Saturday, December 14, 2013

Inverted L for 40/80m

I just got done with my 40/80 inverted L. I made a 40 meter trap out of a T80-2 toroid with 46 turns in parallel with a 39pF 500V silver mica capactitor. My method of testing the resonance point involves using a binocular core balun with 2 turns wound for the primary and 5 turns wound on the secondary. The secondary is looped through the trap core twice and loosely. I had to adjust the turns on the toroid to achieve a 7040kHz resonance. Once that was achieved I put super glue on the windings to lock them into place. The center insulator is some plastic rod that just happen to fit down the center of the finished coil. I drilled two through holes to accommodate the antenna wire to slip through both and just tied a knot in the wire.

The vertical portion of the antenna is about 30.5 feet. The trap is placed at approximately the 31.5 foot level off at a 90° angle to form the flat portion of the inverted L. My pole supports the wire close to the trap. 80 meters is brought into resonance by starting with a 25 foot piece of wire. I had to trim quite a bit off before it was dead on at 3560kHz. It seems like 2 feet came off.

Myron WVØH
Printed on Recycled Data

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