Sensibly equivalent¶ to:
The Cossor 220PA is an interesting audio output triode valve. A look at the envelope reveals two triode sections in parallel within the glass envelope in order to reduce the impedance and thus increase output. This was not uncommon in the early 1930's but this looks to be a much later valve in that it uses the mica bridge and classic envelope.
The filaments appear to be oxide coated and each section contains a single inverted V. Above the top mica are bright coil springs with hooks that hang from the top of the coil down through the middle and provide a tension force for the filament.
The 220PA battery triode was a popular type and had many equivalent types. The 220PA produced 0.18 Watts.
Power was a wet accumulator for the filament and a dry battery for the anode supply.
The classic envelope is 43 mm in diameter and excluding the B4 base pins it is 93 mm high.
References: Datasheet & 1043. Type 220PA was first introduced in 1931.
Absolute Maximum Operating Conditions¶
Updated August 24, 2015.