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W76

Sensibly equivalent to:
12K7GT KTW74M
    
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The W76 variable-mu screened pentode was designed for intermediate frequency amplifiers in superhet type receivers with a series heater chain.
The W76 has a high anode impedance allowing for a high Q in the tuned anode circuit.
The M-OV lozenge with the identification.
The branding to Marconi is by a stick-on paper label. Osram valves would come from the same production line and have a different paper label applied.
The outer perforated cylindrical screen hides most of the internal details.
Looking up from the base the three wire grids can be seen.
The wide glass tube envelope is 28 mm in diameter and excluding the IO Base pins the valve is 89 mm long.
References: Data-sheet, 3002, 1040 & 1043. Type W76 was first introduced in 1945.

 

Pin Connections
IO
1
2
3
4
5
6
7
8
m
h
a
g2
g3
nc
h
k

 

Absolute Maximum Operating Conditions
Pentode
Vh
Ah
Va
Vs
Vg
mAa
mAs
ra
gm
13.0
0.16
175
100
-3
8.5
1.7
0.5M
1.5
Thanks to Frank Philipse for supplying the above PDF datasheet.
Updated August 23, 2020.
shape:wide.glass.tube construction:pinch type:pentode age:1940.1950 base:io pins:8 pin:1.m pin:2.h pin:3.a pin:4.g2 pin:5.g3 pin:6.nc pin:7.h pin:8.k
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