Hi John,I tried a test configuration yesterday, to no avail. With just 12V it was difficult to establish even a brief arc, let alone anything stable. The setup was a piece of heavy gauge (12awg I think) wire meeting a piece of pencil lead. I made a crude adjuster bracket and screw mechanism to control the gap. The series tuned circuit (365 pF variable, and a ferrite Rod coil) was connected across the gap.
I do think it got close, but no sustained oscillations yet - at one point there were some vaguely "tuned" scratchy noises on the nearby radio (tuned to ~250 kHz, USB). A little like brief snippets of switch mode power supply noise. Otherwise it was just the broader band crackling from sparks, filtered somewhat by the tuned circuit.
I think a beefier electrode configuration may help - it was easy to drive the pencil lead to a bright red/orange glow... at which point the copper would oxidise. More power might be do-able with an extra battery.
All of which makes it more fascinating to think they made this work so well in the early days.
More as progress & time allows.
Ed