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.
See also EL12N for a later implementation of the basic specification.
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: Data-sheet. Type EL12Spec was first introduced in 1940. See also 1940 adverts.
Absolute Maximum Operating Conditions¶
Updated January 04, 2022.