[Amps] Eimac 3-400Z date stamp

[jsb at digistar.com]

hi,

I have a couple 3-400Z tubes but I can't find the date stamp on the glass.
The dome-shaped flashing along the bottom has  1T-833  engraved into it.
Is there any way to derive when these tubes were made from that number?


Thanks,
Jason N1SU