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 Ω.
The Type designation is also found within an elliptical lozenge typical of M-OV production.
The anode has a central cavity and two side flanges that connect to the supports. The side flanges are positioned at the points of maximum heat production.
The filament is tensioned by coiled springs mounted above the top mica sheets. The ribbon filament with white oxide coating is just visible.
The pinch and lower fixings.
The classic envelope is 51 mm in diameter and, excluding the B4 base pins, is 167 mm tall.
