Building a Hex-Beam, need some input.

Discussion in 'Antennas, Feedlines, Towers & Rotors' started by N4FMG, Aug 12, 2012.

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  1. N4FMG

    N4FMG Ham Member

    I've gotten all the parts together to start the construction.
    I've built up a moxon 20m beam to get an Idea on construction and tuning.
    The only problem I have going on is the wire lengths. I'm using #14 awg insulated
    wire and was wondering if there is a conversion factor out there for using insul wire.
    I had to shorten all the elements on my moxon due to the insulation on the wire
    I think it was around .962 that I ended up with.

    Anyone know if this is correct? or have the correct conversion factor?
    thanks
     
  2. KF7ORO

    KF7ORO Ham Member

    The exact length you end up with depends on quite a few things and the insulation is only one of them. Insulated wire will end up shorter than bare wire but the best way to build it is start with the wire a little long and trim it to resonance in the actual environment where it'll be used.
     
  3. NH7RO

    NH7RO Ham Member

    While there is no set formula; most will tell you that 3-5% shorter is right for insulated wire over bare. So your 3.8% difference seems to be right on target.

    How did you like your Moxon test antenna? I miss the three that I had until my recent relocation. Decent gain and directivity out of a compact package.

    If you are building your own Hex Beam from scratch, check out this fellow's beautiful homebrew Hex before you start---you might get some ideas on nifty bits to use:

    http://www.kg4jjh.com/hexbeam.html

    I would also recommend checking out the new folding hex beam being made and sold in Germany in case you might want to try a flat hex instead of the usual upswept array (the feedpoint/choke balun point is thus close to all the elements this way besides being portable and more compact).

    http://www.foldingantennas.com/gb.html

    Have fun and enjoy your build, 73, Jeff
     
  4. G3TXQ

    G3TXQ Ham Member

  5. N4FMG

    N4FMG Ham Member

    The Moxon has been great. I've made a lot of contacts with it that I couldn't do before with my 5BTV, Might be able to make some of them with the ZS6BKW
    that I have up but the lobes are in the worng direction for europe.
    The swr on the moxon is great 1.1 at 14.200 to 1.3/1.4 at 14.350

    I'll keep the Moxon for the time being till I see how the hex performs.
    I'm really only building the hex to get a multi-band solution up. I've not seen any good things about a multi band Moxon
    Thanks again for the help.
    Now to finish the fabrication for the hex.
    Have the base and center pole and supports built. Just have to get a few more 15' crappie poles . I had 4 spare so off to
    wally wolrd for some $10.00 poles.
     
  6. KD8D

    KD8D Ham Member

    I rebuilt my hex beam this summer with the crappie poles from Cabela's. The June 29 wind storm that came through WV completely destroyed the hex, I wish I would have taken pictures all six elements were pointing the same direction. I just got it back up by rebuilding again but used the fiberglass spreaders from http://www.mgs4u.com/hexbeam-kit.htm . The kit is only $119+s&h it is well worth the money.
     
  7. NH7RO

    NH7RO Ham Member

    I was just about to chime in with the Max Gain Systems recommendation...

    73, Jeff
     
  8. N4FMG

    N4FMG Ham Member

    I"ll be up at the Huntsville hamfest and I might just pick up a set of fiber glass spreaders.
    I dont really like how the carppie poles bend anyway.
    They are great for my Moxon but I have it in a Yagi config.
     
  9. NH7RO

    NH7RO Ham Member

    The only negative thing I've ever heard about MGS is their expensive shipping (due to a minimum order policy, I believe). Although I've never used any of their fiberglass I wouldn't hesitate buying some anytime good quality FG was needed (see AE7F's homebrewed spiderbeam thread for his MGS FG praise).

    If you are close to MGS when you go to Huntsville it then becomes a no-brainer! If I were in your shoes I'd probably buy a truckload!

    I used to use Wal-Mart fishing poles for my Moxons when I was in KH6 and couldn't get anything else (other than local bamboo but that's another story). Now that I am back on the mainland I don't have the situation where I can put up as many antennas as I want so it may be a long time before I'm building another Moxon or trying out a hex. If the situation changes I'll try out MGS Type 1L (lightweight) spreaders for sure.

    Imagine you know this already but be sure to spraypaint whatever you use for spreaders as UV will deteriorate even the best fiberglass.

    Although the general consensus is that multiband Moxons don't work, there are some duoband and tri-band Moxons that do play well. Check out The Moxon Antenna Project website if you haven't already and take a look around; I believe that's where I saw them. But with only a half a db or so difference in gain and a few in F/B I'd easily opt for a hex like yourself. I am intrigued by that new folding Moxon (flat and only 13 lbs vs 25 lbs and upswept) enough to want to give one a go sometime.

    I'll stay tuned as I am always interested in wire beams. Have fun in Huntsville!

    73, Jeff
     
  10. G3TXQ

    G3TXQ Ham Member

    Folding Moxon, or folding hexbeam?

    Steve G3TXQ
     
  11. NH7RO

    NH7RO Ham Member

    Oops! I meant folding hex beam---it's just that I always have Moxon-on-the-Brain syndrome aka Chronic Moxonitis...

    73, Jeff
     
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