I have a number of 1980s-vintage Technics AM/FM radios around the house. All of these use an RCA-style plug labeled "REMOTE", and I believe are intended to be u

I have a number of 1980s-vintage Technics AM/FM radios around the house. All of these use an RCA-style plug labeled "REMOTE", and I believe are intended to be used for hooking a Technics radio up to a Technics stereo amplifier. Sadly, the manuals for the tuners I do have are mostly mum on what it does - they're like bad API documentation saying `remote: the remote input` or such. I have a passing interest in doing something with this on all of the tuners, but all I've really managed to reliably do is get them to tune to exactly 1000kHz AM if I short the center to ground.