RE: flat secondary

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "David Thomson by way of Terry Fritz <twftesla-at-qwest-dot-net>" <dave-at-volantis-dot-org>

Hi Marc,

My guess is the inductance and self-capacitance in this coil is going to
preclude it from resonating near the quarter wave frequency.  I would
suggest measuring the frequency across the center terminal and outer lead as
I mentioned in a previous post.  Then solve capacitance from known frequency
and inductance.  Use that capacitance as your primary capacitor.  I have
found the best performance with the capacitance split between two caps, one
on each end of the primary coil.  I would use coax cable for the primary and
wind it in a flat spiral starting from at least 1/2" beyond the
circumference of the secondary.  For this size of diameter/awg ratio I would
expect four to eight turns will be necessary to resonate the coil,
especially with the 360VA transformer.  You will probably need a very narrow
gap on the spark gap.

Voltage rating on the primary capacitor(s) can be less than 12KV.  I have
run 10KV rated caps on my 15KV 60mA NST with no indication of heat at all.

Do try the "normal stuff", first.  I would like to know if you can get it
resonate near quarter wave.

Dave