In the early 70s many poor starving young engineers got by watching tired old ctc-4s and 5s (and a few old Westinghouse sets as well).
The tuners on the 4s needed much attention. One lunch hour, my manager took an extended break to pick up a couple of tuners that a local re-builder had just finished, while I covered for him. About 12:30 I got a call "Hey jr, I am down at the tuner shop and he has one of those big OLD RCAs with the little screen that you are looking for...he wants 50 bucks for it".
We settled on 35$ and my manager loaded it up and delivered it to my house... Can't get management like that today!!
The 4s and 5s (and 21" round screen Westinghouse sets)*... those mostly just got junked when it was not economical to keep them up... there were plenty more out there for cheap viewing.
*One ex-Westinghouse engineer hung on to a 22" Westinghouse rectangular screen set until the early 80s, when he moved, and gave it to me.
jr