Cb interference with am/fm

Discussion in 'Electronics' started by jeeptorino68, May 17, 2018.

  1. jeeptorino68

    jeeptorino68 Full Access Member

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    Just installed a Uniden bearcat cmx560 (an all in the handset unit) ran that through ~9ft of coax to my firestik moutn and to my ~4ft firestik classic antenna.

    hooked up the SWR meter first (of course) and followed its instructions. SWR reading is just above 1. great (seems a bit too good to be true, but whatever)

    i have set up several CBs in several rigs the same way without issue.

    here is the issue(s) in this setup

    when i key the mic (to transmit) the AM/FM radio gets quieter, the volume. the two units are not tied together, other than chassis ground...any ideas?

    i have not tried to receive a known signal, but all channels i was receiving static unless i changed the squelch to level 2 or 3 (this unit only has 1, 2, or 3 for the squelch, which is frustrating)

    bad radio ground? bad antenna ground?

    ideas?

    tonight i will try sending from one of my rigs to another and see what happens.
     
  2. profdlp

    profdlp Grouchy Old Cuss

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    Where are you getting power for the CB? I might try temporarily tapping in somewhere else and see if it makes a difference.
     
  3. jeeptorino68

    jeeptorino68 Full Access Member

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    Well I think I found it. Started probing my antenna wires and they have continuity between the two...thats not right....soy or check my,mounting and its good. Just like all my other rigs. Unhook the radio and probe the connector for the cable there. No continuity...ok...wierd. Probe the radio and the antenna connection is a complete circuit. Must be something wrong internally on the radio
     
  4. profdlp

    profdlp Grouchy Old Cuss

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    That stinks. :(
     
  5. jeeptorino68

    jeeptorino68 Full Access Member

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    Yup. Seems pretty obvious. I don't think there is any way/reason the coax output k,,the radio would have both sides of it connected and a complete circuit. Brand new radio...
     
  6. gicts

    gicts New Member

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    Could it be a lack of electricity (ie wired into the car lighter)?

    On a side note, how'd you run the coax into the jeep? I mocked up a bracket for an antenna and am struggling whether I should drill a hole in the pillar, use the brake light hole, or just run it through the door gasket.
    [​IMG]
     
  7. profdlp

    profdlp Grouchy Old Cuss

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    I drilled the coax hole through the frame in what would be just to the right of the lower right-hand corner of the gasket area. It will come up under the plastic trim in the cargo bay, making it easy to run the rest of the way to the dash area. (Which I presume is where you are locating the CB.)