"The basic, domestic quality thermionic tubes have codes for a projected life span of either 1500 (6Н3П-Е) or only 500 hours (6Н3П). Many were used and then stored for over 50 years, quality stamps may have been accidentally altered, so life expectancy may be questionable, both for the tubes and for me!"
I love the idea of an expiration date, or at least an ever-present need for repair. It emphasizes the idea that the computer is a machine, subject to the constraints of the physical world. There's something charming about that.
I restore a lot of 50s era tube radio equipment. The tubes are suprisingly robust!
I'm surprised at how many times _resistors_ go bad, and of course we all know that capacitors fail. But more often than not, all the tubes in a typical 5 tube AM radio I find are working.
Radio Shacks¹ used to have a tube tester machine in them.² I was always impressed that there was such a finite universe of tubes that a single machine could test all of them.
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1. For the kids, this was a store that sold various electric gizmos including radios and circuit components, then later computer and televisions.
2. I think they may have also been present in hardware stores as well.
I remember tube testers at grocery stores when I was a kid. I'd go with my dad to test tubes from our TV set, and buy replacements for burned out ones.
I love the idea of an expiration date, or at least an ever-present need for repair. It emphasizes the idea that the computer is a machine, subject to the constraints of the physical world. There's something charming about that.