On Jun 2, 12:39*pm, "William Sommerwerck"
wrote:
"Smarty" *wrote in ...
I recall vaguely that the rare earth material from which red phosphors
were created was comparatively inefficient, unstable, and expensive.
I think it might have been ytrium but I may have the name wrong.
Zenith and others many decades ago proudly introduced newer and
more advanced red phosphors but I would not be surprised that they
wore out faster.

This broad error about red phosphors has been repeated many times in this
group. Many people here grew up during the introduction of rare-earth
phosphors, so it's hard t understand why the error persists.

The original red phosphor had low output and turned orange-ish when pushed.
The rare-earth red phosphor -- introduced in the mid-60s (I think) -- had
greater output and more-consistent hue. It might have deteriorated faster (I
don't know), but //it// was the advanced phosphor -- not the phosphor that
preceded it.

I specifically remember a radio program sponsored by Sylvania that promoted
these new phosphors as bringing color TV "out of the dark ages".

Even after the introduction of the rare-earth phosphors, the red
phosphors were less efficient and the red electron gun still had to
put out more electrons than the green or blue guns and so the red gun
trended to poop out sooner than the green or blue guns.