The American Government code of VT-209 is also the commercial 12SG7. It is a 12.6 Volt version of the 6SG7 semi-vari μ pentode and except for the heater they are identical.
When Sylvania introduced the Loctal base in 1941, the 14H7 had the same characteristics as the 12SG7 and the 7H7 matched the 6SG7.
The RCA logo.
As expected this valve was made in the USA.
The thin metal tube envelope is 25 mm diameter, and excluding the IO base pins, is 51 mm tall.
References: Data-sheet, 1040 & 1043. Type 12SG7 was first introduced in 1940. See also1940 adverts.
