Re: Improvement with bigger secondary

From: 	FutureT-at-aol-dot-com[SMTP:FutureT-at-aol-dot-com]
Sent: 	Sunday, August 10, 1997 10:43 AM
To: 	tesla-at-pupman-dot-com
Subject: 	Re: Improvement with bigger secondary

> I have finally completed my new 6" dia secondary (previously 3.5") and I
> was rapt to find that the max spark lengths are now 9" longer than
> before.
> All other parameters were left the same where possible - 60Ma 15Kv,
> ..011uF Cap, 6" by 22" secondary with about 900 turns of 22gauge and same
> 20" by 8" toroid but I had to add some turns to the primary, it now
> tunes around 14 turns. Spark lengths have gone from around 30" to 39"
> and as many sparks seem to break out at once, I may get more with a
> bigger toroid. The calculated freq. of operation has halved to around
> 160Khz but I have yet to verify this.
> All this seems to suggest that either lower freq coils do indeed produce
> longer sparks or that larger coils are somehow more efficient. Anyway,
> to all you new coilers out there, I would suggest not to bother with
> "thin" secondaries, unless you are only building tabletop coils.
> Cheers, Peter E.


Thanks for this informative report.  This is the kind of research that
is very useful in finding the best way to build a TC.  I have always
advocated the use of wide secondaries, and I also find them to be
better.  If you used the same wire gauge, then you now have a lot
more inductance in the secondary...so the question is...is it the 
lower frequency or the higher inductance that is helping the most?
I would guess that the inductance is helping the most...but I'm not
sure.  There's also the question of coupling...did you optimize the
coupling for both coil designs?  There's also the fact that the primary
now has a higher surge impedance and this can help the quenching
of the gap, which will help performance...still another factor to consider.

John Freau