RCA PA transformer confusion

[Phil_S]

I don't understand what I'm seeing here. I was given an old RCA PA that looks like a nice platform for an amp, but not useful as built. So, I began to tear it down and isolate the transformers so maybe I can see what I'm working with. The amp had several preamp tubes and a pair of 6L6. The choke is too small to be for choke input (guessing), so I figure it is a screen choke. The wiring on it was very strange...back to the question.

The PT HT with no load is 838VAC. (It is center tapped.) I recognize this will come down under load. The amp used a 5U4GB. I will have to build out the power supply and test it with a couple of 6L6 to see what it really produces. That will come later. I just can't imagine plate voltage much over 400. We'll see.

Tonight I tested the OT for turns ratio. The 4z and 8z taps have turns ratios that tell me the primary is about 6.6K. The 16z math works out to about 7.2K. For this question, let's assume 6.6K.

What sort of 6L6 plate and screen voltage would be appropriate for a 6.6K primary? Obviously, I'm trying to figure how these two transformers got put together in this amp. They appear to be original.

Thanks for any comments.

Phil