Introduction
The European way of marking valves differ somewhat from the
American way. The American way of marking valves is basically completely arbitrary. There
are a few exceptions for example the marking 12AX7 tells you that the valve has a 12.6 V
series heater voltage.
The European way of marking valves is a bit more elaborate and
gives you far more information about the function and design of the valve.
The anatomy of letters
First letter
The first letter denotes the heater voltage/current:
A = 4V
E = 6.3V
D = 1.4V
G = 4V
H = 150 mA series heater
K = 2V battery
P = 300 mA series heater
U = 100 mA series heater
V = 50 mA series heater
Q = Output tetrode for transmitter usage |
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Second letter
The second letter from left denotes the first valve function:
A = Diode
B = Double diode
C = Triode
F = Pentode for small-signal amplification
H = Heptode
L = Pentode for power amplification
M = Magic Eye
Y = Half-wave rectifier
Z = Full-wave rectifier
Third letter
The second letter from left denotes the second valve function:
A = Diode
B = Double diode
C = Triode
F = Pentode for small-signal amplification
H = Heptode
L = Pentode for power amplification
M = Magic Eye
Y = Half-wave rectifier
Z = Full-wave rectifier
Additional letters
Additional letters denotes additional valve functions. |