The X145 is a triode heptode mixer. This example is of early B8A base design with a metal skirt, spigot and locating pip. The locating pip was required as the pins were equally spaced around the glass base disc.
The 10C1 was equivalent.
The screen obscures the internal structure.
The construction of the valve is all glass with rod type pins. The skirt contains the locating pip and the spigot would have originally covered the evacuation pip - now at the top. Later production omitted the spigot and finally the metal skirt itself.
The thin glass tube envelope is 20 mm in diameter, and excluding the B8A base pins is 52 mm tall.
References: Data-sheet, Data & 1040. Type X145 was first introduced in 1947. See also1947 adverts.
