Homebrew HF multi-band log periodic?

Discussion in 'Antennas, Feedlines, Towers & Rotors' started by AE7F, Dec 27, 2011.

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  1. AE7F

    AE7F Ham Member QRZ Page

    Anyone ever tried to build one?
     
  2. KC5FM

    KC5FM Ham Member QRZ Page

    I have not but here are plans, if you want to try yourself.

    73
     
  3. W9GB

    W9GB Ham Member QRZ Page

  4. AE7F

    AE7F Ham Member QRZ Page

    Very cool, thanks. This is interesting:
    loghf2big.jpg

     
  5. AE7F

    AE7F Ham Member QRZ Page

    Thanks. I have been looking at Tennadyne antennas for awhile (antenna comparisons.xls). You can see that I found the T6 to be a very, very nice antenna for the price and have been looking around for one.

     
  6. WB2WIK

    WB2WIK Premium Subscriber QRZ Page

    Unless you have access to the materials for very discounted cost, it would be hard to beat the price of even a new Tennadyne.

    Seamless aluminum 6061T6 alloy tubing is expensive, and the T6 uses a lot of it, including 24' of extruded square boom stock and about 160 feet of round tubing of various snug fitting diameters, plus several precision cut insulating blocks, thick machined PVC insulating blocks at the mast mounting point, etc. It would make an interesting project, but certainly not an inexpensive one.
     
  7. AE7F

    AE7F Ham Member QRZ Page

    Yeah, their pricing is good for the T6 but one does wonder what materials would cost for the aforementioned LP design.

    http://www.texastowers.com/aluminum_.htm

     
  8. KO6WB

    KO6WB Premium Subscriber QRZ Page

    The ARRL Antenna Handbook has detailed instructions also at least mine does. You could try that. You might also want to pick up a copy of the handbook, the older ones are somewhat better but I don't know if they have the LP plans in them.
    Hope this helps
    73
    Gary
     
  9. VK2FXXX

    VK2FXXX Ham Member QRZ Page

    Wire LPDA

    You might consider a wire type LPDA?
    Maybe a 40ft boom and 12+ elements.
    See Cebick W4RNL site for some big LPDA designs.
    If it does not work well take it all down and use the boom as another antenna mast!!
    The rear spreaders as the basis for a rotatable dipole etc.........
    I would love to try one one day.Might need a bigger back yard though!
    Good luck
    Brendan
     
  10. WB2WIK

    WB2WIK Premium Subscriber QRZ Page

    Using those costs, the aluminum tubing would run about $280. Then you'd have to cut it in three dozen places and drill it it 36 places to join the elements, and 12 more places in the booms to insert the elements. You'd still have to create mast to boom brackets, PVC insulating spacers, and the big PVC mast clamp insulators, plus add several dozen SS screws, bolts, etc.

    It could probably be built for about $350 worth of parts, not considering shipping costs for the tubing.
     
  11. VK2FXXX

    VK2FXXX Ham Member QRZ Page

  12. KO6WB

    KO6WB Premium Subscriber QRZ Page

    That is quite an antenna. It gives some additional thought to what is possible. There was a design that was featured in QST that used a spider type of support. Can't really remember when it was published and it has been awhile. The antenna was made from wire and it was a LPDA. At the time I was interested in that concept but I haven't had the room to put something like that up.
    May be things will change, who knows?
    73
    Gary
     
  13. AE7F

    AE7F Ham Member QRZ Page

    LPDA... interesting.... found some stuff that looks cheap but might pack a punch...

     
  14. AE7F

    AE7F Ham Member QRZ Page

    You just made it sound not too bad!

    Hardest part for me is that I can't see the aluminum tubing. If I could go pick sections off the shelf at the hardware store, knowing what I was getting, and that it would fit together.... If I find a local source for tubing watch out!

    The T6 is a great price as is. But add shipping and suggested hardware and chokes/baluns and the DIY vs commercial price gap starts to grow.

     
  15. VK2FXXX

    VK2FXXX Ham Member QRZ Page

    I had a whole bookmark folder full of links to LPDA stuff.
    Ill see if I can find the article about building a wire LPDA
    I have an old Australian made LPDA under the house that was given to me by a generous Ham.
    Just a little 6 element job ,needs some new centre insulators and tlc.
    I like the Idea of having 1 directional antenna for say 7-30mhz,
    Even with the compromises.
    Brendan
     
  16. VK2FXXX

    VK2FXXX Ham Member QRZ Page

  17. NH7RO

    NH7RO Ham Member QRZ Page

    Thanks for posting the Telerana link; seeing photos made me realize that that is certainly an easily doable DIY 5-band single feedline antenna, isn't it? I believe this same or similar design wire LPDA is also in the ARRL Antenna Book (sans photos), too. Probably wouldn't be too costly to make; the fiberglass spreaders and the welded steel hub would be the only parts costing much.

    With a 400-ohm characteristic impedance I wonder if a 9-1 balun would be better than the recommended 4-1 balun at the feedpoint?

    Thanks again for further food for [antenna] thought.

    73, Jeff
     
  18. WB2WIK

    WB2WIK Premium Subscriber QRZ Page

    The T6 is cheap to ship because it comes in a very short carton. That's why it's a whole lot of pieces to put together.

    Mine shipped to Los Angeles and I think the shipping was about $25. The T8 comes in the same size carton, it's just more pieces.

    You'd have to build a choke balun for any kind of LPDA whether you bought it or built it, so that's a draw. I just use the "RF choke" type current balun made of coax, as they recommend. It costs about $8 or so to build it. There isn't any extra hardware to buy, it comes with all the hardware you could need except for the balun and feedline.

    I build VHF-UHF antennas pretty often but wouldn't try building an HF LPDA unless I had a big machine shop and a lot of time. To pull this off with hand tools would just be too much work, for me.:eek:
     
  19. AE7F

    AE7F Ham Member QRZ Page

    Appreciate the input. Always helps.

    Drill press, chop saw, jig saw? Metal blades.... Shouldn't be too bad at all.

    However, will probably just buy a T6 or try out some wire arrays in the meantime.

     
  20. AE7F

    AE7F Ham Member QRZ Page

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