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Building a half wave coaxial antenna

Discussion in 'CB Antennas' started by Bow, Mar 7, 2012.

  1. Bow

    Bow Bastard Modulation

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    Well.. I decided to try my hand at building a vertical antenna for the house.

    I was looking at designs on line and stumbled on this page: 6 Meter Repeater Antenna 1/2 Wave Coaxial Vertical Antenna Design

    The current idea is:
    102" Radio Shack whip for the stinger
    3/8 x 24 Feed Through for the stinger mounting
    1" x 10' copper for the inner coax run
    1.5" x 10' copper for the outer lower half of the dipole
    1" cap
    1.5" cap

    I plan on constructing it just like the website shows, running the coax (RG-8X up through the inner 1" pipe), but I have a question about scaling it for 11/10 meters...

    I am thinking the the 1.5" lower/outer pipe makes the other half of the dipole, and should be cut to length (around 102") to match the 102" on the stinger.

    I realize I am basically building a Shakespeare Big Stick, but building is a lot more entertaining than buying (cheaper too), and the copper will blend in nicely with the surrounding landscape...



    My question is:
    Is the length of the inner 1" pipe critical to the operation of the antenna?
    If so, how long does it need to be while still allowing for mounting?

    Thanks
     
    #1
  2. W5LZ

    W5LZ Crotchety Old Bastard

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    No, the length isn't critical. It's used for support so as long as it's long enough to allow for adequate mounting it should work fine. A little longer than necessary would probably be a good idea.
    - 'Doc
     
    #2
  3. Bow

    Bow Bastard Modulation

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    Outstanding!

    Thanks for the Reply Doc.

    I have to go get some 1.5" copper and a cap for it... :D
     
    #3
  4. vo1ks

    vo1ks Active Member

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    I built something similar for 2 meters. It used 1-1/2 inch copper outer and 3/4 inch inner copper pipe. The whip was a 3/8 inch hole mount, black half circle. Worked very well.
     
    #4
  5. Bow

    Bow Bastard Modulation

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    Great, thanks for the info...

    What is a "Black Half Circle"?
     
    #5
  6. vo1ks

    vo1ks Active Member

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    Hmm. I need a picture... Anyone know what I'm talking about??

    I used to have one in the middle of the roof of my car. They used to be very popular on taxis, sometimes attached to a right angle bracket bolted to the fender next to the hood or trunk.

    It uses a 3/8 inch hole mount, then a black plastic part that screws onto the mount, and the whip goes on top. Coax feeds up through center, shield clamped in place and the center conductor twists around under the whip.

    That's what went on top of the copper sleeve...
     
    #6
  7. Bow

    Bow Bastard Modulation

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    Ball Mount?

    [​IMG]
     
    #7
  8. vo1ks

    vo1ks Active Member

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    Not even close. It's a half sphere, about 1-1/2 inches diameter. Made of hard black plastic. The VHF whip screws onto the top.
     
    #8
  9. W5LZ

    W5LZ Crotchety Old Bastard

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    Sounds like some sort of 'beehive' or stud mount. I think I can remember seeing them but it's been a long time ago. Also remember them turning sort of grey'ish over time. They worked.
    - 'Doc
     
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  10. HomerBB

    HomerBB Well-Known Member

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    If possible, make some photos as you go all the way to the final antenna.

    Thanks,
    Homer
     
    #10

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