Sometimes you have to get creative with search terms on Craigslist to unearth good deals. Searching for "vintage radio" on SF Bay CL brought up an ad labeled "vintage radio transistor tester". It had several pieces of old test equipment: the mentioned Heathkit FET/transistor tester, as well as an old Eico VTVM, a 1960s benchtop DC voltmeter, and a Heathkit IM-4100 frequency counter. Old Heathkit frequency counters are hard to find, so I called the guy up and set a time to meet. Yesterday I drove to Berkeley to meet the guy. He is a Black blues musician whose grandfather was a ham for decades. It was unusual, but not unheard of, for a Black person to be into electronics and hamming, and CA was more liberal and open to stuff like that. The guy said that his grandpa left behind a bunch of radios and other detritus of a life in electronics, and though he'd sold the radios he admitted that he had zero clue what all the benchtop test equipment was for. I got the counter for $20. It appears to work well. Looks like the original owner cared for his stuff. The back. The owner had chopped off the ground peg on the AC plug, apparently he lived in a very old house that lacked modern AC plugs. I will have to replace the cord. What the heck is this 12vDC plug? Another Heathkit semi-proprietary interface? The jacks too. Not quite sure what these are. So, I will have to hit Google and see if I can find a copy of the manual. As I said, the AC cord needs replacing due to the ground peg being chopped off.