This was years ago. Dad and his friend are now sending radio waves from somewhere else. I wanted to get into Ham radio and ended up playing on the early CB's. That was when call letters and being polite was in.
I remember them well. My father said he never trusted them as they were designed to sell tubes, so every tube tested would show as "bad."
Here's a photo of one actually IN a drug store ready to be used. It's at the far left. This is my uncle's store, and the photo was taken some time in the 1960s.
The tubes we tested were not all bad. There's a department of government, here, which certifies weights, measures etc... They make sure that, for example, gasoline pumps accurately display exactly what gets pumped or air guages to certify that your tires are filled with the proper pressure. They also inspect scales at weekend outdoor markets, as well as those in supermarkets. If those tube testers were tampered with, sooner or later the proprieter would get into trouble. Especially, if he had replacements on the shelf. What your dad should have done is to test a new tube, in the machine, and go to the cops, if it fed back defective. In electronics, you have a thin margin between good and bad, regarding resistors, tubes, capacitors etc. There is no such thing as one third or one half good. If it's, taking a wild guess, 5% gone, it's not fit for service
We have that here, too, for gasoline pumps, weight scales in grocery stores, and things like that. I don't think such a thing existed for in-store tube testers, but I don't know for sure. I'm not saying that every drugstore tube tester was fixed to make all tubes look bad. I'm just saying that that was my father's opinion. As a 10-year-old tagging along, what did I know?
Actually have 3 of these in red, yellow and blue. It's called a Panasonic "TNT" player. You hit the plunger to change tracks. (It doesn't change by it's self) Plus I have a "Lloyds" in white which has a better speaker. You tube shows how to change out the crappy speaker in the Panasonic for a Macintosh modern high quality speaker. Still not stereo though, and I hate modifying a vintage piece like this so they stay as manufactured.
Too bad, those Queen tapes don't explode, when the plunger gets hit. Why can't annoying wanna be entertainers take their stuff with them, when they bite the dust. There are too many Queens, in those stacks, and not enough Z Z Tops, Led Zepplins and Allman Bros
Just a fraction of my collection kid. Over 1000 tapes in the collection including what you mention. Notice "Jet"? I made that from the CD. Also have tapes of the Safari's and Dick Dale who never issued a cart. But, I do like Queen. Can't deny that. Do you have any "Traffic" in your collection? "Faces"? "Badfinger"? "Dr. John? I got all the good stuff, most of it in the car. So, float off dude and come back when you grow up.