Simplified visualisation of the radio spectrum, with the VLF band on the far left. At such moments lots of radio enthusiasts tune their radios to 17.2 kHz to copy the telegraph message. The power is driven into a large antenna, which looks like a power transmission line of almost 2 km.Īt least two times a year the machine is powered up by volunteers (veterans) of the Alexander Association to broadcast a message to the world, typically in the early Summer at Alexanderson Day, and on Christmas Eve. At this level the transmitter is running very relaxed, since it is originally built to speed up to 40 kHz with a maximum output power of 200 kW. The gear box causes the generator to produce an AC current of 17.2 kHz with an output power of about 80 kW. It is a true machine, with three main parts: a 500 HP electrical motor, a gear box and a generator. The so-called Alexanderson transmitter is everything you don’t expect of a transmitter. From 2004 the radio station is classified as a world heritage site by UNESCO. In 1996 the transmitter was finally shutdown, after more than 70 years of operation. Later the transmitter was used for submarine communications. It operates on a very low frequency: 17.2 kHz (!). Its first transmitter came on air in 1924 for telegraph communications with Radio Central, New York. SAQ is the callsign of the Varberg Radio Station at Grimeton, Sweden. The Alexanderson Alternator, which generates the 17.2 kHz carrier ( credits).
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