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The QQE04-20 is a dual transmitting beam tetrode. The design is of the American type with two separate valve electrode systems sealed into the single envelope. The oval cylinder anodes enclose the beam plates, grids and heater cathode assembly.

Originally the 832 envelope was rounded below the central band but this Mullard implementation has the later envelope with the flatter base.

This type of construction usually required external capacitors to neutralise parasitic oscillations. These capacitors normally taking the form of vertical wires alongside the envelope.

This valve was obsolete by the start of the 1960s replaced by the QQV03-20 orQQV06-40A varieties.

The wide glass tube envelope is 50 mm in diameter and, excluding the B7A base pins, is 51 mm tall.

References: Data-sheet. Type QQE04-20 was first introduced in 1957. See also 1957 adverts.

Pin Connections

Absolute Maximum Operating Conditions^¶

Thanks to Frank Philipse for supplying the above PDF datasheet.