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Re: TT-42 update

In a message dated 00-02-28 08:15:42 EST, you write:

<< Hey John,
 
> Glad to hear your getting your portable coil running well. As I've known
> for quite some time now, you have an excellent system in place to spin your
> toroids. Just how large of a toroid can you spin? I've avoided spun toroids
> mainly because I need to be in the 50pF range on my coil (is this too much
> for your spinning system?).

Hi Bart,

I offer two sizes; a 1.5" by 6" toroid, and a 4" by 13" toroid.  I  also
make a 3.5" by 11.5" pseudotoroid which is flat on the top and
bottom (oblate spheroid shape).  I have no plans to make larger toroids 
at this time.

> Refering to your arc length; Your running 120
> bps on a 12/30 NST? So your beyond the input watts equation. 

NST's can draw double or more their rated power in a sync gap system,
and when more than 120 volts is supplied (I use a 0 -140V step-up
type variac).  My system actually draws about 700 watts or so with
PFC (but I'm not using PFC).  So this system is actually performing
below my input watts equation.  This system is less efficient than my
original 42" spark TC because I made the secondary shorter to keep
the coil compact and portable.  This shorter secondary gives a 
poorer impedance match to the arcs, and also raises the gap losses.
I'm willing to accept these inefficiencies for this portable coil to keep
it compact.

 >It seems to me
> you could drive a larger toroid for greater arc length. Not much larger in
> pF, but a bit. Have you tried this? Also, I think a few more bps would
> help, but you can't go too far with it before the energy at the toroid
> actually decreases (240 is just about maxed out with your current setup).

The spark barely breaks out now.  If the smooth toroid was any larger
the sparks would not break out.  However with a corregated toroid, it
can be considerably larger.

> I know you've tried higher bps in the past and you were not impressed. I
> believe there is optimum bps rates for each coil determined by the entire
> system, including the top load.

Not only was I not impressed, but the whole system was much less
efficient.  I got 20% less (or whatever, I'd have to check my notes for the
exact figure) spark length for the same power input at 240 bps.  During
these break-rate tests, I tried a variety of different top load sizes, and
it didn't really make any difference to the results.
 
> Bart
 
> P.S. Beautiful job on the TT-42.

Thanks !

John Freau
 
> Take care,
> Bart >>