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 reverse is plain screening paint.
The dome carries the identification but is almost illegible. The balloon envelope is 50 mm in diameter and, excluding the B5 base pins, is 114 mm tall.References: Data-sheet, 1005, 1043, 3002 & 1040. Type MH4 was first introduced in 1929. See also 1929 adverts. |
