The Alexanderson Alternator at World Heritage Grimeton Radio Station in Sweden is the only remaining, and still functional electro-mechanical radio transmitter from the era of the first Trans-Atlantic radio networks. It was installed in 1924, to create a wireless communication link between Sweden and the US. With a power of 200kW, its radio waves, with the call sign SAQ, will travel around the globe.
A metal disc, with a diameter of 1.6m, inside the Alexanderson alternator, is rotating in a strong magnetic field with 2115 rpm. The disc has 488 cut-outs in its periphery, which is creating a magnetic flux with the frequency 17200 Hz (488 x 2115/60) which is the transmission frequency of SAQ.
It is only sending morse code (CW). The magnetic flux is converted into morse code in the magnetic amplifier, a system which uses a relatively small DC current to control a relatively large AC current, firstly to block/reduce the amplification to the antenna, and secondly to alter the antenna resonance frequency, all controlled by the morse key.
The inventor was the Swedish born chief engineer at General Electric, later RCA, Ernst F.W. Alexanderson, 1878 - 1975.
See our website alexander.n.se for more information and for more videos.
Video information:
The first transmission on Alexanderson Day 2021 was initiated at 10.30 CET (08.30 UTC) with the startup and tuning of the Alexanderson alternator. A message was sent out at 11.00 CET (09.00 UTC).
The team from the Alexander association at the 11:00 transmission:
Superindendent & guide: Fredrik Wiklund
Operator: Anders Törblad
Telegraphist: Kai Sundberg
Mobile camera: Thomas Alexandersson
Video technician: Janne Severinsson
Mentor: Jan Steinbach
Assistants: Anders Börjesson and Jan-Åke Gylling