The Mullard EL84 is a classic audio beam tetrode valve, immortalised in the 1950s 5-10 design for an audio amplifier. The UL84 was designed with a 100 mA heater, for use in universal voltage environments. Our exhibit carries the Mullard logo but was not of UK manufacture.

On a DC mains supply no transformer to increase the HT voltage is possible so the UL84 is designed to operate at lower anode voltages and increased anode current.

The UL84 can be used for push pull operation but the normal service would have been in single ended applications.

The thin glass tube envelope is 20 mm in diameter and excluding the B9A base pins the valve is 68 mm long.

 
Pin Connections

B9A	1	2	3	4	5	6	7	8	9
	ic	g1	k,g3	h	h	ic	a	ic	g2

 
Absolute Maximum Operating Conditions

Beam Tetrode	Vh	Ah	Va	Vs	Vg	mAa	mAs	ra	gm	Pdiss	Pout	D
	45	0.1	170	170	-12.5	70	5	230k	10	12.0W	5.2	10%

Thanks to Frank Philipse for supplying the above datasheet

This exhibit was last updated on 12 June 2007 {find valves by name}