Triode Triode A triode is an electronic amplifying vacuum tube (or "thermionic valve" in British English) consisting of three electrodes inside an evacuated glass envelope: a heated filament or cathode, a grid, and a plate (anode). Developed from Lee De Forest's 1906 Audion, a partial vacuum tube that added a grid electrode to the thermionic diode (Fleming valve), the triode was the first practical electronic amplifier and the ancestor of other types of vacuum tubes such as the tetrode and pentode. Its invention founded the electronics age, making possible amplified radio technology and long-distance telephony. Triodes were widely used in consumer
Valve RF amplifier Single Ended Triode (DH-SET) audio amplifiers use radio transmitting valves originally designed to operate as RF amplifiers in the high frequency range. The most efficient valve-based RF amplifiers operate Class C. If used with no tuned circuit in the output, this would distort the input signal, producing harmonics. However, class C amplifiers normally use a high Q output network which removes the harmonics, leaving an undistorted sine wave identical to the input waveform. Class C is suitable only for amplifying signals with a constant amplitude, such as FM, FSK, and some CW (Morse code) signals. Where the amplitude of the