The EL12Spec was made by the Czechoslovakian manufacturer Tesla. It is an Audio output pentode and the naming convention of EL12 follows the Philips/Mullard principles. So we also know that this valve has a 6.3 Volt heater.
The Footless base is a continental that is rarely seen in UK made equipment.
The classic envelope is 44 mm in diameter and, excluding the Footless base pins, is 117 mm tall.
Reference: Datasheet. Type EL12Spec was first introduced in 1940.
Absolute Maximum Operating Conditions¶
Updated February 22, 2013. shape:classic construction:pinch type:pentode age:1940.1950 base:footless heater:6.3v pins:8 pin:1.- pin:2.g1 pin:3.k.g3 pin:4.- pin:5.h pin:6.h pin:7.- pin:8.g2 pin:tc.a