The problem is always cost, but adding one additional short
can make a whale of a difference! The easiest trick is to
not operate near frequencies when the coil has an internal
resonance in the unused turns.
As the coil is collapsed and operating frequency increased,
the resonance moves lower. At some point they might cross.
This is why multiband tank circuits have pick-up-and-hold
switches, and wide operating range amps or tuners often have
problems with tank arcs when builders use roller inductors
or switch arcs when they unwisely let unused taps float.
73, Tom W8JI
>If the portion of the coil inside the tube isn't used,
couldn't you just
> add extra finger stock contacts at regular intervals along
> length of the tube to short out the unused turns?
See: http://www.mscomputer.com for "Self Supporting Towers", "Wireless Weather
Stations", and lot's more. Call Toll Free, 1-800-333-9041 with any questions
and ask for Sherman, W2FLA.
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