Re: Latest coil

In a message dated 99-09-05 06:27:04 EDT, you write:

<< foil that measures 4"x33", and two flexible ducts taped end to end for
> 7"x 40". I am using two of the H&R transformers that are wired
> anti-parallel for 10kV 300ma. Six sets of polypropylene caps, .013uF
> each for .078uF or so total and a sync-gap. This isn't quite resonant
> yet, but will soon be larger than resonant.

Hi Alan,

I wonder if it might be best to keep the system near resonant because
of the relatively low voltages from those types of xfrmers?  LTR might
have trouble jumping the gaps reliably possibly?
> The first run was just to see that everything worked. There were
> serious racing sparks and as I found out, several spots had burnt.
> Some turns had to be removed on the bottom and the other spots had the
> burnt insulation scraped off and were coated with model paint. Trying
> again the next night, one of the repaired spots burnt again and three
> turns had to be removed. But there was a ground strike before shutting
> down that I later measured at 80". Or 3.2 times the winding length.
> Pretty decent, but will have to get better :-)

Those are the longest sparks I've heard of anyone getting from those
xfrmers, congratulations !!  It must be the large toroids that are helping.
You're pretty close to the max capability of that secondary probably.  I've
also had problems with racing sparks etc with a wide short secondary and
long sparks.    I wonder if it would help to add a small toroid (20" dia.) 
on top of the secondary, or a little above, then stack the others above, or
even use a transitioning cone like Richard Hull uses on his magnifier.  I
don't know how much difference this makes.  But when I did my experiments,
"capabilities of small thin wire secondaries", the placement and arrangement
of the various toroids at top made a big difference for breakdown and 
spark length.  
> I setup again tonight with the newly repaired secondary, freshly
> soldered and re-painted. More racing sparks and some that jumped
> straight down to the primary from the lower toroid. Since I have never
> had these kinds of problems, I didn't really know what to do. I have
> only run with crappy capacitors before that wouldn't let the power out
> to the coil and these polypropylene caps are working great. I tried
> raising the secondary some more to reduce the coupling. It was now
> 1-1/2" above the primary, but still had the racing sparks. The only
> other thing I could think of was to lower the toroids some. Now the
> racing sparks have been eliminated. But the spark length dropped,
> probably from the reduced coupling. I'll try increasing the coupling
> in a few days and see if the spark length comes back up.

Racing sparks depend on bang size.  With a 120 bps system, the
bang size will be necessarily large, so the system must be built to
withstand this.  With a low bps system,  there's none of this little
tapping with a little hammer.....you're using a sledgehammer so to
speak.  That's what's good about it, and that's what demands extra
care in the set-up.  If you increase the coupling, the racing sparks 
might come back.  You might be maxed out on the system pretty
much.  The only absolute cure might be a taller secondary if you 
have the room.  Thanks for the report, let us know what happens, 

John Freau
> So, any comments or suggestions? All welcomed.
> Thanks,
> Alan Jones >>