Sensibly equivalent¶ to:
The VT20 battery triode was designed as an audio output valve. With a maximum output of 190 mW it would be used with headphones and not a loudspeaker.
We have two versions of this exhibit, this one is the later of the two and looks M-OV in shape, despite the Cossor marking, and is fitted with a standard M-OV base cap of WWII period. For the earlier example see VT20.
The Cossor 220P was initially called the Stentor Two when introduced in 1927.
The balloon envelope is 40 mm in diameter and, excluding the B4 base pins, is 83 mm tall.
References: Datasheet & 1043. Type VT20 was first introduced in 1929.
Absolute Maximum Operating Conditions¶
Updated December03, 2012. shape:balloon construction:pinch type:triode age:1920.1930 base:b4 heater:2.0v pins:4 pin:1.a pin:2.g1 pin:3.f pin:4.f