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Single turn vs Double Turns

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  • oh6bi
    Hello all. I built the rockloop based on dl1gsj article. (http://www.qsl.net/dl1gsj/html/rockloop.html) Thanks Joachim. The condensator i used is butterfly
    Message 1 of 2 , Sep 3, 2008
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      Hello all.

      I built the rockloop based on dl1gsj article.
      (http://www.qsl.net/dl1gsj/html/rockloop.html)
      Thanks Joachim.

      The condensator i used is butterfly 2x40 pF, toroid is made by
      Philips, I dont know the specs. I used it like in series - 3 to 20pF,
      and I was able to run even 100 Watts , no sparking in cap and no
      heating in the toroid. First test was sidelengths abt 80 cm, loop
      was working nicely from 18 MHz to 29 MHz. I made some local QSOs at
      10m with good reports.

      But my favourite band is 14 MHz, so I put some more wire to the loop
      sides abt 90 cm and got the resonance at 20m. Same time I loost 28
      MHz.

      I made some calculations: with the same length of loop wire I could
      make two turns and reach lower resonance freq. to reach lower band
      with same material. Goeing to test it in the evening.

      My question is : what happens to system when using two turns, shall
      the efficiency drop down compared to one turn loop ?

      73s de rami, oh6bi
    • Chris Trask
      ... Yes, the efficiency will decrease as the number of turns increases. For 20M, you can use a 64cm diameter loop and get good efficiency. The larger the
      Message 2 of 2 , Sep 4, 2008
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        >
        >But my favourite band is 14 MHz, so I put some more wire to the loop
        >sides abt 90 cm and got the resonance at 20m. Same time I loost 28
        >MHz.
        >
        >I made some calculations: with the same length of loop wire I could
        >make two turns and reach lower resonance freq. to reach lower band
        >with same material. Goeing to test it in the evening.
        >
        >My question is : what happens to system when using two turns, shall
        >the efficiency drop down compared to one turn loop ?
        >
        >73s de rami, oh6bi
        >

        Yes, the efficiency will decrease as the number of turns increases. For 20M, you can use a 64cm diameter loop and get good efficiency. The larger the diameter of the conductor, the better the efficiency.




        Chris

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