And there lies the missing piece of information.  We do not fully understand or appreciate the capacitive
element of the Ruslan, Sergey, Akula, Dally, etc  circuits.  Maybe the type of insulation on the wire
is important, or how tightly/loosely the coils are wrapped.

I highly recommend (unless you already have a self runner), replicating what Woopy demonstrates here:
https://www.youtube.com/watch?v=94yCfy8z4lc

Then replace the split rolled copper with various coils arrangements.  It is fairly easy to do and will
provide a means to better understand the capacitive side of these devices.  Take measurements;
look at the waveforms, but be careful not to blow up your scopes.  You might even discover a way
to significantly increase output beyond what the rolled copper plate produces.  That would be a
huge step in the right direction.  Try different things, bucking coils, mini grenade coils, heavy
insulated and straight magnet wire.

You may also want to determine the running frequency of the Kacher driver and replace it with
a signal generator to see what effect the changing capacitance has.

I'm pretty convinced as I mentioned recently what these devices must be doing, but I'm a long
way away from understanding how it does what it does.  Experimenting may be the only means
to shore-in this understanding.

Hi Dog-one. Thanks. I had already seen that video a couple of years ago or so.
I don't think what Woopy is showing there is really any much different than what I
was doing in my recent tests, except Woopy's kacher arrangement was drawing a
fair bit more input power. I think it is the same types of effects at a bit higher power
consumption level. I therefore doubt there is any OU there.

If it's any use I made this device 5 or 6 years ago, it lit the 40 watt bulb dead easy but it was not overunity.

There comes "magic" when you drive Tesla coil with less than 20% duty cycle. The heating element does not have much difference from between 50% or 5% duty cycle pulses coming to it...