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Questions for the loop experts for MW Dxing

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  • neilbell99
    1. What is the main factor in determining loop nulling ability? Size of the loop, sharpness of tuning (Q), spacing of the wires, shape (Round or square),
    Message 1 of 2 , Jun 29, 2013
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      1. What is the main factor in determining loop nulling ability? Size of the loop, sharpness of tuning (Q), spacing of the wires, shape (Round or square), number of turns, etc.

      2. Is there a significant difference in nulling effectiveness between an air-core loop and a ferrite bar antenna (like the twin-coil sold by Crane)

      I want to buy (or make) a loop with excellent directivity, maximum size about 16 inches. Tuning capacitor of pretty good quality.

      My receiver is fairly selective but some amplification would help a lot for the distant low power Graveyard stations.

      Obviously something like the famous KIWA loop would be nice, but they are very hard to find and quite expensive.

      Advice, comments or suggestions greatly appreciated. Currently I use a cheap Kaito an-100 loop directly connected to my Yaesu receiver.

      Neil BEll, KJ6FBA
    • roberts50000
      The National Radio Club has some good handbooks on building a good receiving loop for MW DXing. My experience has been for best nulls you want a BALANCED loop.
      Message 2 of 2 , Jul 1, 2013
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        The National Radio Club has some good handbooks on building a
        good receiving loop for MW DXing.

        My experience has been for best nulls you want a BALANCED loop.
        That means one side of the loop is not grounded. Both ends of the loop
        are above ground with a center-tap, usually used with a balanced preamp.

        Tuning capacitor should be mostly symmetrical, not one side connected
        to a big metal frame.

        Using one of the newer one-turn broadband active loops solves many
        problems. No tuning capacitor is used so the loop is well balanced
        electrically.
        Single-turn broadband loops have excellent nulls. No cumbersome remote
        tuning capacitor needed if mounted outdoors.

        73 - Todd WD4NGG


        In a message dated 6/30/2013 4:38:25 P.M. Eastern Daylight Time,
        neil.neilbell@... writes:

        1. What is the main factor in determining loop nulling ability? Size of the
        loop, sharpness of tuning (Q), spacing of the wires, shape (Round or
        square), number of turns, etc.

        2. Is there a significant difference in nulling effectiveness between an
        air-core loop and a ferrite bar antenna (like the twin-coil sold by Crane)

        I want to buy (or make) a loop with excellent directivity, maximum size
        about 16 inches. Tuning capacitor of pretty good quality.
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