Very few double diode audio output pentode valves were designed.

The valve has a common cathode and the diodes are for signal rectification for detector or AGC service.

The EBL21 is an updated version of this early side contact base design. It is probable that the EBL1 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 classic envelope is 41 mm in diameter and the length excluding the Ct8 base pins, is 120 mm.

 
Pin Connections

Ct8	1	2	3	4	5	6	7	8	tc
	m	h	h	k	a(d1)	a(d2)	g2	a	g1

 
Absolute Maximum Operating Conditions

Pentode	Vh	Ah	Va	Vs	Vg	mAa	mAs	gm	Pout	D
	6.3	1.4	250	250	-6.0	36	4.0	9.5	3.6	10%

Thanks to Frank Philipse for supplying the above datasheet

This exhibit was last updated on 10 June 2007 {find valves by name}