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My Latest Antenna Project

Discussion in 'Home Brew' started by unit_399, Aug 21, 2011.

  1. unit_399

    unit_399 EL CAPO

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    About 9 months ago, I built a 2-element quad antenna. It worked well until the plastic wire retainers on the ends of the spreader arms broke. I pulled down the antenna and made heavier retainers. 3 weeks later one of the bamboo spreader arms broke, so I hauled it down again. All of the bamboo spreaders were brittle and cracked even though I had given them several coats of spar varnish. So, I decided to redo the whole thing. 6 months have passed, and it's finally done.



    PICT0045a.JPG

    The new quad has spreaders made from extruded aluminum tubing and fiberglas rod. Also, it's a direct feed, but I made a connection box so I can add a 1/4 wavelength of 75 ohm cable if it's necessary. I'm going to put it up on Monday. Hopefully this one will last a little longer.

    PICT0041a.JPG

    PICT0035A.JPG

    PICT0043a.JPG

    - 399
     
    #1 unit_399, Aug 21, 2011
    Last edited: Aug 21, 2011

  2. BJ radionut

    BJ radionut Supporting Member and 6m addict

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    399: Love it...looking good OM....
    Nice scenery at your place too...long way from INDY "ye"!;)
    All the Best
    BJ
     
  3. wavrider

    wavrider W9WDX Amateur Radio Club Member

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    Looks great, Good job and thanks for the pictures.
     
  4. HomerBB

    HomerBB Sr. Member

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    That thing looks great, J.J.
    Makes me want to build another one, too.
     
  5. 74IN

    74IN Well-Known Member

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    No kidding.

    We have cows and horses here, but mountains? Here at the lake, we have MT. Baldy, but it's just a big sandpile.

    What band is the antenna for, without a reference point, it's hard to tell it's size.

    Looks very well built.
     
  6. unit_399

    unit_399 EL CAPO

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    11 meters.

    BTW ... on the initial build I used #12 enameled wire that I got from a motor rewind shop. When I pulled the antenna down, a lot of the enamel was missing and the bare copper was corroded. I handled the wire very carefully when assembling the antenna (no kinks, stretching, etc.) I guess the combo of mucho rain and sun down here was too much for it. So this time I used wire with thin teflon insulation. We'll see how it holds up.

    - J.J.
     
  7. n0zna

    n0zna Digital master

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    nice,i am going to build a quad or half square antenna...73s from missouri,de jw
     
  8. RickC.

    RickC. Hopeless antenna junkie

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    Me likey! Good job. Keep us posted on how it handles ice.


    Rick
     
  9. very nice and clean looking . im really looking forward to hearing your results with it (y)
    nice piece of gods country you got there , beautiful mountain view too . (y)
     
  10. Mr Clean

    Mr Clean Active Member

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    Very nice! Hope to get to hear it.
     
  11. unit_399

    unit_399 EL CAPO

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    Finally got caught up enough to pull the guys out of the fields for half a day to get the quad put up. Night and day difference between it and my dipole. 1.3:1 swr on 27.385. I'm very satisfied with the way this project worked out

    - 399


    IMG_1035a.JPG

    FINISHED UP JUST BEFORE THE STORM BLEW IN

    IMG_1033a.JPG
     
  12. Needle Bender

    Needle Bender ...he thinks it's funny that I stepped in it

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    looks good. how did you tune it for best performance? ill have to listen for you. what freq do you use for sideband? when i bilt my quad i just drilled a 5/8 inch hole all the way thru the 1 3/4 inch boom and used 2 feet of 5/8 16th wall tubing and drilled crosswise next to it for the other spreader tube. i had to drill thru the boom crosswise in the middle of each 5/8 tube for a small bolt to lock them from sliding out of the boom holes. i slotted the ends of the 5/8 tubing and used a automotive compresson clamp to squeez down on the 6 foot long 1/2 inch around fiberglass rod spreaders to tighten the wire. it looks real clean and works perfect
     
  13. man that looks nice . did you notice much or any difference in the noise floor ? did you wind up needing to use 9 ft of 75 ohm coax for it to tune ? what are your wire lengths for the elements ?
     
  14. unit_399

    unit_399 EL CAPO

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    Booty -

    I designed the antenna for 27.385, and the wire length (driven element) is 36.699 feet. Reflector is about 10% longer. At first, swr was off the scale, but when I added the 75 ohm stub it dropped down to 1.3. The 75 ohm stub is 9.2 feet long. I haven't done any tests, but weak signals came up by about 1 to 2 S-units or so over my dipole. Guys I talk to all the time in the US said I also came up by 1 - 2 S-units on their meters. F/B Ratio isn't important to me because there are very few other (if any) 11 meter operators here.

    - 399
     
  15. Needle Bender

    Needle Bender ...he thinks it's funny that I stepped in it

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    399 i think you maybe missed my post above bootys. my wire was 432 inches for the driven and 448 for the reflecter. a 1/4 wave of 75ohm should be 9 feet times its velocity facter or more like 81 inches if its vf is 75%. stations in front would hit with 20 and in back they would hit about a s4. the better the tuning of the reflecter the more forward gain you get
     

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