| Varberg Radio Station * | |
|---|---|
| Country | Sweden |
| Type | Cultural |
| Criteria | ii, iv |
| Reference | 1134 |
| Region ** | Europe and North America |
| Inscription history | |
| Inscription | 2004 (28th Session) |
| * Name as inscribed on World Heritage List ** Region as classified by UNESCO |
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The Grimeton VLF transmitter is a VLF transmission facility at Grimeton close to Varberg, Sweden. It has the only workable machine transmitter in the world and is classified as World Heritage Site.
The transmitter was built in 1922 to 1924[1]; to operate at 17.2 kHz, although it is designed for frequencies around 40 kHz. The radiating element is a wire aerial hung on six 127-metre high freestanding steel pylons, that are grounded.
The Grimeton VLF transmitter location is also used for shortwave transmissions, FM and TV broadcasting. For this purpose, a 260 metre high guyed steel framework mast was built in 1966 next to the building containing the 40 kHz transmitter.
In 1945 the Grimeton VLF transmitter's twin station Nadawcza Radiostacja Transatlantycka Babice in Babice, Poland was destroyed. Until the 1950s, the Grimeton VLF transmitter was used for transatlantic radio telegraphy to Radio Central in Long Island, New York, USA. From the 1960s until 1996 it transmitted orders to submarines in the Swedish Navy.
In 1968 a second transmitter was installed which uses the same aerial as the machine transmitter but with transistor and tube technology. The machine transmitter become obsolete in 1996 and went out of service. However, because it was still in good condition it was declared a national monument and can be visited during the summer.
On July 2, 2004, the Grimeton VLF transmitter was declared a World Cultural Heritage site by UNESCO. It continues to be used on special occasions such as Alexanderson Day to transmit Morse messages on 17.2 kHz. Its call sign is SAQ. 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. Therefore the special transmissions from that machine transmitter are very rare.
Recent transmissions from SAQ were made on Jul. 4, Oct. 24, and Dec. 24, 2010, and on Jan. 4, April 14 and July 3, 2011. The transmission from SAQ at 08:00 UTC on Christmas Eve (24 December) is repeated annually.
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