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W81

Sensibly equivalent to:
7H7 W143 W148
    
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The W81 is a variable μ amplifier pentode. It is a high impedance device with a medium mutual conductance. Variable μ devices are primarily designed for IF and RF amplifiers in radio receivers. The anode current is quite high, this suggests that the device may have been designed for low noise input stages of HF communications receivers as noise performance improves when operated at higher power.
A glass envelope is enclosed by the thin aluminium can.
The wide glass tube envelope is 33 mm in diameter, and excluding the B8B base pins, is 60 mm tall.
Reference: 1040. Type W81 was first introduced in 1947.

 

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
0.3
250
100
-3.6
10
3.2
0.8M
2.8
Updated April 30, 2013.
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