When I was a kid we had cable and I tried connecting it to a stereo receiver. There were a couple of interesting things... they deliberately rebroadcast the popular stations on different frequencies so that there wouldn't be multipath between the cable signal and the over-the-air signal. Also, there was one station that was just a constantly repeating two-tone beep. I believe that they used that signal to sniff out illegal cable connections. The cable company employees could just tune a portable FM radio to that frequency and check for the signal coming from a property that was not paying for cable service.
I remember those Jerrold boxes, I also remember the
Hamlin boxes with the big slider for channels 2-58. They had a primitive remote control system where the channel selector was tethered to the actual cable box by a long cord. When I was growing up we had the Oak box with a single knob for channel selection (up to channel 36). If you wanted premium channels you had to pay a monthly charge for the
Zenith SSAVI box with remote.