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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.
MH4 is an early glass enveloped version with the older style balloon envelope, this exhibit shows the progression to the shouldered envelope and mica supports that are an interference fit into the top of the envelope and thus hold the electrode assembly rigid.
The Marconi name was printed onto the plain zinc paint.
The classic envelope is 45 mm in diameter and, excluding the B5 base pins, is 93 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 November 18, 2016.
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