Solenoid_prototype

This tube was originally designed by Henry Huppert when working for Moorhead, The particular design of the glass bulb was utilised in the upper narrow part to test a concept for supporting the solenoid spool by using the glass envelope. Later prototypes have been found which have a metal strut to support the spool. The solenoid replaced the grid in these tubes and one wire from the solenoid is connected to the grid pin. The other end wire is connected to the brass base shell. This system was adopted throughout the short commercial life of the tube.