Brimar Thermionic Products – Official Site

The R-Type valve that we currently produces uses a fairly simple grid which is just wound around a former to look like a spring. All our next valves will need grids/screens that are very different in size and shape. The grid wires are very fine and need to be supported on backbones to keep their shape.

Grids like these are wound in a different way in order to attach the grid wires to the backbones. Our latest project is to design a system to create notches in the backbone at very regular intervals. The grid wire will be laid into the notches and the notch edges will be smoothed over to trap the wire.

You can see in the image left that our cutting pattern is getting very regular now and so it is on to the next stage of laying the wire and and peening  the edges.

Dave Ian and Pete in their element carefully and slowly nurturing the bulb forming machine back to life. This is a small bulb for ECC83 style dual triodes. Though not yet the correct shape, considering this machine hasn’t run for over 40 years, things are looking very good.

A big thank you goes to our Great British Valve Project volunteers Dave & Ian along with Pete our glass worker and all those that cleaned this machine from its original condition of glass, rust and oil. We have had to provide new electrics, update the gas system, reset the burners and make it work with unleaded glass!  We hope to have this brilliant piece of kit up an running fully soon.