The Cossor DD4 is a low current low voltage indirectly heated Double Diode. The 4.0 Volt heater was the standard for UK mains valves in the 1930s before the American 6.3 Volts standard took over.

Seen from the back the electrode structure is revealed. The heater wires can be seen entering the cathode cylinder. The anode has a centre cylindrical space and the fins help dissipate the heat generated as well as making mounting easier. The pinch can clearly be seen rising from the Bakelite base.

The Balloon envelope is 30 mm in diameter, and excluding the B5 base pins, is 71 mm tall.

 
Pin Connections

B5	1	2	3	4	5
	a(1)	a(2)	h	h	k

 
Absolute Maximum Operating Conditions

Diode	Vh	Ah	Va	mAa
	4.0	0.75	100	10.0

Thanks to Frank Philipse for supplying the above datasheet

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This exhibit was last updated on 09 June 2007 {find valves by name}