Quote:
Originally Posted by Electronic M
The face of any color tube is attached to the cone fairly late in the manufacturing process because the shadow mask has to be installed and before that the screen has to be coated in phosphor....Neither of which is practical with the screen bonded to the cone. It would be like building a ship in a bottle. to metal and metal to glass bonds of the rings.
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You know, it is always easier to see someone else's mistake (RCA) than one you (CBS) made. I had always assumed that Goldmark's Laboratory made the first 15HP22's the RCA way and by doing so, quickly realized that there was a better way. However, looking at the patent, we can see that it was filed June 1, 1953 (and granted Sept 28, 1954), so Dave's April 24, 1954 tube is obviously manufactured well after the patent application.
http://www.freepatentsonline.com/2690518.pdf
The "engineering sample" notation may also have been for legal reasons to protect the CBS patent.
This difference probably explains why even though the 15GP22 and 15HP22 were mostly interchangeable, they got a new tube number.
This patent expired in 1971 and CBS thanked Goldmark, by shutting down his Laboratory in 1972.
James