The early 1950s ECL80 is a triode, output pentode for audio use. The heater at 6.3 Volts and 300 mA makes this valve suitable for equipment with mains transformers and heater chains across the domestic mains.

The ECL80 is a low power device with the triode feeding the pentode for a compact single end audio stage.

Mullard describe the ECL80 as primarily designed for use in television receivers (VHF 405 line models) with the triode as a frame blocking oscillator and the pentode as a frame output valve. Other applications include the use of the triode as a line blocking oscillator, AF voltage amplifier or in multivibrator circuits and the operation of the pentode as an audio output valve or a synchronising pulse separator. This valve was also used in low cost record players with high output crystal pick-ups, normally with a metal rectifier. The latter being an early solid state device.

The ECL80 was not without faults in use and the above article gives details.

The lower electrode structure is the beam tetrode, the triode is a 5 mm structure at the top of the valve.

The copper grid supports have cooling fins spot welded on.

The thin glass tube envelope is 20 mm in diameter and, excluding the B9A base pins, is 58 mm tall.

References: Datasheet & ¹⁰⁴⁰. Type ECL80 was first introduced^¶ in 1952.

 
Pin Connections

B9A	1	2	3	4	5	6	7	8	9
	a(t)	g1(t)	k,s	h	h	a	g3	g2	g1

 
Absolute Maximum Operating Conditions^¶

Pentode	Vh	Ah	Va	Vs	Vg	mAa	mAs	ra	gm
	6.3	0.3	200	200	-8	17.5	3.3	25k	5

Thanks to Frank Philipse for supplying the above PDF datasheet

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