Re: Primary Coil Under Secondary Coil -Reply


If the primary is placed at the midpoint, the coil sparks from both
ends if neither end of the secondary is grounded...so it becomes a half
wave coil.  If one end is left grounded, there's a high likelilhood of 
flashover from primary to secondary.  However, in tube coils, it is
possible to raise the primary a lot relative to the secondary, and it
has the effect of changing the tuning.  In fact this method can
be used to tune a tube coil that isn't tuned correctly.  Just raise the
primary until the spark is strong.  I haven't really explored the 
phenomenon, in fact it was a friend of mine who used the technique,
and told me about it quite a few years ago.

John Freau"

	You'd do better adjusting the tuning as you vary the coupling from a
low value to a high one.  With the CW excitation you want to maximize
the power in the discharge, and this procedure will produce it.  Similar
to coupling any oscillator or power amplifier to an antenna.  There is a
condition of optimum and coupling which gives the desired oscillator or
amplifier loading.