It’s a Hickock 600 tube tester. It was received from a fellow ham who had more than one, and took pity on me.
Little better view of the control panel:
It’s in pretty good condition, and while it’s not the most accurate tester ever made, it’ll help me to identify good tubes from bad ones, and that’s most of what I’m looking for.
Now to do my fellow ham a good turn or two.