The 20F2 screened RF pentode was designed for use in universal (ie no mains transformer) sets with a series connected heater chain. Mostly in television receivers at RF or as a sync separator.
This exhibit is of the first style of B8B based valves in that it is of all glass construction but also has has a metal skirt with both a locating pip and a long central spigot. Later B8B valves evolved into a locating pip moulded into the glass envelope.
The Mazda logo and Made in England. The locating pip is in the centre of the skirt.
The thin glass tube envelope is 20 mm in diameter and, excluding the B8A base pins, is 54 mm tall.
References: Datasheet, 1040 & 3002. Type 20F2 was first introduced in 1949.
Absolute Maximum Operating Conditions¶
Updated November 10, 2017. shape:thin.glass.tube construction:all.glass type:pentode age:1940.1950 base:b8a heater:200ma pins:8 pin:1.h pin:2.a pin:3.s pin:4.g3 pin:5.g2 pin:6.g1 pin:7.k pin:8.h