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X81

Sensibly equivalent to:
7S7 X148
See also:
Olympia Show 1947
    
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The X81 is a triode hexode mixer for use in communications receivers. The triode oscillator is designed to produce 10 volts pk-pk to drive the hexode mixer. The all glass envelope is protected by an all encompassing aluminium screening can that also serves to hold the spigot carrying base in place.
See also X81 where the screening can has been removed.
The Marconi paper label.
The wide glass tube envelope is 33 mm in diameter, and excluding the B8B base pins is 59 mm tall.
Reference: 1040. Type X81 was first introduced in 1947. See also 1947 adverts.

 

Pin Connections
B8B
1
2
3
4
5
6
7
8
h
a
a(t)
g1(t),g3
g2,g4
g1
k
h

 

Absolute Maximum Operating Conditions
Hexode
Vh
Ah
Va
Vs
Vg
mAa
mAs
ra
gm
6.3
0.3
250
100
-2.0
3.0
2.4
1.0M
0.65

 

Absolute Maximum Operating Conditions
Triode
Va
Vg
mAa
100
-
3.6
Updated August 26, 2018.
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