John,
My original plan was to use 16 or 14awg wire for that reason of
keeping the
coil short. The 12awg wire i have is a special type which will give
a primary
winding height of only 2.8". The 14awg wire would give the same
height.
But the 16 gauge wire I have has thinner insulation and would give a
much
shorter coil. I agree with what you're saying and I'm going to
switch to
16awg for the primary. That will increase the primary inductance,
so maybe
I can use fewer turns too. That will let me put the grid coil on
top of
the primary. I've built coils both ways; grid coil on top, grid
coil below.
I do have an air variable which I plan to use to find the proper
tune point,
then I'll replace it with a fixed cap. Actually I have an air
variable which
is in oil to withstand higher voltage and give a higher capacitance.
I've used the 4-125A tubes in previous coils, and also a 4-250A and
a 4-400A. The last tube was defective however and gave weak sparks.
I have a good selection of mica caps.
Appearance-wise, I prefer a shorter primary coil also, so that's
another
reason for me to use the 16awg wire. It would be interesting to try
magnet wire for the primary coil. I have some 14gauge magnet wire.
I also have some litz wire, but I forget the gauge. I seem to
remember
hearing that litz wire is particularly helpful above 500kHz if I
remember
correc
tly.
Thanks again,
John
-SNIP--------------------SNIP