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X31

Sensibly equivalent to:
CV3821
See also:
Osram X41 & X31 Advert - Some Important British Valves - M-OV X41 and D41 - Applications of the new valves 1935
    
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This X31 is a metallised triode hexode frequency changer. The X31 was designed with a heater for universal mains (AC/DC sets) whereas the X41 was the same valve but designed for AC mains receivers.
The X31 designation was later re-used for a miniature valve. in this exhibit the printing has all but been lost from the metallising and it was difficult to identify it without strong light and a glass.
The classic envelope is 42 mm in diameter and, excluding the B7 base pins, is 117 mm tall.
References: Data-sheet & 1043. Type X31 was first introduced in 1935. See also 1935 adverts.

 

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

 

Absolute Maximum Operating Conditions
Hexode
Vh
Ah
Va
Vs
Vg
gm
13.0
0.3
250
80
-1.5
0.55

 

Absolute Maximum Operating Conditions
Triode
Va
150
Thanks to Frank Philipse for supplying the above PDF datasheet.
Updated January 04, 2024.
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