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Thread: off centre fed wire antenna

  1. #1

    off centre fed wire antenna

    hi!

    I want to build a "long wire" type of antenna - really an off-centre fed antenna - 34m one side 7 m the other (approx). According to MMANA this should give me a feeding point of 180 ohms and a very adequate gain and direction of 14MHz and 7MHz. The wire to be used is 2.54mm insulated household wire (#10 wire).

    Questions:
    1. I am thinking of building a home-built ladder line for this antenna made of the same wire (#10 wire - 2.54mm = 1/10th of an inch diameter copper wire) about a pencil thickness apart (roughly 1/4") which I think should give me 180 ohms or near that. Can somebody confirm this please?

    2. I am not sure which kind of toroid to use. If I superglue 2xFT240-52 toroids together and wind 5 turns primary and 18 turns secondary (to get the 50:180 transformer needed) on this superglued toroid core, using the same #10 wire, how much wattage roughly will this transformer withstand?

    thanks to all who will answer and best 73s from
    Joe, 9H5JO

  2. #2
    Administrator N8YX's Avatar
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    Joe,

    Amidon and the other toroid core manufacturers should have data sheets for their products which list power saturation curves as a function of frequency. From this it should be easy to determine transformer heating for a given frequency, winding construction and applied power level. There should also be a "do not exceed" value noted as well.

    As far as ladder line spacing goes, I'd use EzNEC or a similar antenna modeling program. There may be an online version that you can use.
    "Everyone wants to be an AM Gangsta until it's time to start doing AM Gangsta shit."

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