The long-wave transmitter in Grimeton is designed by the Swedish engineer Ernst Alexanderson who is relatively unknown in Sweden, but a very valued and respected inventor in the United States. During his lifetime, Alexanderson had 344 patents granted in electrical engineering and electronics.
The station in Grimeton contained two identical but reverse transmitter devices that run alternately, about a month at a time. The new telegraph connection between Sweden and USA proved to be very stable and reliable, and almost all telegram traffic from Sweden to North and South America were transmitted via Grimeton. It took until 1938 before the new technology with valve for shortwave began to be used alongside the machine transmitters. World War II increased the need for foreign telegram connections via radio dramatically, and shortwave transmitter were installed briskly at the station in Grimeton. The old machine transmitters were used at times during the war to transmit diplomatic telegrams to certain European countries but also telegrams to submarines. After World War II the telegram traffic was mainly transmitted using the short wave transmitters. The old long wave transmitter became more rarley used. In 1960, one of the to long wave transmitters was scrapped in order to make more space available for short wave transmitters.
Today, the long wave transmitter in Grimeton is operated for telegram transmitting a few times each year. It results in reports from listeners in many countires. Read more about the listeners in Listening to Grimeton.