Re: Do these numbers look right?

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

Original poster: FutureT-at-aol-dot-com 

In a message dated 2/16/04 7:18:24 PM Eastern Standard Time, 
tesla-at-pupman-dot-com writes:

>NST = 12,000v, 30ma, 60hz
>Secondary = #22 wire, 20" long, 4" diameter, 765 turns-at-97%
>Primary = flat spiral, I.D. = 6", 15 turns, .25" pipe, .25" spacing,
>width=7.25"
>Capacitor = .007uf
>Toroid = Dmin= 4", Dmaj= 24"
>
>The spreadsheet says secondary res F = 257kh, primary res F = 221khz.
>
>My concern is if I use any larger cap, I can't get the prim/sec parameters
>to match good enough.


JC,

The final tuning is always done by trial and error.  If you use a larger
cap, you'll need to tap in fewer primary turns.  By moving the tap,
the proper tune point can be found by trial and error test runs.
You are correct to mention a larger cap since it's traditional now-a-
days to use an LTR cap which means it's about twice the value
you mentioned or 0.14uF for use with a static gap.  If you use a
sync rotary gap, then an even larger cap can be used.

      Also, I don't have any material for a toroid here

>that I can look at so I assume 4" almunin flex hose but I don't know if 24"
>is realistic.


Well I used 4" x 17" for my initial work, then I switched to a 5" x 20"
toroid.  Yes, 4" x 24" will work.  Now I use a 4" x 13" spun toroid.

     Lastly, the primary requires 53' of copper tubing. I am not

>sure where to buy such a long length. I have seen only 25' at Home Depot.


You can easily connect two pieces of tubing together to get the length.
To connect them, just make the ends flat and smooth and clean, then
force a piece of tinned brass rod into the tubing and solder the pieces
together.  What you can do for initial tests is to use some scrap
insulated 12awg wire to make a primary.  Then you can find the
correct tap point.  Then you can re-make the primary using nice
pretty tubing if desired.

I think I already gave you my website URL the other day for my
12/30 NST TT-42 TC.  Who knows... I can't remember anymore....
well I'll give it again.

       http://hometown.aol-dot-com/futuret/page3.html

Cheers and good coiling,
John


>Thanks.
>JC
>