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7B7

Sensibly equivalent to:
CV522 W149
See also:
American Loctal Valves
    
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The 7B7 is a high impedance variable μ amplifier pentode. It was probably designed for IF amplifier use, with a tuned anode circuit.
It is interesting to ask who made the valve. We believe that it is not Cossor as labelled. Construction details are typically American and we have seen Cossor-labelled valves of this vintage (c. 1950) clearly marked 'British Made' (as here) and (on the other side) 'made in USA'. Similar-looking valves were also factored under several other 'big-name' labels around this time.
The wide glass tube envelope is 27 mm in diameter and, excluding the B8B base pins, is 55 mm tall.
References: Private communication, datasheet & 1040.

 

Pin Connections
B8B
1
2
3
4
5
6
7
8
h
a
g2
g3
s
g1
k
h

 

Absolute Maximum Operating Conditions
Pentode
Vh
Ah
Va
Vs
Vg
mAa
mAs
ra
gm
6.3
0.15
250
100
-3
8.5
1.7
0.75M
1.75
Thanks to Frank Philipse for supplying the above PDF datasheet.
Updated August 24, 2015.
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