History of electronic engineering on to develop the first practical and widely used radio wave based communication system. In 1904, John Ambrose Fleming, the first professor of electrical Engineering at University College London, invented the first radio tube, the diode. Then, in 1906, Robert von Lieben and Lee De Forest independently developed the amplifier tube, called the triode. Electronics is often considered to have begun with the invention of the triode. Within 10 years, the device was used in radio transmitters and receivers as well as systems for long distance telephone calls. The invention of the triode amplifier, generator, and detector made audio communication
Valve transmitters circuit. This circuit design has been used at 1296 MHz using disk seal triode valves such as the 2C39A. The grid is kept at ground, the drive is applied to the cathode through a capacitor. The heater supply must be isolated with great care from the cathode as unlike the other designs the cathode is not connected to RF ground. The cathode may be at the same DC potential as the grid if a valve such as the 811A (zero bias triode) is used, otherwise the cathode must be positive with respect to the grid to provide proper bias. This