1st number | heater |
0 | no heater |
1 | 0.1 - 2.0 V |
2 | 2.1 - 2.9 V |
3 | 3.0 - 3.9 V |
n | n.0 - n.9 V |
next letter(s) | serial code |
final number | number of elements in the tube |
final letter(s) | (optional) |
A | controlled heater warmup time |
B | improved ratings/performance |
C | ditto |
G | glass bulb |
GT | glass tubular |
W | ruggedised version |
X | low loss ceramic base |
Y | low loss phenolic base |