Re: which coilform parameters best?

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

Original poster: "Barton B. Anderson by way of Terry Fritz <twftesla-at-qwest-dot-net>" <tesla123-at-pacbell-dot-net>

Hi John,

Tesla list wrote:

> Original poster: "John Friesenhahn by way of Terry Fritz
<twftesla-at-qwest-dot-net>" <johnfrie-at-swbell-dot-net>
>
> This will be my first attemp at a "larger" coil and can't seem to make
> up my mind as to which coilform parameter might be best.  I have to work
> around my .1uf 50kv oil pulse cap, 3600 sync rotory, and 5kva pole pig
> (maybe two for 14.4kv). As I understand it, I will need 1900-2000 ft. of
> wire, 800-1000 wraps -at- 3:1 coilform ratio.  If I use a 10in dia form and
> 18ga coated wire, I would get around 800 wraps -at- around 2000 ft. of wire
> and 33 in. tall winding.  I could also use an 8 in. dia form, 20ga wire,
> 820 wraps, 2000 ft. -at- 28 in .tall winding.  I would be leaning toward
> the 10in. dia but I just don't have the experience to decide which.  Any
> ideas or better suggestions?  Thanks, John.

Not sure why you are figuring on around 2000 ft of wire, unless your 3:1
h/d ratio just happens to work
out around there. Assuming you did build a 10 x 30, you end up somwhere
around 700 turns and end up with
a primary which has 5 turns if using a toroid of say 9 x 30. If you do
stick with a 3:1 ratio, the top
of the coil will only be 30" away from the primary if flat, and closer if
helical or conical.
Considering arc lengths you can expect using a 5 or 10 kva pig, you might
want to consider something
nearer to 4 or 5:1 h/d ratio. This would add turns to both coils and
increase the distance between the
top terminal and primary. Also, I would go for a 10kva pig. The 5kva will
be fine at 120 bps, but
because of the large cap size and slow charge time, I think you would end
up happier with a 10kva pig in
the long run.

Take care,
Bart