax. I would just get a length of coax - anything over say six feet with end on it and hook up just one antenna to see what it is doing.
     
    Ridgeline, Mar 18, 2019
    Ridgeline, Mar 18, 2019
    #5
    rabbiporkchop and jessejamesdallas Thank this.
  8. Mar 21, 2019 #6
    craig_sez

    craig_sez Road Train Member

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    Yes to be at its best but i have been told it will "work" if closer together..When i do stuff i dont like it to just "work",but thats me.
     
    craig_sez, Mar 21, 2019
    craig_sez, Mar 21, 2019
    #6
  9. Mar 22, 2019 #7
    rabbiporkchop

    rabbiporkchop Road Train Member

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    I've run a pair of antennas 102" apart with excellent results. I've heard 108" would be better. If ground potential is equal, I tune both elements simultaneously. If I tune one, and then the other, they usually end up being too short when the second one is added.
     
    rabbiporkchop, Mar 22, 2019
    rabbiporkchop, Mar 22, 2019
    #7
    Night Stalker10 Thanks this.
  10. Mar 22, 2019 #8
    Night Stalker10

    Night Stalker10 Road Train Member

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    From what I understand the way you mentioned, is the correct way to tune Co-phased antennas. You treat both antenna as if they are one antenna. If you trim a quarter inch off one antenna, you need to trim a quarter inch off the other one. Basically the same principle as tuning a dipole antenna.
     
    Night Stalker10, Mar 22, 2019
    Night Stalker10, Mar 22, 2019
    #8
  11. Mar 23, 2019 #9
    Slowmover1

    Slowmover1 Road Train Member

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    I just use separate single coax and tune each antenna singly. SWR is fine once installed into co-phase setup.
     
    Slowmover1, Mar 23, 2019
    Slowmover1, Mar 23, 2019
    #9
  12. Mar 24, 2019 #10
    rabbiporkchop

    rabbiporkchop Road Train Member

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    Wapwallopen, Pa
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    That only works if the ground potential is equal between both antennas. If one of them has a bad ground it's going to drive you nuts trying to figure out the problem.
     
    rabbiporkchop, Mar 24, 2019
    rabbiporkchop, Mar 24, 2019
    #10
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