The catkin featured here has an external metal shield. Other MH4's in the collection are without this screening feature. The MH4 was designated as being for detector service in radio receivers.

The shroud is plated to give a bright appearance, long since faded in this exhibit. The top is enclosed by what looks to be a pierced paxolin disk.

The outer metal shroud is 32 mm in diameter, and excluding the B5 base pins is 97 mm tall.

 
Pin Connections

B5	1	2	3	4	5
	a	g1	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 08 June 2007 {find valves by name}