VALVE TYPES & MANUFACTURING TECHNIQUES (xiii) - B7G & B9A VALVE ASSEMBLY GOES ON AND ON - VALVE BASE PREPARATION

With the electrode cage sorted, the next stage was to prepare the valve base.  In the valve build described - the DF91 - this has a B7G glass base, the manufacture of which was the subject of an earlier blog entry where we left the valve base as a glass button having seven composite wires, each comprising of a valve pin, a seal and an electrode support wire, all very nice, but an electrode cage cannot be mounted on the valve base as it stands.

The valve base prep team had to first prepare the base using a special machine that both cuts the electrode support wires to correct length and then bends them to the exact position to enable mating with the corresponding connection from the electrode cage.

In the photo below, on the left, you can see a valve base as supplied and then to the right after electrode trimming and bending prior to mounting the electrode cage onto the base: -