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MHL4

Sensibly equivalent to:
154V 164V 41MLF CV1038 CV3547 NR26 VR38
See also:
CV1038 short entry - Valves for Superhets - Adding AVC to the Monodial Super
    
Extras ▼

 

The MHL4 amplifier triode (mu = 20) was not much used in domestic radios because the MH4 (mu = 40) was better suited to the detector/first AF task. However, the MHL4 did see service in professional and military applications over many years until it was superseded by the L63, which had comparable characteristics.
The MHL4 was marketed from about 1930. It was certainly a year or so behind the MH4. The specimen shown looks 1940-ish. Early MHL4s were taller and bulbous, and were available either with B4 base caps + side terminal or with B5 bases.
The internal coatings obscure the inner structure.
The classic envelope is 44 mm in diameter and, excluding the B5 base pins, is 97 mm tall.
References: Data-sheet, 1040 & 1043. Type MHL4 was first introduced in 1929. See also 1929 adverts.

 

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
-8
8.0
8,000
2.5
Thanks to Frank Philipse for supplying the above PDF datasheet.
Updated July 30, 2022.
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