The EF13 is a continental valve that was not used in the UK. It is a low noise RF pentode. It and similar constructed valves were used in German domestic radios during WWII.
The wide metal envelope is 34 mm in diameter and, excluding the Footless base pins, is 35 mm tall.
References: Data-sheet & 1040. Type EF13 was first introduced in 1938.
Absolute Maximum Operating Conditions¶
Updated December03, 2012. shape:wide.metal.tube construction:glass.disc type:pentode age:1930.1940 base:footless heater:6.3v pins:8 pin:1.g2 pin:2.g1 pin:3.k.m pin:4.- pin:5.h pin:6.h pin:7.g3 pin:8.a