Sensibly equivalent¶ to:
The 220PT is a battery output pentode from the 1930s. With the correct anode load of 7500 Ohms this valve can deliver one Watt at 8% distortion.
The screen grid is taken to the side terminal.
The original B4 based 220PT was issued in 1932 with the B5 based version released a year later.
The balloon envelope is 45 mm in diameter, and excluding the B4 base pins is 95 mm tall.
References: Datasheet & 1043. Type 220PT was first introduced in 1932.
Absolute Maximum Operating Conditions¶
Updated August 24, 2015. shape:balloon construction:pinch type:pentode age:1930.1940 base:b4 heater:2.0v pins:4 pin:1.a pin:2.g1 pin:3.f pin:4.f