[etype2]

I mentioned your recent comments to my friend Mike who has done 99% of the work on both the 21CT55 and the CTC-7. I myself can only do the basics. Mikes comments:

“The absolute high voltage rating for the 21AXP22 is 27,500 Volts and the design values are between 20,000 and 25,000 volts. I set yours for 21KV which produced good focus. And the Grid 3 volts (focus) volts will rise linearly with the high voltage since that voltage is derived from the tripler set of 3A2 tubes. And THAT grid has a maximum rating of 6600 volts which you do not want to exceed. And YES, the set will produce 30KV with the regulator pulled. I tested it that way when I was verifying the regulator functions. It does NOT mean that you run the CRT at that voltage!!! The regulator tube is, by definition, a SHUNT REGULATOR circuit. What that means is that it is designed to SHUNT the UNUSED high voltage to GROUND as a function of its design. There are no issues with capacitors as far as I could tell here. Are you having problems with the picture? You can look up the PDF file for the 21AXP22 if you want to learn more about its design values. There is a FUSE in the circuit to protect the flyback from overload in the event that it occurs.”

I will ask Mike to join in on the conversation as he is a VK member. He just had long needed surgery, so it might not be to soon.

Edit: I checked both the RCA and Sylvania data sheets and confirm the voltage figures cited by Mike. However, RCA states “25KV Max.”