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The VU72 was the pre-CV RAF code for the commercial mercury vapour rectifier type GU50. The latter exhibit has a clearer glass envelope and so the internal structure is easier to see.

The maximum reservoir capacitor is 4 µF. The filament is a twin horseshoe of corrugated tape. The anode is a short dustbin lid connected to, and supported by the top cap.

One half of the filament has broken off and can be seen on the left side of the image. As the two filament halves are connected in parallel, there is still continuity.

The classic envelope is 47 mm in diameter and, excluding the B4 base pins, is 123 mm tall.

References: Data-sheet & ¹⁰⁴⁰. Type VU72 was first introduced in 1940. See also 1940 adverts.

Pin Connections

Absolute Maximum Operating Conditions^¶

PDF scanned from an original document held by the museum