Re: Preliminary design... Any suggestions?

At 06:10 PM 08/25/1999 -0600, Tesla List wrote:

>Original Poster: "Albert Race" <race-at-dgms-dot-com> 
>Ok, guy's... I'm sending out my preliminary design for you with experience
>to review and make professional comments on.
>This is my first "bigger" coil. I have only fooled around with Flyback
>derived coils before, so I'm really excited.
>Here goes:
>Source EMF:120VRMS 60Hz (USA)
>Input Transformer for primary: 120VRMS to 15,000VRMS 60mA NST>

What's the actual output voltage rating on your NST?

>Secondary stuff:
>       Diameter : 6 inches
>       Length: 27 inches
>       Ratio: 4.5
>      Turns: 950
>       wire: 22AWG
>       Secondary Coil Length: 23.37 in
>       Winding Ratio: 3.895
>       Secondary winding length: 1492 feet
>       Weight: 7.566 lbs

Why quibble over a fraction, make it 24 inches winding length.

>       Outer Diameter: 18 inches
>       Cross sectional diameter: 4 Inches
>       Torroid Capacitance: 19.61pF

Also try a thicker toroid. These 6" coils love big toploads.

>       Total capacitance of secondary: 30.43pF
>       Calculated secondary resonant frequency: 163.442 Khz
>Primary:(Flat Spiral)
>       Primary coil ID: 10 inches
>       Primary Wire Diameter: .375 inches
>       Spacing: .400 inches
>       Number of turns: 5.4

You might consider building a larger primary and adding up 
to 16 turns. That way, you have designed room for expansion
in case you want to go to a larger cap or topload in the future,
not to mention if you come across another NST you want to
parallel with your present one. You can always tap in at lower 
turns for your present specs, and move outwards on the turns 
when you upgrade components. 

It isn't clear to me if you're using wire or copper tubing for the
primary. If it's tubing, I think your spacing is too wide. 

With my 6" coil, with a flat primary of 16 turns of 1/4" tubing 
at 1/4" spacing between the turns, using a 900VA NST 15/60
with just one .01 mfd cap, a 11 gap static gap unit and a 
20 x 6 topload, I average 40" consistent streamers.