Dear Bryan, LF Group,
>Surely if antenna impedance is lo and amplifier higher then the antenna
>needs to be
>tapped down from the top and the amplifier final tapped "up" from there ?
>If moving the antenna tap detunes the the whole then a 'bit of coil at the
>bottom' needs
>adding or removing ?
More or less - but the point is that, for any particular antenna, coil
diameter and winding pitch, there are only one or sometimes 2 combinations
of TX and antenna tapping points that will work. Also, for quite a lot of
possible combinations of antenna, coil diameter and winding pitch, there is
NO combination of taps that will work.
>Mock it all up with infinitesimal power input , adust to matching /
>resonance.
>measure the inductances and build a Big Beefy copy.?
You could do this type of experiment, but it would be difficult to scale
everything to simultaneously maintain inductances, mutual inductance, Q and
stray capacitance at equivalent values to the full-size system, which would
be necessary to produce a valid result. Achieving this would be harder than
building the real thing! The spreadsheet calculations are an attempt to
theoretically predict the behaviour of the full-sized tuner, and so far seem
to give quite accurate results.
Cheers, Jim Moritz
73 de M0BMU
|
