Philips Historische Producten museum Eindhoven (49/52)

The first triode tube produced by Philips for radio applications (signal amplification), among other radio tubes. This device is possibly a prototype of their PH-IDZ tube (which can be seen at the bottom), whose production began in 1918. It is based on Lee de Forest's Audion tube design, which was initially filled with a gas at a very low pressure (the name is a contraction of audio and ion). Investigations on such tubes, and particularly on their light emission, laid the foundation of the company's gas discharge lamp business.