The Cossor 220OT is a battery output pentode and dates from the 1930s. The 220OT could deliver 0.5 Watts of audio.

The electrodes are housed in a large bright box shaped anode and are held by a mica disc. This indicates an oxide covered filament as the older Azide process did not allow for mica supports. The filament can be seen under a glass as a pair of inverted 'V's and the grids are thin wire structures. The control grid is tight across the supporting rods and thus passes close to the filament. The other grids form spirals. All are made from thin bright wire.

The classic envelope is 50 mm in diameter and, excluding the B5 base pins, is 104 mm tall.

 
Absolute Maximum Operating Conditions

Pentode	Vh	Ah	Va	Vs	Vg	mAa	mAs	gm
	2.0	0.2	120	120	-4.5	4.3	-	2.5,

This exhibit was last updated on 01 July 2006