08-16-2009, 11:29 AM
The number is the last digit of the year. Letters are months: C is January, B is October and H is February. After September 1935 the month codes changed: B is February, C is March, H is August.
In either case it seems odd to have dates so far apart (I'm quite sure Philco did not stockpile tubes for months).
These are Sylvania codes, and it's possible Philco bought tubes from someone else, which would have different codes.
In either case it seems odd to have dates so far apart (I'm quite sure Philco did not stockpile tubes for months).
These are Sylvania codes, and it's possible Philco bought tubes from someone else, which would have different codes.
![[-]](https://philcoradio.com/phorum/images/bootbb/collapse.png "[-]")
