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MH4

Sensibly equivalent to:
41MTL AC/HL AR17 CV399 CV1037 D4 HL4 MH4K NR31 VR37
See also:
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.
Our other Marconi baloon envelope MH4 has external metalising.
Through the blackened glass one can make out the mesh anode, grid and indirectly heated cathode.
The Marconi paper label.
The dome of the glass has the identification etched into it but no brand name. This way M-OV production was branded just by adding the paper label - Marconi or Osram.
A closer view.
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.

 

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 May 13, 2016.
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