[dhosek]

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.

⸻

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.

[euroderf]

There was a tube tester in our town's main pharmacy.

So in principle you could pull the main tubes from (say) your TV and have at it.

[themadturk]

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.

[quercusa]

There's a HeathKit one up on Ebay now: 'Heathkit TC-3 Tube Tester'