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Re: k cravens coil

> Now to the group in general:  I'm seriously thinkin' about a "real" cap.
> too. Maybe someone could tell me if the 20kv .025uf condenser prod. cap will
> work with my stuff...i.e...
>  9kv -at- .240ma neons, (or 12kv -at- .030ma can get more if needed)
>  5.25" dia.X 36" sec.   (also have 8" X 24.5" acrylic)
>  primary .25" coppr saucer 12 turns -at- 3/8" spacing (also have one w/3/8" cu)
> 
>  Can I use about any value cap. and tune at the primary? Will a 9kv trans.
> work with a 20kv rated cap? I'm learnin' stuff, but still a rank amateur :)
> 
> Oh yeah, usin' stationary spark gap (7 cu. pipes 6 gaps) and a good rf grnd.

Yes, you can use these 20 KV AC RMS CP caps with your system.  The voltage rating
is the maximum working voltage.  So, you don't want to use above a 20 KV
transformer.  Anything below that is AOK.

Will it work with 9 KV -at- 240 mA?  Sure.  Plenty of current at that voltage.  At 9 Kv,
you would only need about half the current to match the cap.  So, 240 mA will be just
fine.  15 KV at 30 mA isn't enough current.  You will need about 180 mA at 15 KV to
properly match the cap.

As you suggest, you can use any value capacitor and tune with the primary windings,
but only within reason.  For instance, you wouldn't want a tiny capacitor and a 50
turn primary, or vice-versa.  You need to keep this reasonable.  What is reasonable?
You be the judge.  Just use common sense here.  In general, it is preferred to
keep the primary winding diameter approximately the same as the secondary winding
height.  This is to optimize coupling.  But this is just a rule of thumb.  I
personally like my secondary's diameter between 50% and 100% the length of the
secondary winding.  So while you can use any value of the capacitor, it relationship
must be kept within reason for many reasons, like Q factor and coupling coefficient
adjustment.

If you are interested in a commercial cap, let me know.

Scott Myers