World Heritage Grimeton Radio Station

Grimeton Radio Station in southern Sweden, is an early longwave transatlantic wireless telegraphy station built in 1922-1924, that has been preserved as a historical site. From the 1920s through the 1940s it was used to transmit telegram traffic by Morse code to North America and other countries, and during World War 2 was Sweden’s only telecommunication link with the rest of the world. It is the only remaining example of an early pre-electronic radio transmitter technology called an Alexanderson alternator.

Parking for the Night next to the antennas

We had to stop here and visit Grimeton, because this historic radio station is a unique piece of wireless communication history which shows the effort of mankind to develop the unbelievable – the wireless transmission of information world wide.

It was added to the UNESCO World Heritage List in 2004, with the statement: “Grimeton Radio Station, Varberg is an outstanding monument representing the process of development of communication technology in the period following the First World War.” The radio station is also an anchor site for the European Route of Industrial Heritage.

Private tour in times of Corona
Enthusiastic tour guide who gave us a fantastic insight of the World Heritage
The international radio network in 1924
6 Antenna towers – 127 metres high – are used only to transmit
Entering the transmitter hall built in 1922
Transmitting frequency is very low VLF, 17,2 kilohertz require an antenna length of 2,2 kilometres
Control panel for the transmitter
The heart of the transmitter:  Alexanderson alternator, producing the 17,2 khz frequency

The motor to drive the generator is capable of delivering 500 HP (approximately 370 kW). It is supplied by a 2,200V, and turns at 711.3 rpm to obtain the specified frequency of operation. The complete transmitter set weighs about 50 tons.

The transmitter hall which shows the equipment of 1924 which is still operational

The development of the “vacuum tube” made it possible to generate and control higher radio frequecies. This made the usage of short wave suitable for radio communication from 1930s onwards.

Over the time more than 10 generations of short wave transmitters were used in Grimeton.

All kind of vacuum tubes of the early days of wireless communication

The transmitter of 1924 is still in operational condition, and each year on a day called Alexanderson Day it is started up and transmits brief Morse code test transmissions, which can be received all over the world. See: LISTENING REPORTS

Try to key “SAQ” in morse code, the callsign of Grimeton Radio Station
Radio controls of 1924
sending: … .- –.- “SAQ”
New technology from about 1940 – a “short wave” antenna
The antenna feeding point of the 1924 17,2 Khz transmitter
First message sent to North America
Morse coding our own message
and it arrived at the other end!
The development of mobile communication from 1950 to 2000

Maybe you have to be a radio communication enthusiast to appreciate this relict of technology but we were fascinated. When it was built, it was at the top of technology but soon it was outdated by new developments. A process which seems to continue faster and faster.

GRIMETON official homepage

As the weather didn’t inspire us to stay longer in Sweden, we were now on our way to Denmark, more on our next post!

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