Ernst Alexanderson
Patents and Inventions
Radio frequency (RF) generator, 1909, (US patent No. 1,008,577).






Ernst Alexanderson (1878 1975); a Swedish-American electrical engineer, a pioneer of radio and television development; received 345 US patents. Best known for his high frequency alternator (radio frequency (RF) generator) which enabled the radio transmission of voice, music and TV pictures (US patent No. 1,008,577).

Title Primary Class Description Inventor Assignee Issue Date Patent No.
High frequency alternator 310/169 A radio frequency (RF) generator. The Alexanderson mechanical alternator: a high-frequency generator, up to 100 kHz, for longwave transmissions, which made modulated sound radio broadcasts practical. It was one of the first devices capable of generating continuous radio waves needed for transmission of amplitude modulation by radio (unlike the spark-gap transmitters and arc converters also used at the time), and was used for a short period through the 1920s in the first AM radio transmitters, until it was replaced by vacuum tube transmitters. Ernst F. W. Alexanderson General Electric Company, New York November 14, 1911 US1,008,577
Selective tuning system 455/291 Tunning and frequency selection by a push-pull vacuum tube configuration (Class A Amplifier). Ernst F. W. Alexanderson General Electric Company, New York February 22, 1916 US1,173,079
Means for controlling alternating currents 323/355 Magnetic amplifier (mag amp). Magnetic amplifiers were important as modulation and control amplifiers in the early development of voice transmission by radio. A magnetic amplifier was used as voice modulator for a 2 kilowatt Alexanderson alternator, and magnetic amplifiers were used in the keying circuits of large high-frequency alternators used for radio communications. Magnetic amplifiers were also used to regulate the speed of Alexanderson alternators to maintain the accuracy of the transmitted radio frequency (see also US patent No. 1,206,643). Ernst F. W. Alexanderson General Electric Company, New York January 20, 1920 US1,328,797
Television Receiver 348/199 Mechanical TV receiver. Scanning disk and high-frequncy neon lamps to improve television transmission. Ernst F. W. Alexanderson General Electric Company, New York November 29, 1932 US1,889,587


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