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intial coil contest results



Original poster: "Laurence Davis by way of Terry Fritz <twftesla-at-qwest-dot-net>" <meknar-at-hotmail-dot-com>

decided that I was going to do things the wrong way to learn something.
but wanted to follow the rules.

gary laus updated contest rules page listed 50ma 4kv.  I achieved this
by keeping 6 top and 7 bottom shunts.  but I heard in the list that someone 
removed just half of the shunts available.  I had 17, so that would leave 8 
top and 9 bottom.  that must be necessary because the nst
secondary is so hot that I cant keep my finger on it for more than a second 
or so.  (its also making a sizzling noise[no its not on], which would be 
kewl if I didnt have 50bux invested in it)

keep in mind, I wanted to do everything wrong... to learn something.
coil parameters.
secondary 4.5" x 18" with 30awg heavy build. 7 coats poly.
primary 7 5/8" sonotube, approx 13 turns 12 awg stranded,spacing 1/16"
cap 27.5nf. (way wrong cap bc calc was on 38ma instead of 50ma)
bottom turn of helical pri is even with secondary bottom winding
(which means 0 coupling spacing above/below sec)
topload: 1.5" x 8" toroid covered in al tape.
spark gap, multi stage static gap using fender washers, carriage bolts and 
a 2x4.  gaps adjusted to approx .005-.015, attempted max number of gaps to 
fire at 60%............

results?  the helical primary is nothing more than scrap wire duct taped
to cardboard, so its kinda hard to tune. tape, run, untape/retape, run...
lotsa racing, both from pri to secondary and between secondary windings.
open air arcs are about 2-3", once or twice I tuned it enough
to get 6" open air arcs.

just now I got about 8" arcs to a grounded object -me-.  used a wrench
with open end pointed to toroid.  got a zap from my foot on the bedspring.

keep getting zapped on the variac.  wonder if thats cause the core 
connection for high side is secondary ground also?

racing limited to almost nothing when I put two 1/8" screws in core to 
limit current.  the core still heats up appreaciably though.  maybe I'll 
check output current of nst with two screws added.

I think thats a new one. current limiting via screws.

any thoughts about current output for contest?
larry.