RE: Question about Primary Inner Diameter

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

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

I think you may be cutting the pri-sec clearance a little close.  I have
a 6.25" secondary and my primary ID is 8.25", and that's *usually*
enough clearance when the primary is at the same level as the first
secondary turn.  I don't think that adding NST's affects clearance
requirements.  But a bigger problem I see is with the limits to how
close you can get your secondary to your primary.  You may find that you
want to get closer than 1.25" above the primary to get good coupling.  I
also once tried building my primary below a lexan sheet, but found that
I couldn't get the coupling high enough.

Regards, Gary Lau
MA, USA




Original poster: "Bill Vanyo by way of Terry Fritz <twftesla-at-qwest-dot-net>"
<vanyo-at-echoes-dot-net>

I just built a new primary for my new (first) coil.  I'll explain why
below.

Due to the way I constructed it, I couldn't precisely control the inner
diameter.  Now I have a secondary with 6 5/8" diameter, and the primary
inner diameter is about  8 1/8" (whereas it was previously 9.5").  Will
this be work?  I'm using three 15/60's as power, and want to add a
fourth (if that's relevant).

Will it help if I raise the secondary somewhat?  Structurally, what
works best (easiest) is for the lowest turn of the secondary to be about
1.25" above the top of the primary.  I could lower it a bit.  I will
also have a plexiglass sheet over the primary, below the level of the
bottom turn on the secondary (again, if that's relevant).

	Thanks again,
	Bill Vanyo
<snip>