Brett Miller -- 6 Inch Coil Stats:
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SECONDARY COIL
Coil Form - 6 inch green Drain Flume PVC
Diameter - 6.25"
Winding Length - 24"
Wire Gauge - Awg 23
Number of Turns - 1031
Secondary Resonant Frequency - 149 KHz
Secondary Inductance - 38.7mH = 38721uH
Secondary Self Capacitance - 10.9pf
Coupling Coefficient - 0.1945
Toroid Capacitance - 18.7pf
Secondary Cself - 10.9pf
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C total - 29.5pf
PRIMARY COIL
Number of Turns - 14
0.25" copper tubing
0.25" spacing between turns
30 degree saucer configuration
Primary Inductance - 92.48uH
Primary Resonant Frequency - 148KHz w/MMC
PRIMARY CAP (MMC)
2 strings of 9 0.056uf 1600v Panasonic
foil/poly caps in series for a total of
0.0124uf at 14400 volts. 10meg ohm 1/2 watt
Yaego Carbon Film resistors were placed across
each cap to bleed off excess charge.
SPARK GAP
Standard TCBOR with up to 6 gaps available.
When the total gap spacing is measured I will
make that information available.
I should say that I do run the gaps extremely
wide. The cap probably rings up to 25000 volts
or somewhere in that range. So far I haven't
lost an NST yet in over a year of firing this
coil with a wide static gap.
POWER SUPPLY
1 unmodefied France 12/60 NST, powered through
a 0-140 volt General Radio 20 amp variac.
RF GROUND
One 1.5" dia copper pipe about 3 feet long, pounded
all the way in the ground, about 12 feet from the
coil.
TOPLOAD
4" x 17" Dryer duct. Directly underneath the duct
toroid I use an ACR (Anti Corona Ring) made of a
foam "Fun Noodle" wrapped around a foam disk and
covered with aluminum tape. The dimensions of this
ACR are 11.75" x 2.75". To date I have had no strikes
to the primary despite the 30 degree incline and lack of
a strike ring.
MAXIMUM ARC LENGTH TO DATE
45 inches. 1.7 x SQRT(720) = 45.615785
Usually arcs are around 30-36 inches, but when
I run all the gaps I can get 45" streamers and
an occational power arc to ground of that length.