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12AT7

Sensibly equivalent to:
6060 B152 B309 CV455 E2157 ECC81
See also:
Valves and their Habits - Pin Compatible Double Triodes - Double Triodes in Audio Amplifiers Advert - Noval Based Valves for Audio Amplifiers Advert
    
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The Mullard ECC81 was designed for RF use and is of medium impedance in this exhibit the first Type designation on the glass is 12AT7, the American designation.
The 12AT7 also makes an excellent phase splitter in modern audio applications and is regarded as a better valve for new designs rather than the purpose designed high gain 12AX7that has a small grid drive range.
This exhibit is British Made and carries the older Mullard logo as well as the BVA logo.
The twin sections. The triode anode is a small rectangular box with an extended flange for greater head dissipation.
The thin glass tube envelope is 20 mm in diameter and excluding B9A base pins the length is 49 mm.
References: Datasheet & 1040. Type 12AT7 was first introduced in 1947.

 

Pin Connections
B9A
1
2
3
4
5
6
7
8
9
a(2)
g1(2)
k(2)
h
h
a(1)
g1(1)
k(1)
hct

 

Absolute Maximum Operating Conditions
Triode
Vh
Ah
Va
Vg
mAa
ra
gm
6.3
0.3
250
-2.0
10.0
10,000
5.5
Thanks to Frank Philipse for supplying the above PDF datasheet.
Updated September 26, 2019.
shape:thin.glass.tube construction:all.glass type:double.triode age:1950.1960 base:b9a heater:6.3v pins:9 pin:1.a(2) pin:2.g1(2) pin:3.k(2) pin:4.h pin:5.h pin:6.a(1) pin:7.g1(1) pin:8.k(1) pin:9.hct
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