Quote:
Originally Posted by etype2
Very interesting, so now I have to find a quad machine. :-)
In a 1954 publication, Westinghouse claims the red phosphor in the 15GP22 had a “slow persistence causing fuzzy images”. Would this be one one of the reasons phosphors were changed? I know brightness as you say was an issue.
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I haven't noticed an overly long persistence in the CT-100s I've seen, but I wasn't looking for it - interesting. The major reason for changing the red phosphor was for greater efficiency and therfore picture brightness, since it required much more current than the green or blue. An interesting note is that subsequent red phosphors were close in color to the original, except for the zinc cadmium sulfide in the all-sulfide tubes, which turned more orange than the original at high currents.
Edit: is it possible this comment refers to experimental tubes that preceded the production version of the 15GP22?
I have read that some early prototype tubes had a red phosphor that required using a color filter over the face, making for a really dim picture; not sure about the persistence.