AC Input:

15 Amp Variac, 30 Amp RFI filter, 88 uF 370VAC PFC caps, MOV transient suppressor.

HV Xfmr:

15KV 60 MA neon sign transformer, de-tarred and re-potted in Vaseline.

HV Xfmr protection network:

Per HV Xfmr lead to RF Gnd:

- 450 pF bypass capacitor constructed of .09" copper-clad G10 circuit board material. Vaseline for corona suppression (Yuk!)

- Two 0.25" wide safety gaps using 3/8" diameter brass balls

Per HV Xfmr lead in series:

- 1.6Kohm, 113W non-inductive resistors, to form low-pass R-C filter with bypass caps.

Grounded Strike rail: - 1/4" Cu tubing, 2.75" above top primary turn

Spark gap:

A one-segment static gap, spaced 0.34-inches, massive airflow through spark channel provided by a vacuum cleaner motor.

Tank Capacitor:

.011 uF homemade "MMC" Multi-Mini Capacitor, constructed out of 192 0.015uF/1600VDC polypropylene capacitors, in parallel with a .01uF/100KVDC FCI brand commercial cap from Fair Radio Sales. Total tank capacitor value is .021uF.  More recently I scored a used Maxwell .02uF 45kV (p/n 37093) cap, which I use by itself.

Primary coil:

14 turn 15-degree conical spiral 1/4" copper tubing, 1/4" gap between turns (.5" ctr-ctr), 6.25" ID, 20" OD. 54uH when tuned for 2-toroid topload.

Secondary coil:

4.25"D x 23.25"L (approx 871 turns) 22 AWG wound on 1/16" wall dried/sealed PVC SDR drainpipe. Many layers polyurethane. Low voltage self-resonant with no topload at 489 kHz. C-self = 8.4 pF. With 4.5" x 15.5" toroid (23.9 pF), Fr is 290 kHz. With additional 6" x 23" toroid (total topload of 46.5 pF), Fr is 190 kHz. Lowest turn is even with lowermost primary turn. 12.9 mH inductance.

Coupling constant - k:

With bottom turns of primary and secondary at same level, k=0.139. Raising the primary up by 0.25" changed k to 0.144.

Discharge terminal:

Small 4.5" x 15.5" toroid made from aluminum flex duct, stiffened and smoothed with 2-part wood filler and spakel, covered with aluminum tape.

Large 6" x 23" toroid made from aluminum flex duct, covered with aluminum tape. This toroid is placed on top of smaller one.

Ground system:

One 8 foot ground rod in earth soaked with water, connected with 15'L x 2"W copper flashing ground strap.

Performance to date:

Max sparks to grounded target (foundation wall): 58"

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