Gary Lau's mini coil:

NST: Franceformer 4kV/20mA, shunts removed to yield 38mA Isc

Tank capacitor: A .025uF/8000VDC MMC cap, made of four .0.10uF/2kV, Cornell Dubilier polypropylene caps in series.  A 10Meg 1/2W bleeder resistor is across each cap.

Primary: A close wound flat spiral of insulated solid 12AWG wire.  I.D. = 3.25", O.D. =6.5".  Turns were hot melt glued to the Lexan support plate.  Fixed taps at turns 6.5 through 14.5 are terminated (soldered, not crimped) to male Fast-On terminals, for secure but easily changed connections.  Best performance with present top load at tap 6.5.

Secondary: 1.9" O.D. PVC pipe,  9.5" winding length (~1100 turns) of #32AWG magnet wire, polyurethane coated.  Measured inductance is 10.4 mH

Pri-Sec coupling:  TBD, 1st secondary turn is 0.25" below the plane of the primary.

Gap: A single static cylinder gap - Two 1 1/8" diameter x 3" long copper pipes, spaced 0.05".  Initial testing showed no benefit to adding forced airflow, but I later found a small fan from a microwave oven which fit nicely.  While maximum streamer length did not seem to improve, the streamer brightness and loudness did noticeably improve.

Top load: 3.5" x 10.75" toroid, made from corrugated aluminum duct, smoothed with paper mache and covered with aluminum tape.

System resonance is 392 KHz

Best performance:  Occasional strikes to a grounded chicken wire target, 14".