PM2 - early Mullard with paper label, no white infill in groove. Power triode valve for audio output. 2 volt, 200 mA filament. Anode voltage 150 V, grid bias -7 to -13.5 V, mu 7.5 ra 4.4 kOhms. B4 base. Cost 15/- in 1931, equivalent to £117.00 today, using average wages! B4 base.

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