Alexanderson Day
June 28, Saturday

Historical Significance
The Alexanderson alternator was developed by Swedish-American engineer Ernst Alexanderson and played a crucial role in early transatlantic wireless communication. Before the advent of modern electronics, this electromechanical device enabled long-distance radio transmissions, particularly for maritime and military communication. Grimeton’s station, built in the 1920s, served as a key link in global communication networks before being rendered obsolete by newer technologies.
Activities and Demonstrations
On Alexanderson Day, visitors can witness a live transmission using the original alternator, which is manually started and operated by trained engineers. The transmission is typically sent in Morse code and received by amateur radio operators around the world. In addition to the transmission, the event includes:
* Guided tours of the Grimeton Radio Station and its preserved machinery
* Lectures and presentations on radio history and technology
* Exhibitions featuring vintage radio equipment and communication artifacts
* Activities for children and families to explore the science of radio
Global Participation
Amateur radio enthusiasts and historians from around the globe tune in to the Alexanderson Day transmission. Many send reception reports to the station, which are often acknowledged with commemorative QSL cards. The event fosters international appreciation for the heritage of radio communication and the technological ingenuity of the early 20th century.
Preservation and Education
Alexanderson Day also serves as a platform to promote the preservation of historical technology and to educate the public about the evolution of communication. The Grimeton Radio Station is maintained by the non-profit organization Alexander – Grimeton Veteranradios Vänner, which works year-round to keep the alternator in working condition and to share its legacy with future generations.