Grimeton VLF transmitter, Industrial radio station in Varberg, Sweden

The Grimeton VLF transmitter is a radio station in Varberg fitted with six 127-meter towers that support extensive antenna wires for long-distance communication. The facility uses an Alexanderson alternator system with rotating magnets that generate signals at 17.2 kilohertz frequency.

The Riksdag decided in 1921 to build a wireless telegraph link with the United States; construction ran from 1922 to 1924, with the transmitter and antenna designed by Ernst Alexanderson and the station building by Carl Åkerblad. The first direct radio connection between Sweden and the USA opened in December 1924, and King Gustaf V inaugurated the station on 2 July 1925. During World War II it handled traffic with the USA when cable links were cut, and the Swedish Navy later used SAQ to reach submerged submarines.

The call sign SAQ comes from the station's original name, and the transmitter is still run on open days such as Alexanderson Day, held on the last Sunday in June or the first Sunday in July. Visitors can watch the 200 kW Alexanderson alternator start up and send a short Morse message on 17.2 kHz.

The site offers regular guided tours where you can see the working equipment and understand how the system operates in practice. Wear comfortable shoes, as visiting the towers and outdoor areas means walking across the grounds and climbing stairs.

The alternator's 200 kW output at 17.2 kHz gives a wavelength of about 17 km, so the antenna needed six 127-metre towers carrying twelve copper wires 2.2 km long. The towers were aligned to send the signal over the Skagerrak between Skagen and Norway, keeping as much sea and as little land as possible on the path to Long Island.