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Below left: My present day antenna farm consists of a Rohn
FK2558 foldover tower using a 4-point guying system. Atop the tower is a Hy-Gain TH3MKII
tribander that I have had since 1966. It has been rebuilt 3 times over 40 years and still
delivers excellent performance. It is rotated by a Hy-Gain Ham IV rotator. Also mounted on
the tower are full wave loops for 40 and 80 meters fed thru 75 ohm 1/4 wave matching
transformers along with a inverted-L for 160 meters fed thru a motorized base matching
capacitor.
Below right: Antenna switching is
carried out by the unit pictured below. I built this one from an article in QST. It
effectively grounds all antenna's and control cables when the power is removed from the
unit. It uses heavy duty Potter& Brumfield PRD-11DYO-24 wide spaced contact relay's.
Everything is housed in a Hoffman waterproof enclosure. All cables entering the enclosure
are routed thru bulkhead connectors that have sealed gaskets to prevent moisture from
entering. This unit is used to select either the 75 or 40 meter Delta loop's, the 160
meter Inverted L or the tribander. I would highly recommend this switchbox to anyone
needing a heavy duty unit. It was engineered and constructed by W5AN and the article
appeared in QST in August of 1997. See the article
here. This photo was taken prior to completion. |