Sensibly equivalent¶ to:
This MH4 catkin does not have the K suffix to denote the external anode design but is identical to the MH4K.
The MH4 was designated as being for detector service in radio receivers. Catkin versions of the 1929 MH4 were introduced in 1933 and 1934.
The identification label is missing and could have been Osram or Marconi.
The outer metal shroud is 34 mm in diameter, and excluding the B5 base pins is 97 mm tall.
References: Data-sheet, 1005, 1043, 3002 & 1040. Type MH4 was first introduced in 1929.
Absolute Maximum Operating Conditions¶
Updated November 10, 2020. 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