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The Bentley Acoustic Company were importers and retailers. The interesting aspect of this valve is the window in the anode half way up so that the cathode tube is revealed. The coating is seen in the picture but only under a glass can the clearance between anode and cathode be seen. In this valve it is about 1 mm. At the top of the cathode tube the plane nickel can be seen with a single hairpin of heater within. This heater looks ribbed, thus indicating that the Tungsten wire has been coiled before being coated with insulation and folded prior to firing.

See EF80 for details.

The PY80 is a half wave rectifier for television HT systems.

The maximum reservoir capacitor is 60 µF, and the minimum series resistance has to be 45 Ohms.

The thin glass tube envelope is 20 mm in diameter, and excluding the B9A base pins, is 71 mm tall.

References: Data-sheet, ³⁰⁰² & ¹⁰⁴⁰. Type PY82 was first introduced in 1951. See also 1951 adverts.

Pin Connections

Absolute Maximum Operating Conditions^¶

Thanks to Frank Philipse for supplying the above PDF datasheet.