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Re: [loopantennas] da loop

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  • fraz1
    Scott, I don t think you ll see a any significant impact form the metal poles; probably none at all. The homebrew ladder line may provide a broader SWR than
    Message 1 of 3 , May 11, 2008
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      Scott,

      I don't think you'll see a any significant impact form the metal poles; probably none at all.

      The homebrew ladder line "may" provide a broader SWR than commercial 450 ohm line. But, given you're balanced tuner, I'd opt for the 450 ohm commercial window line. W7FG offers "real" open line around 600 ohms for a good price.

      Put it up, and have fun.

      73 John K4NP www.k4np.net
      ----- Original Message -----
      From: ka7nwq
      To: loopantennas@yahoogroups.com
      Sent: Sunday, May 11, 2008 12:35 PM
      Subject: [loopantennas] da loop


      Thanks to all of you for your previous replys on my questions regarding
      the big loop antenna. Things have changed and I have been blessed with
      opportunity to fulfill 2 of my dreams. #1 is being able to have enough
      land at my disposal to put up any antenna that I desire. The close 2nd
      is dog training. Anyway, I want to be able to have a 160 meter loop
      and feed it with ladder line. My thought is to support the loop on all
      4 sides with 50 feet of cyclone fence posts, stuck together and guyed
      with dacron rope. I have plenty of room for this monster, but my
      questions are.......what will my supports do to the performance of the
      antenna (should I use the fence post approach, wood or pvc around the
      fence post as an insulator) and should I feed this with 450 ohm or
      homemade open wire line. If homemade, then what should the spaceing
      be? My tuner is the MFJ 974HB going to a Icom PRO 3 running 100 watts
      for now. As far as the feed line length goes, well, it can be as far
      away from the house as it needs. Thanks again for your reply

      Scott
      KA7NWQ






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    • Jim Dunstan
      ... In my opinion and experience there is no detectable difference in performance between those antennas supported by metal or non metal supports. The general
      Message 2 of 3 , May 11, 2008
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        At 05:35 PM 5/11/2008 +0000, you wrote:

        >Thanks to all of you for your previous replys on my questions regarding
        >the big loop antenna. Things have changed and I have been blessed with
        >opportunity to fulfill 2 of my dreams. #1 is being able to have enough
        >land at my disposal to put up any antenna that I desire. The close 2nd
        >is dog training. Anyway, I want to be able to have a 160 meter loop
        >and feed it with ladder line. My thought is to support the loop on all
        >4 sides with 50 feet of cyclone fence posts, stuck together and guyed
        >with dacron rope. I have plenty of room for this monster, but my
        >questions are.......what will my supports do to the performance of the
        >antenna (should I use the fence post approach, wood or pvc around the
        >fence post as an insulator) and should I feed this with 450 ohm or
        >homemade open wire line. If homemade, then what should the spaceing
        >be? My tuner is the MFJ 974HB going to a Icom PRO 3 running 100 watts
        >for now. As far as the feed line length goes, well, it can be as far
        >away from the house as it needs. Thanks again for your reply
        >
        >Scott
        >KA7NWQ


        In my opinion and experience there is no detectable difference in
        performance between those antennas supported by metal or non metal
        supports. The general rule for HF antennas is "as high and as in the clear
        as possible". The difference between 'most' commercial balanced feed-line
        and home made balanced feed line is its performance during wet weather. In
        almost all cases an antenna fed with balanced feed line will be carrying
        power with some level of SWR. The result is that the antenna/feed-line
        system is 'tuned', and water on the feed line de-tunes the system. For
        amateur purposes I have not found this to be a problem ... a small 'tweek'
        of the antenna tuner knob and it is 're-tuned' with no detectable
        difference in performance.

        The reason most commercial balanced line is susceptible to wet-weather
        de-tuning is due to the use of the molded plastic insulation used for
        structure/support .... which makes it much easier to use. Non-susceptible
        line uses a more delicate construction that represents a minimum of
        material between the parallel wires. If you are construction a high power
        remote station this is what you want ... e.g. tune it and forget it hi hi.

        Jim, VE3CI
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