RE: Primary spacing question

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: "Lau, Gary" <Gary.Lau@xxxxxx>

Two issues here - sufficient clearance to prevent pri to sec arcing, and
coupling.

For my coil with a 15kV NST (current doesn't factor in), a 1 inch
horizontal clearance between the lowermost sec turn and the innermost
pri turn was adequate, assuming that there are no sharp projections or
bend radii that might precipitate corona.  In theory, a 7.5kV NST should
require just half of that, but that just seems to be pushing your luck,
and there's no reason to be so close.

For coupling, I've found that having the lowermost sec turn between 0
and 0.5" above the plane of a flat spiral primary gives best coupling
without racing arcs, but be prepared to adjust and determine this
yourself, as this will vary with differing primary geometries.

Regards, Gary Lau
MA, USA

> Original poster: "bmcpeak" <bmcpeak33@xxxxxxxxxxx>
>
> Hello Group,
> I am working on the construction of my two coils and would like to
> ask the group their opinion on the spacing of the inner turn of the
> primary coil to the secondary.
>
> Coil #1... 6 inch o.d. form, 15000/60 m.a. NST,  LTR MMC cap .0150 uF.
>
> Coil #2... 3 inch o.d. form, 7500/60 m.a. NST,  LTR MMC cap .0300 uF.
>
> T.I.A.!!!
> Brad McPeak
>