It was built in 1923 and has the only workable machine transmitter in the world. For its radiating element it uses a wire aerial hung on six 127-metre high freestanding steel towers looking like gigantic pylons. These towers are grounded. On July 2, 2004 the Grimeton VLF transmitter was declared a World Cultural Heritage site by UNESCO. The twin station Nadawcza Radiostacja Transatlantycka Babice in Babice, Poland was destroyed in 1945.
The VLF transmitter Grimeton was used until the fifties for
transatlantic radio telegraphy to Radio
Central in Long Island, New
York, USA. After the fifties it was used until 1996 for
transmitting orders to submarines. In 1968 therefore a second
transmitter was installed. This transmitter uses transistor and
tube technology unlike the machine transmitter, which works on 17.2
kHz, designed for frequencies around 40 kHz, but using the same
aerial. In 1996 the machine transmitter became obsolete and went
out of service. Because it is in good condition it was declared a
national monument. On special occasions such as Alexanderson Day it
is used for transmitting Morse messages on 17.2 kHz. Its signal for
identification is SAQ (... .- --.- )
The machine transmitter can be visited in the summertime. It is a great attraction especially on Alexanderson Day.
The transmitter from the 1960s is still used by the Swedish Navy. Since it uses the same aerial as the machine transmitter a simultaneous operation of both transmitters, which would require expensive frequency filters, is not possible. So these special transmissions are very rare.
The Grimeton VLF transmitter location is not only used for VLF transmission. It is also used for shortwave transmissions and for FM and TV broadcasting. Therefore a 260 metre high guyed steel framework mast was built in 1966 next to the building containing the transmitter for 40 kHz.
Radiostationen Grimeton (SAQ) on Foursquare