[Penthode]

Thanks Chris.

After earlier toying with a transformer rebuild and pondering the focus and convergence high potential had to traverse over 2 /1/2 miles of AWG #44 wire to reach the CRT with the strict insulation requirements, it seemed appropriate to examine an alternative approach requiring capacitive coupling. My alternative approach is much simpler and cheaper and in my opinion works better.

I have been running tests. I have gotten the convergence best I can on my tube. It matches what I was able to get prior to the transformer failure. It has the benefit of less drift: from switch on to warm up there is very minor drift which is due to the 12AU7 coming up to temperature. The convergence becomes optimized at about 4 minutes and holds well after that. I have been running the set for two to three hours at at a time and the convergence box remains cool.

Here is a snapshot of the crosshatch with the convergence about the best I can get. I could never get the lower corners as good as I would like but as it is a rebuilt tube and I am extremely fortunate the tube is still good and appears to have a lot of life left, I am extremely grateful with what I have.