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It's a bit late for Christmas puzzles but try this
one:
Circuit A is the usual antenna tuning cct for a short
highly reactive whip. It has the advantage that the antenna tuning inductor can
be a long way away from the PA.
Circuit B has been widely used for HF walkie-talkies
using a short whip. Only one coil is needed because the end of the antenna can
be brought right onto the PA board.
Puzzle:
The tuning coil in A tunes very sharply; you really need
a continuously-variable inductor.
That in B tunes quite flatly and you only need a few
fixed taps.
Why?
Incidentally, are they really the same
circuit?
Happy New Year!!!
Walter G3JKV.
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