This Marconi/Osram MH4 valve was a manufactured as a Catkin. The Catkin construction was derived from the large Cooled Anode Transmitting valves, and these also featured a shaped copper anode sealed to a glass envelope.

The date of design was 1933 and was clearly designed for use in all-mains radio receivers.

The design was also with a conventional glass balloon envelope also with the designation MH4.

The thin metal tube envelope 25 mm in diameter and, excluding the B5 base pins, is 95 mm tall.

 
Pin Connections

B5	1	2	3	4	5
	a	g	h	h	k

 
Absolute Maximum Operating Conditions

Triode	Vh	Ah	Va	Vg	mAa	ra	gm
	4.0	1.0	250	-4	5.0	11,100	3.6

Thanks to Frank Philipse for supplying the above datasheet

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This exhibit was last updated on 05 January 2008 {find valves by name}