Test: Bigger Secondary gives Bigger Sparks


Recently I posted my results from a small TC with a 3" by 12" 
secondary which gave 14" sparks using a 7.5kV, 30ma NST,
120bps sync rotary gap, 13.3nF cap, and 3" x 10" toroid.   The
#12 wire primary was tapped at 6.5 turns.  A nice mini-TC.

I removed the small secondary and installed a larger 4.2" by 23" 
secondary also wound with #28 wire.  I retuned at 18 turns on
the primary as needed.  All else remained the same, but the
spark increased to 22" for a 57% increase.

Other things that automatically changed; greater primary inductance
and surge impedance, greater secondary inductance and Cself,
lower frequency, no racing sparks.  It is not known how much each
factor contributes to the 57% spark length improvement.  

It is intriquing to consider that perhaps the spark lengths of many
other TC's could be easily but greatly improved, simply by installing
a larger secondary with greater inductance, and retuning as needed.

John Freau