re: 3/4 wavelength secondaries
I have guess to make based on some calcs I did over the
weekend. I think the best you can do without top C is to approach
a 1/2 wave coil. My findings were exactly yours regarding the 3/4
wavelength job. It is clear one can reduce the fractional wavelength
to very low values with arbitrarily large top C (e.g. 1/8 or less).
> In any event I do not believe a 1/4 or 3/4 wave coil can be wound in any
> "reasonable" configuration. In fact the resonant frequency of 1/4 wave
> coils is always about 40% higher than the 1/4 wave wire length and a
> toroid must be used to bring in the frequency even taking into account
> the increase in cself due to ionization. The resonant frequency of a 3/4
> wave coil is always lower than the 3/4 wave wire length so the 3/4 wave
> coil cannot be tuned at all.