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Ernst Alexanderson

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description Ernst Alexanderson Overview

Ernst Alexanderson was a Swedish-American electrical engineer who worked for General Electric and RCA. He is best known for inventing the high-frequency Alexanderson alternator, a key technology that enabled early transoceanic radio transmission before the widespread adoption of vacuum tubes. In 1927, he also made early advancements in television technology by demonstrating a mechanical television system. His alternator design remains operational at the Grimeton radio station in Sweden, a UNESCO World Heritage site.

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What did Ernst Alexanderson actually invent?

He developed the high-frequency Alexanderson alternator, a rotating machine that generated continuous-wave radio-frequency power before vacuum-tube transmitters took over. It was built while he was a General Electric engineer and became important for long-distance radio. [National Inventors Hall of Fame](https://www.invent.org/inductees/ernst-f-alexanderson)

What happened with the Alexanderson alternator on Christmas Eve 1906?

A two-kilowatt, 100,000-cycle machine was installed at Reginald Fessenden's Brant Rock station in Massachusetts. On December 24, 1906, the station carried a broadcast that included speech and a violin solo. [National Inventors Hall of Fame](https://www.invent.org/inductees/ernst-f-alexanderson)

Was Alexanderson connected to RCA as well as General Electric?

Yes. He spent most of a 46-year career at General Electric and also worked with RCA during the development of radio and television systems. The National Inventors Hall of Fame credits him with 322 patents. [National Inventors Hall of Fame](https://www.invent.org/inductees/ernst-f-alexanderson)

Where can I see a working Alexanderson transmitter today?

The surviving operating example is at the UNESCO-listed Grimeton Radio Station in Varberg, Sweden. The station preserves a 200-kilowatt Alexanderson transmitter and six 127-metre antenna towers from the early transatlantic radio era. [UNESCO](https://whc.unesco.org/en/list/1134/), [Grimeton](https://grimeton.org/en/2023/10/18/grimeton-world-heritage-site-broadcasts-un-day-message-on-october-24-2023/)

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