1st letter |
heater |
A |
0.06-0.10 A |
B |
0.10-0.20 A |
C |
0.20-0.40 A |
D |
0.40-0.70 A |
E |
0.70-1.25 A |
F |
> 1.25 A |
|
|
next number(s) |
heater |
x |
heater voltage < 10 V |
xx |
heater voltage >= 10V |
|
|
last 2 numbers |
construction |
41, 51... |
tetrode with spacecharge grid |
42, 52... |
tetrode with screen grid |
43, 53... |
power pentode
|
44, 54... |
triode with diode or tetrode with diode |
45, 55... |
RF tetrode with variable gain |
46, 56... |
RF pentode |
47, 57... |
RF pentode with variable gain |
48, 58... |
hexode frequency changer |
49, 59... |
hexode with variable gain |
xx |
amplification factor for triodes |
|
|
last letter |
(optional) |
H |
|
N |
New, later version
|
S |
Series connection allowed
|
T |
|