[aragon63]

Can someone identify in what year they were made ?  Date codes are F3B, H3B .

 Thx
   

[medium jim]

If you are trying to date code the tubes shown, one shows the EIA Code of 312 (Sylvania) and the date code 5437 (37th week of 1954).

Here's a good source for decoding:

http://www.triodeel.com/eiacode.htm

Jim

[aragon63]

Thanks, Jim !