Sensibly equivalent¶ to:
The MH4 or MH4K 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. Catkin versions were introduced in 1933 and 1934.
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.
References: Datasheet, 1005, 1043, 3002 & 1040. Type MH4K was first introduced in 1933.
Absolute Maximum Operating Conditions¶
Updated October 20, 2013. shape:catkin construction:pinch type:triode age:1930.1940 base:b5 heater:4.0v pins:5 pin:1.a pin:2.g1 pin:3.h pin:4.h pin:5.k