Used with approx.100mA current, in class A1 with 6-10k primary OPT´s. 833A pdf
I was curious, why this tube has so much attention. I can fully agree with amplifier builders. If you give it A2 drive, 1500V on plate, then you can get 75W with low distortion. On a 5k load (affordable Hammond 1642SE comes to mind)
Very interesting and dangerous amplifier, with nice sound.
(left: class A1@15W right: class A2@75W or more) Distortion is surprisingly small.