In my stash of tubes I came across a quad of metal tubes I can't identify and I would like some help. The only printed markings are "B-1532", which is printed in Sylvania/Amperex yellow. Also moulded into the pin/keyway surface is "licensed only to extent indicated on carton". Hand written on three of them is " CT-128" or "CT-123", which is written with a red marker. Physically they don't fit any of the outlines shown in my RCA, SYLVANIA, GE, CBS, TELEFUNKEN, AMPEREX, WE, Tung-Sol, or EIMAC tube manuals so I'm stumped. I've also looked at some military cross references and don't see this number. Yes I have a lot of tube manuals and thousands of tubes. They look like 6N7 except they have an extra section between the crimp and the pin/key surface which is 0.595" long, making them 3.648" overall in length. Anybody know what they are, or have a guess as to what they might be?
Thanks, Ron
Thanks, Ron