Allgemeinen Elektrizitäts-Gesellschaft, Berlin, around 1912
9 x 31 cm, ca 5 kg
This was the first attempt to make an amplifier tube. It was developed from the quicksilver vapor-filled tube and was based on various forms of a gas discharge that was altered by means of a voltage applied to the sieve-like aluminum plate. This controlled the current between the anode and the cathode. The tube reacted slowly due to the rather lethargic charging of the chamber and it was only once the device later was modified through the use of a grid and high-vacuum tubes that it could be used in practical application.