UL84=45B5 Telefunken Diamond Bottom NOS 1960

Vfil=45V

Pentode

Vplate max = 170V

The Mullard EL84 is a classic audio pentode 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 and thus with limited HT available. 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 such as radios and record players.

The PL84 is another variant but with a 300 mA heater. The main application was TV frame output but audio was also possible.

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

References: Datasheet. Type UL84 was first introduced in 1955.