Topic: Early TV museum, USA
This is a fascinating tour of a USA museum of TV cameras and receivers, from the beginnings of TV capability.
About 25 minutes, so take your time viewing it!
https://www.youtube.com/watch?v=YqGaEM9sjVg
It doesn't show much, if any, European TV equipment, and so shows colour wheels rather than PAL.
It also demonstrates that USA companies were working on TV during WW2, and actually dwarfing UK efforts in that direction.