MS4B MOV CATKIN VALVE, 1933

The Marconi Osram Valve Company Nicknamed this shape as a 'Catkin' A miniature cooled anode tetrode, the idea was to dissipate as much heat as possible from the anode to the air. Inside the can was a metal envelope that was in fact the anode itself, the can was added to prevent the user getting a shock from the anode. This valve is a screened RF Tetrode Frequency Changer.
See Item A0637 for an earlier version.

A0638