The CV187 high voltage half wave rectifier was designed to have an effective series resistance of 600 Ohms and to feed a reservoir capacitor of not more than 4 µF. A pair would be used to provide high voltage full wave rectification. The U19 was the prototype.
In this exhibit the main insulators and spacers are ceramic. In other examples mica discs are used. The original U19 has the cruciform insulators and this was probably made by M-OV.
The top of the envelope matches exactly the top of the GEC U19 seen here.
The wide glass tube envelope is 51 mm in diameter and, excluding the B4 base pins, is 162 mm tall.
Reference: Data-sheet. Type CV187 was first introduced in 1947.
