RE: Another Primary Coil question

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

Original poster: "Lau, Gary by way of Terry Fritz <twftesla-at-qwest-dot-net>" <Gary.Lau-at-hp-dot-com>

There are two separate issues here.

There is the largely horizontal clearance between the innermost primary
turn and the secondary, necessary to prevent arcing between the two.  This
distance is determined by the power supply voltage.  With a 15kV NST, I've
gotten away with as close as 0.75" clearance, but I would recommend a full
inch.

Then there is the vertical spacing between the plane of the primary and the
lowermost secondary turn, establishing the pri-sec coupling.  The things
that determine what is optimal are not fully understood, just that the
coupling should be as high (pri & sec close together) as possible without
racing arcs developing along the secondary.  I have found that positioning
the secondary's lowermost turn just above the plane of the primary to be
best, but your coil is likely to be different and you should plan to have
at least 1-2" adjustability above and below the plane of the primary.

Regards, Gary Lau
MA, USA


Original poster: "Daniel McCauley by way of Terry Fritz
<twftesla-at-qwest-dot-net>" <dhmccauley-at-spacecatlighting-dot-com>


Just one more quick question regarding flat-pancake primary coils:

How close should i start my primary coil from the secondary??  What
determines this.
Thanks again.

Dan