Sensibly equivalent¶ to:
55B/400A 5894/C178A 5894A 5894 CV2797 TT25
The QQV06-40A is an excellent example of good design. Within the envelope are two beam tetrodes with a maximum anode dissipation of 40 W.
Following the European pattern, a central flat cathode is surrounded by a split control grid (one half per valve), a common screen grid is wound next. The two beam forming plates can be seen either side of the central assembly. The anodes are finned for good heat dissipation and clearly separated from the central structures, the anodes are brought out to pin like top caps.
The heater is centre tapped to allow for 12.6 or 6.3 volt operation.
In use the designer would take care to keep the grid circuitry below the chassis with the anodes being connected to circuits remote from the input. This way undesirable feedback could be avoided.
The European design of internal capacitors for neutralisation can be seen at the top of the valve. Such neutralisation prevented parasitic oscillations during operation in a well designed layout.
The wide glass tube envelope is 44 mm in diameter and, excluding the B7A base pins, is 72 mm tall.
References: Datasheet & 1040.
Absolute Maximum Operating Conditions¶
Updated August 30, 2018. shape:wide.glass.tube construction:all.glass type:double.beam.tetrode age:1950.1960 base:b7a heater:6.3v pins:7 pin:1.h pin:2.g1(2) pin:3.g2 pin:4.k.bp pin:5.hct pin:6.g1 pin:7.h pin:tc.a pin:tc.a(2)