Sensibly equivalent¶ to:
The MH4 is an indirectly heated amplifier triode. The MH4 was also produced in Catkin form in 1933/4. The glass envelope version has a totally different electrode construction but gave the same results. The Catkins were excellent valves but were more expensive to make and were phased out after a few years.
The identification is printed onto the metallic paint screening.
The balloon envelope is 50 mm in diameter and, excluding the B5 base pins, is 113 mm tall.
References: Datasheet, 1005, 1043, 3002 & 1040. Type MH4 was first introduced in 1929.
Absolute Maximum Operating Conditions¶
Updated April 05, 2015.