CT-100 B1001599 Failed Convergence Transformer

[Penthode]

I had made a minor error in my second implentation. The Drain resistor in the diagram states 47k and I had inserted a 33k resistor. As drawn for the second test with the correct value of drain resistor, the output voltage is 200 v p-p with no evidence of any nonlinear distortion. That is a gain of 13 times which should be more than ample. Now on to the chassis. The attached photo shows the input vs the output.

There was a concern that the polarity of the applied parabola after the MOSFET amplifier may be inverted. I went back to the schematic and reasoned that the polarity after the inverting MOSFET amplier should be correct. I have attached a pictorial reasoning for my assertion.