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Building 102' vertical Antenna for 11 meters...

Discussion in 'Home Brew' started by T23, Nov 8, 2010.

  1. T23

    T23 Active Member

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    Building a 102' vertical for 11 meters.



    I am building a vertical for 11 meters. I am building it on top of a camera tripod, I have taken the camera bit of the top of it, and now there a threded hole for a bolt to screw into, the antenna base screws into this which consists of a piece of all-thread 2 nuts, washer, and a disk with a hole in the center for all that to go through, then 2 radiator clamps hold the PVC pipe to the top of the all-thread, that holds the 102' piece of wire for the antenna. The antenna wire is soldered to the washer and so is the center of the feed coax, the braid is crimped onto the disk through a loop, and there are 2 plastic and rubber washers that isolate the the center and the ground.

    Any suggestions/comments? :laugh:

    T23
     

  2. W5LZ

    W5LZ Crotchety Old Bastard

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    I would suggest a starting length of about 105 inches so it can be trimmed/tuned. That's only slightly too long.
    - 'Doc
     
  3. office888

    office888 Active Member

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    102'? You mean "?

    ' = ft, " = inches.

    This.

    You could use a piece of conduit instead if you want this to be a more permanent install? Good luck on your project though, radio is all about building and tinkering!
     
  4. T23

    T23 Active Member

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    Good sugestions.... I also wanted to add that I was going to use plumbing tape to isolate the all-thread from the stand and the disk (which is the ground plane ). How small do they make conduit?


    T23
     
  5. T23

    T23 Active Member

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    I meant 102 inches...:laugh:

    It would take ALOT of PVC to do 102 feet and probably would not work so well.:LOL:

    T23
     
  6. W5LZ

    W5LZ Crotchety Old Bastard

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    T23,
    It'd be some kind'a tall, wouldn't it? But then, that'd be some kind'a camera tripod too.

    No idea about the smaller sizes of conduit, I think 1 inch is about the smallest 1've ever seen. You might think about that plumber's thread tape again too(if that's the kind you meant), sometimes that isn't as good an insulator as it seems. That would depend a lot on how tight the connection is made. I can remember seeing the metal showing through that tape when the connection was un-done before.
    PVC comes in several sizes and I would think that finding one that's a tight fit with some kind of conduit shouldn't be that 'rare'. There's more than just one way to do that so whatever works for you.
    - 'Doc
     
  7. T23

    T23 Active Member

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    I was wondering...How would I determine what kinda wattage I could put through this?


    T23
     
  8. W5LZ

    W5LZ Crotchety Old Bastard

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    What kind of power? A lot of that depends on how 'good' the insulators used in the antenna's construction are. What's used for the elements, wire, conduit, whatever, has very little to do with it till power get's into the multi-kilowatt ranges (>2 or 3K+/-). If you ever get to that stage I doubt if you'll keep using that home-made antenna.
    - 'Doc
     
  9. Highlander_821

    Highlander_821 Amour d'Ecosse

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    Do you have some kind of counterpoise or ground radial system for this antenna? If all you have is the single 102 inch element to work with, I don't think you will get very good results. A quarter wave radiator like that would need at least one counterpoise wire of about the same length to work properly.
     
  10. T23

    T23 Active Member

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    Correct me if I am wrong...But what your saying is I need an equal amount of ground plane to antenna length? I have never built an antenna before so this is new to me.


    T23
     
  11. Beetle

    Beetle Sr. Member

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    Correct. A 1/4 wavelength vertical needs a ground plane at least 1/4 wavelength, ideally arranged in a circle around the base of the antenna. Since the base of your antenna will be more than just a very few inches off the ground, I wouldn't use fewer than four, spaced 90 degrees apart, and angled down. The angle will probably affect the feedpoint impedance to some degree; HOW MUCH is something you'll have to find out and deal with, making changes and seeing how one factor changes other factors. In other words, experimenting.
     
  12. #12 BOOTY MONSTER, Nov 8, 2010
    Last edited by a moderator: Nov 9, 2010
  13. packrat

    packrat Active Member

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    That teflon tape probably wont do you any good as an insulator. It is designed for the threads to cut right thru it, and the tape to just fill in the gap in the threads between the two pieces of pipe, but to still provide continuity.
     
  14. T23

    T23 Active Member

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    Any suggestions then...?


    T23
     
  15. HomerBB

    HomerBB Sr. Member

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    Try two all thread nipples with a PVC threaded coupling between them. Also, conduit comes as small as 1/2" diameter x 10' length.
     

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