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RE: Sylvania GB 5751

Posted by Mechans on February 16, 2012 at 13:40:45:
TMGP 5751 GB by Sylvania I understand were produced circa. 1960. The 3 mica examples being earlier ca. late 50s and the 2 mica versions almost universally represented as early 60s.
I have no absolute proof or intimate knowledge of Sylvanias product releases. I only know what I have read here and elsewhere over the past decade or so, in this hobby. In addition, the dated Sylvania 5751s tubes that I own, bear this out, based mainly on packing, such as dates on the military JHS boxes. Triples are invariably 50s, in my collection but I am sure that some might have snuck under the wire and were produced slightly later. Some argue that the construction is definitive that is if it is TM it is 50s and DM that means 60s.
Sorry about the imprecision, but a recent request for "documented knowledge" got me thinking about some of my own preconceptions.