The W3 from Cossor is a dull emitter audio output valve from 1925 and features an oxide-coated filament.

The top of the envelope is painted green and inside the glass the Cossor parabolic anode can be clearly seen.

The W3 came in the original box. The image on the box shows that the electrodes followed the same pattern as the earlier valves but with the larger anode for the filament to work in a central support was added.

The box also carries the basic operating parameters of the W3.

The wide glass tube envelope is 28 mm in diameter, and excluding the B4 base pins is 84 mm tall. The base is 32 mm in diameter.

 
Pin Connections

B4	1	2	3	4
	a	g1	f	f

 
Absolute Maximum Operating Conditions

Triode	Vh	Ah	Va	Vg	mAa	ra	gm	μ
	1.8	0.5	150	-4.5	-	12,000	0.62	8

This exhibit was last updated on 27 December 2008