AC Generators

Just after the turn of the century, Alexanderson began to design alternators (AC generators) based on an idea of Reginald A. Fessenden who used one for broadcasting experiments on Christmas Eve 1906 when voice, singing and music bewildered the radio officers of ships along the US east coast.

The 200 kW alternators for VLF were ready by 1918. Including the very impressive and efficient multiple tuned antenna, they were manufactured by General Electric (GE) and sold by the Radio Corporation of America (RCA) around the world.

In the 1920’s it was the era of industrial race, a desire for peace between countries as well as emigration that became the driving force in the development of engineering. Communication between Sweden and America was done by cable or was transmitted from the radio station in Karls-borg (callsign SAJ) via Great Britain. This was a disadvantage since direct radio communication with America was desired.

After a Parliament decision, the Royal Telegraph Board (Swedish Telecom) settled for the Alexanderson equipment that was also part of a gigantic plan for wireless communications where “Radio Central” on Long Island outside New York was the hub of a global network of longwave sta-tions. In the end, the network had 18 transmitters in continental USA, Hawaii, Wales, Poland and Sweden.

The Swedish transmitting station (SAQ) was built at Grimeton near Varberg on the west coast of Sweden where the countryside would give the radio waves free passage to the sea and onwards across the Atlantic. Two alternators with an output power of 200 kW could be used one at a time or in parallel. The towers carried twelve 2,200 m long wires that connected the six vertical antenna elements from the top of each tower.

In October 1924, the first message from SAQ, i.e. Varberg Radio at Grimeton radio on the Swedish west coast, was sent to the “Radio Central” of RCA at Rocky Point, Long Island, USA. The wavelength was about 18,000 m, soon changed to a frequency of 17.2 kHz.

The commercial service “via RCA” started December 1st 1924. On July 2nd 1925, the station was inaugurated by King Gustaf V sending a telegram to Calvin Coolidge, President of the United States, praising the new link to America. He also praised “the democratic shelter under which millions of Swedes had found new homes.”

The receiving station (SAK) with its 13 km long antenna was built at Kungsbacka further north in Halland county. Like SAQ it was connected to the telegraph station in Gothenburg where the outgoing telegram messages were changed into morse signals and the received signals were changed into telegrams for delivery.

We will now put the history of SAQ on standby giving submarine communication a break-in. The important communication means for subs are longwave to submerged subs and shortwave from subs on or just beneath the water surface.