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7S7

Sensibly equivalent to:
7J7 X148 X81
See also:
7S7 Advert, November 1948
    
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The 7S7 triode heptode was designed for frequency changer use in radio receivers. 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 Brimar identification is clear but the coating on the inside of the envelope partly obscures the details of the valve's construction. Close inspection under strong light reveals a single cathode and two valve sections mounted vertically.
The dome allows some view of the construction. The top section is the triode.
The wide glass tube envelope is 28 mm in diameter and, excluding the B8B base pins, is 57 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 January 31, 2013.
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