VR22

VR22 is a battery triode used for audio output. Service sources link it to the later common designation CV1022 and the Cossor 220PA family, identified as prototype in the CV1022 military specification. The VR prefix belongs to RAF nomenclature predating the CV system. Retained descriptions give about 0.18 W output, or 180 mW: modest power to be understood in the context of the battery receivers for which the type was intended. The service correspondence is documented; other reference-book equivalents must not automatically be extended to every construction detail or circuit.

The directly heated filament nominally requires 2 V at 0.2 A. Period arrangements described by our sources use an accumulator for the filament and a dry battery for the anode, serving separate functions. The B4 base carries anode on pin 1, grid on 2, negative filament on 3 and positive filament on 4. The filament itself is the cathode, rather than a separately heated element. The CV1022 document specifies an unmetallized glass envelope.

Ministry of Supply specification MAP/CV1022, Issue 7 of 20 January 1949, gives 150 V maximum anode voltage. It lists 4 mA/V transconductance, amplification factor 16 and 4000 Ω anode resistance, but the note ties all three to 100 V anode voltage and 0 V grid. The 10 mA average anode current instead refers to 150 V and −4.5 V bias; the stated optimum load is 9000 Ω. These conditions must not be merged into one operating point. Acceptance testing is separate too: page two uses a 1.8 V filament, not nominal 2 V, and at 150 V anode and −6 V grid permits 3.5–7 mA anode current.

Photographs add construction details absent from numerical tables. One specimen has a wide but shallow anode, described as about 3.5 mm front to back. Above the main mica, a second mica supports filament-tension springs; spacers attach to the grid supports through small spot-welded metal strips. The balloon envelope and differing specimen dimensions also show that one designation can occur with different physical details. These observations describe those specimens, without assigning identical internals or a single manufacturer to every VR22.