Quote:
Originally Posted by Carth
Us old uns remember turning the TV or Radio on and waiting 5 minutes for the valves to warm up  |
Our earliest valve TV had 2 switches: the first turned on the heating elements to warm the valves, the second, operated a couple of minutes later, turned on the HT (High Tension voltages). This was to prevent cathode-stripping which ruined thermionic valves very quickly.
As I joined the RAF, thermionic valves were starting to be replaced by discrete transistors. A few years later we were up to our eyes in Integrated Circuits and logic boards.