The EBL1 is one of very few double diode audio output pentode valves were designed and was released in 1938. The EBL31 is electrically the same valve but fitted with an IO base cap and was released in 1940.
The valve has a common cathode and was intended as a single valve detector and audio stage driving the output transformer (7,000 Ohm primary) and loudspeaker. It would have needed considerable drive at intermediate frequency and the output pentode is of high gain.
The main market for this type of valve was simple receivers for local station reception.
The EBL21 is an updated version.
The classic envelope is 41 mm in diameter and the length excluding the Ct8 base pins, is 120 mm.
References: Datasheet & 1043. Type EBL1 was first introduced in 1938.
Absolute Maximum Operating Conditions¶
Updated February 11, 2014.