Re: primary INSIDE of secondary?

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

Original poster: "David Speck by way of Terry Fritz <teslalist-at-qwest-dot-net>" <dave-at-davidspeckmd-dot-org>

I wonder if this would apply to VTTCs as well.  An inside primary would 
allow for a lower primary inductance, and higher operating frequency.  I 
wonder what ratio of primary to secondary diameter would work best for my 
4" Diameter secondary.  I would put the grid coil outside the secondary at 
about 1" away.  ANy thoughts?

Dave

Tesla list wrote:

>Original poster: "Dr. Resonance by way of Terry Fritz 
><teslalist-at-qwest-dot-net>" <resonance-at-jvlnet-dot-com>
>
>This does work.  Greg Leyh's very large coil used this design to produce
>sparks in excess of 50 ft.
>
>In most small coils the primary resides approx 2 1/2 to 3 inches below sec.
>to obtain proper coupling so you could wind your pri. on the exterior of a
>Glyptal coated PVC tube which would allow you to raise and lower the pri for
>best coeff. of coupling.  Up in the base of the sec. approx 7 inches up
>silicone a 1/4 thick acrylic disk in place to help prevent interior
>flashovers.
>
>Keep your spark gap set tight and the variac down to under 30% when doing
>your primary tap tuning.  Then, later, replace the scrap wire primary with a
>high quality well insulated wire and no taps the could arc over.