Interesting thing about Tube Coil oscillators...

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Original poster: "David Trimmell by way of Terry Fritz <twftesla-at-uswest-dot-net>" <davidt-at-pond-dot-net>

Hello all,

I was doing some testing of various VTTC configurations last night, and
thought I would try a "tankless" configuration. Running the output from
the Level Shifter (normally the B+, but in this case we are using the tube
to self-rectify HV AC) into the base of my solenoid Primary (23 turns of
PVC insulted #12 on 6" form 79uH measured), the top of the primary was
connected to the plate of a single 833C. Grid coil with 22 turns of PVC
insulted #22 wire is 3/4 inch above secondary, with 4 to 25 K resistance
for bias, 0.001uF mica cap in parallel. Using this configuration the coil
will oscillate, producing 3-4" discharge with 4800V on the plate. Power
consumtion was high ~25 Amps from wall at 40 volts into the PT (60:1), but
grid current was low, even with only 4 K resistance, less then 30 mA. It
is quite intesting how I can get a coil that is self resonant at around
380KHz to produce this discharge. I am asuming the parasitic capacitance
in the primary is working here? BUT that would put the Fr0 in the many
Megahertz range!?

Anyone have agood explaination of what is really going on here?

Regards,

David Trimmell