Early 1970's RCA portable.

[Jon A.]

Originally Posted by zeno

Eliminating the hot-cold cycle was sold as longer tube life BUT
the constant heat baked the PCB's & dried up the sets so much
it shortend the life of the set. Nothin worse than an all tube
instant on set with high miles.
Later solid state sets probably benefited from it, you never see
a bad CRT in a flat chassis Zenith. They also came out with
fast warm-up cathodes. And yes it can be defeated quite easily
most the time.

73 Zeno

I was going to eventually ask how to defeat it in my flatty, but best to leave it alone I guess.