1st letter |
construction |
1 |
half-wave rectifiers |
2 |
diode |
3 |
triode, output |
4 |
triode, high-mu |
5 |
tetrode, straight |
6 |
tetrode, vari-mu |
7 |
power or video pentode |
8 |
pentode, R.F. straight |
9 |
pentode, R.F. vari-mu |
10 |
duodiode |
11 |
duodiode-triode |
12 |
duodiode-pentode (AF) |
13 |
duotriode, high-mu |
14 |
duotriode for class B output |
15 |
heptode |
16 |
triode for DC coupled outputs |
17 |
duodiode-pentode (RF) |
18 |
triode-pentode |
19 |
? |
20 |
triode-hexode/heptode |
|
|
next letter |
heater |
A |
3.6-4.4 V indirectly |
B |
2 V directly |
C |
other directly then 2 or 4 V |
D |
all other heater ratings indirectly heated other then 4 V |