New carbon rods arrived, and in place of the copper wire anode, I tried a piece of 1/4" brass rod Sturdy connections were made to both (there is quite a bit of heat generated).Control of the arc separaion was by hand. Not ideal, but there was no opportunity or ready material to hand to fabricate a mechanised advance. Not pretty, but it does sort of work, and allows the current to be cut off quickly should anything untoward be observed.
The coil had an extra layer added, allowing the frequency of the LC circuit to be adjusted to 100 kHz.
Results were interesting. "listening" Was performed with a Lowe HF-150 in active whip antenna cofiguration With the receiver in USB mode, positioned about 3 ft away, the obvious crackles could be heard as connection between the arc electrodes was made and broken. However, when something approaching a sustained arc was achieved, tuning the "transmitter" resulted in a swooshing sound that swept in and out of the receiver passband. Not a continuous wave/pure tone, as we might understand it, but this was definitely a band of noise that tuned relatively sharply and had a changing tonality as tuning varied, suggesting some discontinuous but tuned damped oscillations.
More inductance will be the next test. Also an attempt to get a sound sample.
Ed
Ed