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Seren 2000 watt RF driver supply

nu instruments torch box:

The feedback pot and the vacuum capacitor don’t hit end-stop at exactly the same location, so the highest tuning frequency (and any programmed values in your SW) may be slightly different now.

From device behavior, the plasma seems to be a six-ohm ring (it forms a transformer, where the plasma is the one-turn secondary coil, and the water-cooled coil is the 3-turn primary.  )  Might be forty amps in the water cooled coil, and a bit under 3X higher inside the plasma.   If so, then the coil’s temperature isn’t just from plasma’s light output.

Crude numbers…  (40 amps x 3 )^2 / 7 ohms = 2000 watts

For simulation, it’s a series-resonant tank circuit with 86pF capacitor (measured) and ~400nH inductance for 27MHz resonance. To match to 50 ohms, a large capacitance is connected across it, roughly 450pF, Varied +-50pF via the screwdriver shaft.  The output coil looks like ~20 ohms real resistance when plasma is lit up (in series w/400 nH inductor.)