CT100 Convergence Transformer Solid State Replacement Update

[Penthode]

I was not content with the edge convergence so I conducted further testing. This has led to some modifications which resulted in better overall convergence. I think overall it is now better than I ever had with the transformer.

I added a 220kohm resistor in series with the output and changed the external resistors to 1.0Megohm and 620kohm. I also changed the coupling capacitor from 0.1uF to 0.47uF.

Convergence on old color sets is a process of going around around and around making marginal improvement which interact with other adjustments. Creating accurate parabola waveforms with crude circuits like this is often an exercise in futility. I am happy the new circuit has the range and control to fix the top and bottom convergence with a reasonable interaction with the horizontal parabola.

Anyhow this is likely my last post on this subject and I am very happy with the result. This proves to be a viable cost effective and technical solution to the vertical transformer problem.

The CT100 has been running for about four hours straight and apart from minor convergence drift from switch on for 10 minutes, the convergence and focus has been stable.

Please find attached the documented modifications plus a couple of screenshot I took this evening. I have also included photos of the installed transformer. the color of the wires follow the diagram.