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7S7

Sensibly equivalent to:
7J7 X148 X81
    
Extras ▼

 

The 7S7 triode heptode was designed for frequency changer use in radio receivers. This exhibit also carries the Type designation of X81(M). The X81 is normally enclosed in an aluminium can.
The 7S7 was also made for mobile use with 12 Volt vehicle batteries for the heater, in this case the valve was called the 14S7.
The grids extend above and below the anode.
The wire support seen on the left is the connection to the triode anode.
The wide glass tube envelope is 29 mm in diameter and, excluding the B8B base pins, is 56 mm tall.
References: Datasheet & 1040. Type 7S7 was first introduced in 1948.

 

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
Heptode
Vh
Ah
Va
Vs
Vg
mAa
mAs
ra
gm
6.3
0.3
250
100
-2
1.8
3.0
1.25M
0.525

 

Absolute Maximum Operating Conditions
Triode
Va
mAa
150
5.0
Thanks to Frank Philipse for supplying the above PDF datasheet.
Updated September 29, 2018.
shape:wide.glass.tube construction:all.glass type:triode.heptode age:1940.1950 base:b8b heater:6.3v pins:8 pin:1.h pin:2.a pin:3.a(t) pin:4.g1(t).g3 pin:5.g2.g4 pin:6.g1 pin:7.k pin:8.h
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