From:
Fred Hopengarten, K1VR
Six Willarch Road * Lincoln, MA 01773-5105 * 617/259-0088
e-mail: k1vr@juno.com
Big antennas, high in the sky, are better than small ones, low.
On Mon, 30 Dec 1996 20:38:46 -0500 thomas@cybrzn.com writes:
>Gentleman:
>I am in final stages of putting together 1/4 wave vertical for 80M,
>with
>about 70 on-ground radials. The radiator will consist of aluminum
>tubing, tapering from 2-3/8" to 1-1/4" o.d.
>Can I lay the vertical on a pair of sawhorses and employ a dip
>oscillator to find the resonant length? Or, how about standing it up
>and
>tieing it off about 2 feet away from my tower so I can climb up and
>trim
>off the top end (would not be using any radials for this procedure),
>or
>would the proximity of the tower cause a shift in the resonant
>frequency. Will adding the radials later cause it to resonate on a
>different frequency? Would prefer to do the trimming at the top end,
>as
>I will have the feedpoint hardware, etc already in place at the base.
>What say, antenna gurus?
>Thanks in advance for your input.
>
>Tom K0SN
>Porterfield, Wi.
K1VR: The ColAtchCo system (by W1CF and W1FC) solved the tuning problem
by making a swivel at the bottom of the vertical so that it could be
lowered and raised easily. Frequency was then adjusted by the use of a
small "top hat" of three wires near the top which go out to insulators
and continue as guy wires (using dacron rope). Just trim the top hat and
don't screw around with a system of metal taper which works
mechanically. This is the system in use at W1FC, W1FV, K1VR, K1MEM and
others.
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