Quote:
Originally Posted by crtfool
Slightly off topic - what does the letters in the different tubes mean - CYP, AXP, FBP, etc. Just wondering - never really paid attention when I was dealing with CRT sets years ago.
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AFAIK, they were simply assigned in sequential order, like non-vanity amateur radio call signs.
In CRTs, the diagonal size replaces the filament voltage at the prefix of the tube type. The type of phosphor replaces the numeral for the number of connections at the suffix. P4 phosphor is medium-persistence white phosphor (far more suitable for a black-and-white TV then, say, the long-persistence green P1), whereas P22 is an array of red, blue and green phosphors (in English, a color tube).
It does seem they ran one sequence in each size to be shared with color and B&W (e.g, there is no 15GP4 nor any 21DEP22)
Still, there are inconsistencies. Why is there a 30BP4, but no 30AP4. The 1828P22 is, of course, out of left field, with no letter before the P, and hopefully not 1828" diagonal (or our winning bidder will pay through the nose for shipping!).
These inconsistencies are found in receiving tubes, too. The 1DN5 seems to have jumped the sequence by a wide margin. At an antique radio show last winter, I met someone with a large supply of 6R-SP22 tubes - they weren't even picture tubes! (by outward appearance, they resembled type 6CL6).
Another use of "letters in place of numbers" sequential identification is found in projection lamps. Looking at most of the bulbs, the oldest types are "C** (e.g. the quite old CDS from the 1940's and newer CZX from the 1950's), through the D**, E** and F** (like FCS that is only seen in equipment from the late 1970's and later). Inconsistencies occur here, too, with some quite new designs of bulb being C** or even B**.