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Thread: Aluminum Antenna Fabrication

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  1. #1
    Join Date
    Mar 2010
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    Grays Harbor WA
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    521

    Default Aluminum Antenna Fabrication

    Hey I've been looking at doing some antenna work, but I am handicapped, amongst many other things, by the fact that I don't have any welding skills or equipment. Since I don't really want to put out bundles of money to hire a welder to join the aluminum, I've been looking around at various other options.

    Alutite -- aparently only available in Sweden
    DuraFix -- also seems to be scarce
    Alumaloy -- this seems to be readily available and is supposed to work better than Alumaweld.

    Has anyone used this type of stuff to "propane weld" aluminum?

  2. #2

    Default

    Maybe we don't have enough information - why are you trying to weld aluminum? just in general, mechanical joints tend to be much more common in this application.

    If it's real structural welding, you probably need a pro who can do shielded arc welding - aluminum is pretty tricky as I understand it.
    This Space Intentionally Left Blank

  3. #3

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    I wonder that, also. Structural assemblies like towers and bicycles and stuff are usually heliarc welded, but why would an antenna need that?

    Most beam antennas are made from aluminum and don't include any welding.
    A government which robs Peter to pay Paul can always depend on the support of Paul.

    -- George Bernard Shaw

  4. #4

    Default

    Quote Originally Posted by N7GH View Post
    Hey I've been looking at doing some antenna work, but I am handicapped, amongst many other things, by the fact that I don't have any welding skills or equipment. Since I don't really want to put out bundles of money to hire a welder to join the aluminum, I've been looking around at various other options.

    Alutite -- aparently only available in Sweden
    DuraFix -- also seems to be scarce
    Alumaloy -- this seems to be readily available and is supposed to work better than Alumaweld.

    Has anyone used this type of stuff to "propane weld" aluminum?
    Normally clamps and screws are normal fixing for alloy antennas , I doubt you ned to weld anything once you think it through and if you do just a weld or two can be done by your local engineering shop

  5. #5
    Join Date
    Mar 2010
    Location
    Grays Harbor WA
    Posts
    521

    Default

    I'm making an copy of a DB224E antenna--usually used on repeaters and electrically all points of the antenna are at ground level: everything is literally welded together. Its a 4 bay loop. Each full wave loop is welded together, the loops are each welded to a small strut, each strut is welded to the main mast. It's all one big chunk of aluminum when your done. I had to do some pretty good experimentation before I would believe that the design was just not someone trying to pull my leg, but it really works, even though, it's electrically at ground level. They are famous for taking lightning strikes and surviving.

    Quote Originally Posted by WB2WIK View Post
    I wonder that, also. Structural assemblies like towers and bicycles and stuff are usually heliarc welded, but why would an antenna need that?

    Most beam antennas are made from aluminum and don't include any welding.

  6. #6
    Join Date
    Jan 2008
    Location
    St. Mary's County Md since 2000
    Posts
    7,485

    Default

    You are trying to replicate a very expensive commercial grade antenna. There are no short cuts. You'll have to use commercial grade welding methods.

    Either enroll in a welding curriculum, or make up drawings and take them to a machine shop or welding shop.

    p.s. I've tried those 'weld aluminum with a propane torch' sticks and found them unusable and highly prone to corrosion.
    Last edited by KB4QAA; 09-07-2012 at 12:06 PM.
    Bos Ebal Nolom! "South African Cows on a mountain in the West Bank!"

  7. #7

    Post

    Decibel Products DB-224E Specification Sheet (Andrew brand name spec sheet)
    ​Still manufactured in North Texas
    http://www.repeater-builder.com/db/p...t-(andrew).pdf

    DB-224E Detailed diagram (2005), from Doug Zastrow, WBUPJ
    Element detail and phasing harness
    http://www.repeater-builder.com/db/p...diagram-dz.pdf

    Catalog page:
    http://www.repeater-builder.com/db/p...sheet-(db).pdf

    DB-224 Installation instructions (2003)
    http://www.repeater-builder.com/db/p...tion-sheet.pdf

    ==
    dB Spectra
    http://www.dbspectra.com/pages/About-Us.html
    Last edited by W9GB; 09-07-2012 at 02:31 PM.
    Nullius in verba

  8. #8

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    Quote Originally Posted by N7GH View Post
    I'm making an copy of a DB224E antenna
    Yeah, I'm very familiar with that antenna and have owned several of them over the years (not homebrew, though) for repeaters.

    You can skip the welding if you replace the aluminum with copper tubing and just solder it with silver solder. That would make it slightly heavier, but not a lot. Copper's easy. BTW no real reason I can think of to weld the elements to the supporting mast; the most popular version of the DB-224 doesn't do that -- the mast is separate and the elements clamp to it. That's so the same antenna can be used on a tower leg instead of a mast, and in many installations that's exactly what's done. It's still just as grounded.
    A government which robs Peter to pay Paul can always depend on the support of Paul.

    -- George Bernard Shaw

  9. #9

    Default

    The aluminum brazing rod sold at Home Depot works very well. The joints I have made are stronger than the aluminum tubing. But it can barely be brazed using a propane torch. A MAP gas torch is the thing to use.

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