NU4 rectifier

This valve measures 255x120mm overall.

This valve was discovered along with another behind a partition wall in the Leeds Civic Theatre as it was being closed down. It carries the writing: Admiralty Patt 7415 Valve NU4 Serial No. 29875G Year 1943.

The EVS data specifies the leads as follows: "The leads are to be made up of six strands of 0.33mm dia. copper or equivalents and are to be 330mm in free length. The filament leads are to come through the pinch at one end, and the anode lead either through the other pinch or through the glass bulb. The leads are to be suitably insulated to within 50mm of the free ends and coloured as above [filament yellow, anode red]. They shall be bound back to the necks of the valve, the leads at each end being equally spaced around the neck. In the re-entrant part of the seal, the leads are to be protected with glass beads, or glass tubing. The insulation on the leads must not be liable to slip; lead stops may be employed. The methods actually used will be checked at Type Approval or as necessary."