Sieman-Phillips 7308 and JAN Phillips 6922

Tomycy6 is right. For a better understanding and history go to Brent Jessee's site and read what he has to say about the 6922 tubes.

Thanks. All I see on the tube is "D80", 7308/USA and a symbol that doesn't seem to cross-ref to the symbols in the tube codes.

My best guess would be that they were made in the 80's maybe?

JAN stands for Joint Army Navy. Tubes were taken from a standard production run and screened for closer tolerences. Only the tubes that met the military's requirements got the JAN desgination.

The Dutch Phillips company owned several tube makers including Amperex, Mullard, Siemens and Valvo. Tubes were frequently made by one manufacturer and labelled for another.

Tubes were etched, usually near the bottom of the glass, with a code that designated where and when the tube was made. Google Phillips Tube Codes and you can find a pdf file with information about all the various tube codes.