Motor-generator - High-frequency Machines

High-frequency Machines

An Alexanderson alternator is a motor-driven, high-frequency alternator which provides radio frequency power. In the early days of radio communication, the high frequency carrier wave had to be produced mechanically using an Alternator with many poles driven at high speeds. The Alexanderson alternator produced upward of 100 kHz with power outputs upward of 200 kW. While electromechanical converters were regularly used for long wave transmissions in the first three decades of the 20th century, electronic techniques were required at higher frequencies. The Alexanderson alternator was largely replaced by the vacuum tube oscillator in the 1920s.