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Overhead Coax run support?

Discussion in 'General Ham Radio Discussion' started by archjeb, Sep 28, 2018.

  1. archjeb

    archjeb Member

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    Folks,

    I'm thinking now to get away from all the noise sources in the house, that I need to get the antenna as far away from the house as possible.

    That being said, because of retaining walls in the way, I want to go overhead with LMR-400 cable from the house roof eave to a Pressure treated wood post that I'll have about 50' from the house.



    What is the best cable / rope to use to support this coax on that length of run? Antenna cord from Ham Radio Outlet? Or guy wire?
    Is zip tying it to the wire/rope adequate enough (assuming I don't do it tight pinching the Coax)? I'm thinking the black/ UV protected zip ties.

    Thanks,

    -J
     

  2. sp5it

    sp5it Master of puppets

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    What are you going to do to avoid coax be acting like antenna?
    Mike
     
  3. BJ radionut

    BJ radionut Supporting Member and 6m addict

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  4. jessejamesdallas

    jessejamesdallas Sr. Member

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    Don't think moving the antenna 50' away from the house is going to do much of anything to eliminate noise...If anything it's going to cause more line-loss because of the added distance...Be better to go after the noise source and try to filter it out.
     
    Hurricane145 and Road Squawker like this.
  5. loosecannon

    loosecannon Sr. Member

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    if you are trying to get less noise from your house, go up not over, and use an antenna with a ground plane.
    LC
     
    Hurricane145 likes this.
  6. archjeb

    archjeb Member

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    I follow you. But when I tested the antenna horizontally away from house about 30' the noise dropped off substantially. So I was hoping that 50' would even be better.

    Some of the noise sources are work equipment that I can't shutdown. They use switching power supplies that appear to be the source of some of this noise.

    What is interesting though, if I put a dummy load on the end of the feedline, I have no noise...S0 on meter. Once the antenna is attached, then 80 & 40 meters is at S9 with noise/hash - unusable.

    With AM receiver in hand and walking around the house to detect noise, it's like the AC wiring in the house is one big tranmitter!
     
  7. nomadradio

    nomadradio Analog Retentive

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    Suspending your coax up in the air creates the risk of the "antenna" effect.

    The outside surface of the coax braid becomes an antenna if you don't keep it on the ground, or (better) under it.

    Folks who would shorten a coax run by hanging it off the tower halfway down, running over a roof or in the air will have problems with RF in the radio room. All the RF that gets picked up on the outside of the coax comes back down into the building.

    Best to bring it all the way down to ground level at the base of the tower.

    73
     
    Shadetree Mechanic likes this.
  8. archjeb

    archjeb Member

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    nomadradio, your comment is making me think that maybe that is why I had a much lower noise floor when the antenna 30' away was because the feedline was laying on the ground.

    I guess the ultimate test would be to move the antenna and test the difference between feedline on the ground and suspended...

    -J
     
  9. nomadradio

    nomadradio Analog Retentive

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    Um, this noise problem..

    Doesn't get quiet during and after a soaking rainfall, does it?

    73
     

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