more about QRP / Backpack portable Random Wires

Discussion in 'QRP Corner' started by KK4NSF, Dec 14, 2015.

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  1. W7CJD

    W7CJD Ham Member QRZ Page

  2. KB0TT

    KB0TT Premium Subscriber QRZ Page

    The thing is , John , that he LEARNED something in the process ...

    Good for him !

    JB
     
    AJ6KZ likes this.
  3. W7CJD

    W7CJD Ham Member QRZ Page

    Rather, I think this has been an exercize to demonstrate a "simple" wire antenna, only.

    I know I appreciate it.
     
  4. KK4NSF

    KK4NSF Ham Member QRZ Page

    maybe if you'd taken the time to use the right lengths, you'd have had better luck with them. Using your system, you either have to carry and string up a different wire for each band, and/or always have a poorly matched system on all but your primary band. No thanks. I'll stick with my single wire with a counterpoise layed on the ground.... and my 1.2 SWR across all of my bands.
     
  5. M3HJG

    M3HJG Ham Member QRZ Page

    Hi been reading this with interest I am going to buy some wire for backback and portable car/park qrp and give this ago have you had much success with this anything learned that or come across that you can help or advise me 73's
     
  6. KG7WGX

    KG7WGX XML Subscriber QRZ Page

    I have used a 35 ft end-fed with some success, but I think I like the SOTAbeams Bandhopper dipoles better.

    The 20/40m version is 66 ft long and the 20/30/40/80m version is 132 ft long. It is definitely harder to find room to set these up than the 35 ft end-fed, but they seem to work better. I try to set the 20 ft mast up near the picnic table so the supplied 33 ft coax reaches the transceiver. (20 ft of it goes up the mast to the feed point, so that leaves only 13 ft.)

    The term SOTAbeams uses is linked dipole, but I find myself thinking of the design as "alligator clip traps". ;)

    In order to do the 20m - 40m band change, I have to drop the support mast (or slack the support rope) and connect the clips, but as I do this only once per outing, I don't find it much of an inconvenience.

    [​IMG]
     

    Attached Files:

  7. KG7WGX

    KG7WGX XML Subscriber QRZ Page

    SOTAbeams sells a linked dipole antenna kit for around $19, which is a considerable savings over the factory assembled model -

    https://www.sotabeams.co.uk/linked-dipole-portable-hf-antenna-kit/

    and there is a nifty calculator for determining the lengths of the wires -

    https://www.sotamaps.org/extras

    In addition to winding the balun and making all the connections, you need to find a 20 ft telescopic mast, but these can be found on eBay for $25 or so in fiberglass. The carbon-fiber ones can get expensive. And for the sites which have convenient trees, you can leave the mast at home.
     
  8. KA0USE

    KA0USE Ham Member QRZ Page

    i LIKE this whole thread!
     
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  9. AJ6KZ

    AJ6KZ XML Subscriber QRZ Page

    I am new to portable QRP but I can tell you that the SOTABeams Band Hopper is pretty neat. I used it with my KX2 to reach a friend of mine on the West Coast while I was in Hawaii (CW mode, of course). Combined with the Tactical Mini mast it's pretty fast to set up, and of course you don't need to have a tuner. On a side note, I removed the top section of that mast as it was just too wobbly for the way I was setting up.
     
  10. N8AFT

    N8AFT Ham Member QRZ Page

    Glad you did this legwork that took all day to accomplish...
    I've seen these same types of tests ran by European antenna builders, HyEndFed comes to mind... Check their test proceedure/results.
    How about looking at the current running through the driven element as well as the counterpoise wire???
    What about the value of a field strength meter reading?
    Not to be critical but those are valid measurements for any antenna builder to consider and not just the SWR. That's my only point...
    Yes, the 124.5 and 53 foot lengths are good information...
    I think with all the test data available these days that the science is pretty much cinched and we can erect a FB working wire the first time out...
    My first wires were struggles but I learned a lot too...
     
    Last edited: Feb 27, 2020
    KA0USE and KK4NSF like this.

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