The 7Q7 is a heptode or pentagrid converter for use as a mixer or frequency changer in broadcast receivers. The design is essentially the Octal 6AS7GT redesigned for the Loctal base that was introduced by Sylvania for use in car radios in 1939.
The main image shows the Sylvania name and the locating bump on the metal skirt. The base spigot has a key to guide the valve into the holder and the depression by the tip is where the spring on the base locks onto the spigot.
The internal coating hides the inner structure.
The dome carries on the outside the 7Q7 Type designation.
The wide glass tube envelope is 29 mm in diameter and, excluding the B8B base pins, is 55 mm tall.
References: Data-sheet & Data. Type 7Q7 was first introduced in 1940. See also1940 adverts.
