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Original Message

RE: E188CC identification

Posted by beto1 on December 25, 2020 at 08:45:43:

OK, find more information specific to Mullard here: https://mullard.org/blogs/news/mullard-valve-etched-codes-how-to-interpret-them
So, R2F1 must be:
R= Mullard, Mitcham
2=1952 or 1962 or 1972 (The second character gives the year of manufacture with decade differentiation being by number of characters and logo shape. and If its a 4 character code, the valve was produced post 1960, so reduced to 1962 or 1972, no logo)
1=week 1
but this would contradict what is written in the first rectangle, 7501, which according to other publications, such as the one I quoted in the first post, would mean, January 1975