[Penthode]

I am now looking for an audio transformer with 2:1 ratio. Checking my junkbox right now.

Here is the proposed circuit. The capacitve coupling seemed to work okay with anticpated waveform. And the circuit almost achieves the convergence required with insufficient at 350v p-p. I suspect if I can get 450v to 500 v p-p that will do it.

I like the capacitive coupling with the resistive division. Focus is good across the screen. And the capacitive coupling means the transformer does not have to stand up to the brutal 3 to 4 kV.

And is the mosfet needed at all? Maybe the transformer only?