Re: Latest coil - update

Hi John,

> Original Poster: FutureT-at-aol-dot-com 
> In a message dated 99-09-10 07:57:24 EDT, you write:
> << was placed between the transition cone (hey, it sounds better than
> > dishpan) and the dryer-duct toroids. The breakout point on the top
> > toroid was somewhere around 15" above the top winding of the
> > secondary.The racing sparks finally stopped with this setup. But there
> > was still a lot of corona around the secondary, just no sparks.
> > But I am only getting 70" sparks now. Lost 10" of spark by doing these
> > things. I wonder if it is worth losing that much spark length? 
> >Alan
> Alan,
> I wonder why those changes would reduce the spark length?  I
> didn't expect that.  It could be that the total secondary and toroid C
> is now just too large for the amount of power, that's my guess.  
> I suspect that if you built a new secondary that is narrower, maybe
> 8" or 9" wide, but taller at maybe 32" or so, then use the toroid combo,
> it would work well.  I say this because when I once used a wide short
> secondary, it both developed racing sparks, and demanded a smaller
> toroid.  I suspect that if the power is limited, the total combined 
> secondary and topload C shouldn't be too large.  (if one is larger, the
> other must be smaller and vice versa).
> In general, I found wide short secondaries to be *troublesome*.  But
> it's mostly the shortness that causes the real trouble.

I agree.  Some of the secondaries I wound years ago were going to 
be the best thing since sliced bread. Short and wide, plenty of visual 
appeal and a heap of inductance. Well, they are great - for 
magnifiers but hopeless for two-coil secondaries.  On the other side 
there are the unexpected surprises. Possibly my best "small" 
secondary is a 6.5" x 32" HDPE coil closewound with about 850t of 
0.9mm wire. Inductance is a modest 20mH or so. However, it has 
the voltage handling capacity, not too much self-capacitance and 
quite a high Q because of the thickness oif the winding. I laugh now 
when I think back to the time I wrote this coil off as the worst I had 
built because of the higher aspect ratio (worst that is besides the 
thin wire 1800 turn job which crammed mH's+ of inductance into no 
volume at all).