The 6F14 is an RF amplifying pentode for operating in a parallel (fixed voltage) environment. Such a device would be used for radio receivers and VHF television.
Mazda used a locating spigot for the B8A base, Mullard moved to a locating pip for the B8A valves.
The control grid copper supports are topped off with a cooling fin. Inside the metal screen can just be seen the three concentric wire grids.
The thin glass tube envelope is 20 mm in diameter and, excluding the B8A base pins and spigot is 55 mm tall.
References: Data-sheet & 1040. Type 6F14 was first introduced in 1948. See also1948 adverts.
