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| 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 |
