I received an e- QSL from SAQ Grimeton, Sweden, for their transmission on 17.2 kHz to celebrate Alexanderson Day.
Ernst Alexanderson was the inventor of the Alexanderson alternator, a rotating machine used for the generation of a high frequency alternating current, which could be used to produce an electromagnetic wave for radio transmissions. The first alternator based stations were installed in 1906 for long wave telegraphy. In the early 1920s vacuum-tube transmitters came available, replacing the alternators. The Grimeton historical station is the only station in the world that still operates on the basis of an alternator.
I was a bit worried that it would be difficult to receive SAQ on VLF 17.2 kHz at noon in the middle of the summer. Not that I know a lot about VLF propagation. But the signals came through in much better quality than last time I received them on World Radio Day on February 13th this year.