UTC A -25?
hmmmmm, lets see....
cj constants say B max = 2.42 * 10^8 E/(Area in^2)(Turns Squared)
Now all we need is the cross area of the core in inches, the turns, and the applied rms....I guess you would need a blueprint, unless somebody has been inside one of those things....
Wait, I have! Thats a twice stack 50 FG lam, half nickel, and 5000 turns on ther primary.
FG lam has 1/2 inch tongue, so twice stack = 1/2 time 1 = 1/2 square inch.
Turns squared is 25,000,000, so
B max = 2.42 * 10^8 E/(0.5)(25,000,000) = 2.42 * 10^8/12,500,000
B max = 0.01936 times your rms volts on the plate of the ay7.
Lets say you are close micing Pavarotti for the full swing of say 300 volts RMS, that ought to give us some leeway...
300 time 0.01936 = 5.808 kilo gausses, just perfect for 50/50, which has a flux pain load of 10 K gausses.
But wait, you know what that dc does to an SE xfmr, so derate it by at least least 50% and we should have a nice, "warm" transformer sound at full wada.
Whats with the 8 ma? My manual says 3 ma for an ay7?
Lets see if the turns on the A 25 match the chart:
I saw 900 t of sec, and 5000 t of pri.
If the 900 t is supposed to be 500 ohms out, 5000/900 = 5.55 turns.
Turns squared is impedance, so 5.55^2 = 30.86.
30.86 time 500 is your plate load, thats 15,430 ohms pri imp.
What does the book say? My site's down rt now.