Osram B21

ST shape double triode

Osram B21

Near equivalent to the PM2 (Data 1, Data 2). The only data I have for this valve comes from the AVO Valve Data Manual, 15th. 1962 edition. The filament voltage is 2.0V. At Va=150 Vg1= -3, anode current is 5 mA and gm is 1.5 ma/V (mS). This valve was used for QPP (quiescent push-pull) output. It has a B7 base.