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MH4

Sensibly equivalent to:
41MTL AC/HL AR17 CV399 CV1037 D4 HL4 MH4K NR31 VR37
See also:
Quality Amplifiers - CV1037 short entry - CV399 short entry
    
Extras ▼

 

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: Data-sheet, 1005, 1043, 3002 & 1040. Type MH4 was first introduced in 1929.

 

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 PDF datasheet.
Updated November 10, 2020.
shape:balloon construction:pinch type:triode age:1920.1930 base:b5 heater:4.0v pins:5 pin:1.a pin:2.g1 pin:3.h pin:4.h pin:5.k
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