K7ITM wrote:
Huh? You wrote, "if tight winding results in a lower Q/other
effects, why space the windings for air-core, crystal radio coils,
period?" Do you not want a higher Q? Generally, people try for the
highest unloaded Q they can get, under some set of constraints.

Sorry, I made a typo. Rather, why do people tight-wrap coils, period?
Just ease of construction?

Close spacing lowers the Q mainly because the current in the wire is no
longer radially symmetrical, if you look at a cross-section of the
(round) wire. That raises the RF resistance of the wire. For decent
(low-loss) form material, it's mainly the RF resistance of the wire
that determines the loss and therefore the Q. Generally, highest Q for
a given diameter and length is obtained by spacing the wire about two
wire diameters, center to center, at least for high frequency work. If
you want to use Litz wire, there's an optimum stranding...more, finer
strands are not necessarily better as you get to either lower or higher
frequencies. You should be able to find info on that, if you do some
searching.
SNIP
Cheers,
Tom

Thanks for the information! Is there an advantage to wrapping cylinder
coils as opposed to spider or torroid, other than ease of construction?
I'm debating which one I'd likely get the best result with... I'll
probably make both to try it out, but I'd like to know which one would
'probably' work best.

Thanks again,
Dave