The VU508 is high voltage rectifier designed for high power applications. The U19 (M-OV) and the CV187 are essentially the same valve. When looking at the different interpretations of this specification from different companies the variations in construction are interesting. Here the design uses mica discs to hold the electrodes at the top and the bottom.
The valve also carries the old stores code of 10E/520.
The maximum reservoir capacitor that can be fed is 4 µF and the valve needs a minimum effective series resistance of 600 Ohms.
The anode with flanges in the centre of the working face.
The pinch with the filament connections.
At the top the filament tension springs can be seen. The wire hooks pass into the top of the anode and so the filament tape cannot be seen. It is oxide coated except for the section that passes over the tension hook.
The classic envelope is 51 mm in diameter and, excluding the B4 base pins, is 163 mm tall.
