Quote:
Originally Posted by miniman82
It's not a developmental tube, since it has that orange dag in it that makes it a 21AXP22A same as the CTC-5's had. If it is a date code, 9th week of 1963 means the set was run for a good long time. Couldn't have been run for long after it was put in though, since it tests like new.
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I have seen one other example of a code like this on a 21AXP22. It could be a replacement part number that RCA Service Company used.
Another thought is that it may be a RCA Industrial Tube Division code for 21AXP22 type tubes. Back in the day, IIRC RCA had an industrial division that did contract work for the government, military, and industry. RCA even had a computer division. I am sure you have seen RCA vacuum tubes, that were labeled with a number different from the same tube in the consumer division. Often those tubes had a different type of base and an alternate tube number. Perhaps RCA Service Company got 21AXP22 tubes out of the parts warehouse for the industrial division after they were no longer available from the consumer products division parts warehouse. They probably used a different code number in the industrial division so that they could charge big dollars to the government for replacement parts. Sort of like the $1000 toilet seat and the $500 screwdriver, making claim that it was a special "industrial Grade" tube so it cost more.
Maybe it is better than a consumer grade tube. It tests like New, so maybe it was a better quality than the regular consumer division tube.