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X42

Sensibly equivalent to:
15A2 41MPG A80A CV3576 FC4 MX40 VHT4
See also:
Pentagrid Converters - Replacing a Triode Hexode
    
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The X42 is a vari-μ heptode oscillator and mixer or frequency changer. A design known in America as a pentagrid converter.
The oscillator and mixer share a common electron stream. g1 is the oscillator control grid with g2 acting as the oscillator anode. G3 and g5 are screening grids and the signal is applied to g4 via the top cap.
M-OV describe the X42 as having a carbonised bulb and therefore does not require external metallisation.
The Marconi paper brand label.
The classic envelope is 41 mm in diameter and, excluding the B7 base pins, is 103 mm tall.
References: Data-sheet, 1040 & 1043. Type X42 was first introduced in 1936. See also 1936 adverts.

 

Pin Connections
B7
1
2
3
4
5
6
7
tc
g2
g1
g3,g5
h
h
m,k
a
g4

 

Absolute Maximum Operating Conditions
Heptode
Vh
Ah
Va
Vs
Vg
mAa
mAs
gm
4.0
0.6
250
100
-3-145
3.4
2.6
0.49
Thanks to Frank Philipse for supplying the above PDF datasheet.
Updated February 22, 2022.
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