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Old 04-24-2017, 01:33 AM
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miniman82 miniman82 is offline
First Light: 1952-2011
 
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Location: Great Mills, MD
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Quote:
Originally Posted by benman94 View Post
I was just giving that as an example of a set that used R-Y/B-Y. Westinghouse did with their 15 incher. I think GE used R-Y/B-Y. I just don't see the reasoning behind the X/Z when R-Y/B-Y worked.
Keep in mind that just because that's what they chose to call it, that doesn't mean that's what it is strictly speaking. Most of the time the demodulator is angularly close to the actual axes, but not exactly. I think I read somewhere the slight offset reduced crosstalk or noise or something, and wayne is correct that certain things had to change to accommodate the CRT being driven. The sulfide tube mentioned is the best example, since the phosphors used weren't exactly....right for direct R/B demod. Everything aside from the first I/Q chassis was designed with cost savings in mind, which is why we got the tube saving CTC-4 with high level demod.

Most of the RCA books mention that in actual operation viewers couldn't tell the difference between I/Q and other methods anyway, so the cost wasn't justified. Calling later schemes X and Z seems more or less arbitrary, but it was probably that way on purpose. X and Z are not defined in the chroma chart, so the actual demod angles can be whatever you want them to be in practice without being wed to a defined number. Sometimes the angles are called out in literature, sometimes not. Only way to really know for sure is to measure.
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