Adjust-A-Loop

Discussion in 'Amateur Radio News' started by Guest, Jan 15, 2001.

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  1. Guest

    Guest Guest

    Charlie, VE7BOC/W6 (HA5CMG) writes "If you are using a fixed 80 M or 40 M coil on your mobile antenna then you can make it TUNABLE!!!





    Buy several 1/16" X 3' long stainless steel welding rods.


    Remove the existing small ball from the whip.
    Make a new ball about 5/8" or more in diameter. Drill a hole the same diameter as the top of the whip. Force it on or better yet use a small setscrew to secure it to the whip.


    Drill a 1/16" dia hole about 30 degree in relation the the whip right tru in this hole push the SS welding rod tru so now you have about 15 to 20" hanging down from the ball.


    Grip the whip and the SS rod together and wind the SS rod 7 or more times tightly on the whip about 6-8" below the ball. On top of the ball you should keep 6-8" lenght of a "pig tail" that you will use as adjusting the loop diameter inch by inch.



    Now you have an ADJUST-A-Loop Top Hat on your fixed mobile antenna.



    You will notice that the coil is now "longer" that it was. This is due to the Capacity hat you just installed. Either short out the exess turns or remove it.


    You have increased the Radiation Efficiency of your bugcatcher or other fixed coil center loaded antenna!!!



    Set the Loop size to the midle of the band where you want to work.



    BY ADJUSTING THE PIGTAIL LENGHT IN AND OUT OF THE BALL AN INCH THE FREQUENCY WILL CHANGE ON 80 Meter ABOUT 10 KC.

    Pictures available for the asking.



    73's Charlie

    www.qth.com/stealthantennas"
     
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