Sensibly equivalent¶ to:
The Pen44 is a beam tetrode audio output valve for single ended or push-pull applications. The valve specification allows for up to 18 Watts anode dissipation and suggests self bias operation rather than fixed bias.
The BTH SUPA projector amplifier used Pen44's originally.
The top view of the valve shows both the etched lettering and the top mica holding the electrodes firmly in the dome of the envelope.
Thanks to Leif Ekornrxd (LA9IM) for the pictures. Click here for Leif's site.
The classic envelope is 54 mm in diameter, and excluding the MO base pins is 100 mm tall.
References: Datasheet, 1040 & 1043. Type Pen44 was first introduced in 1939.
Absolute Maximum Operating Conditions¶
Updated February 23, 2017. shape:classic construction:pinch type:beam.tetrode age:1930.1940 base:mo heater:4.0v pins:8 pin:1.h pin:2.k pin:3.a pin:4.g2 pin:5.g1 pin:6.m pin:7.- pin:8.h