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Tag: VLF

QSL SAQ Grimeton Xmas 2023 on 17.2 kHz

Of the 4 SAQ Grimeton broadcasts I was able to listen to in 2023 this was by far the best reception with a clear CW signal, S4. A week later I received their e-QSL!

QSL SAQ Grimeton Christmas 2023
e-QSL for the SAQ Grimeton Christmas Eve morning transmission 2023

SAQ Grimeton is a former wireless telegraph station in Sweden. It generates radio signals using an AC generator (called an alternator) designed by the Swedish engineer Alexanderson. This technology was used prior to the development of vacuum tube oscillators. You can learn more about the history of this station and its planned transmissions on the website of the Alexander assocation.

Next SAQ transmission 24th december

QSL SAQ Grimeton Sweden
e QSL from SAQ for UN-day 2023 transmission

On Christmas Eve morning, Sunday December 24th 2023, SAQ Grimeton is scheduled to be on the air, to send out the traditional Christmas message to the whole world, using the 200kW Alexanderson alternator from 1924, on 17.2 kHz CW.

Program and transmission schedule:
08:00 CET (07:00 UTC: The transmitter hall at World Heritage Grimeton is opened for visitors.

Transmission & YouTube Live stream:
08:25 CET (07:25 UTC): Live stream on YouTube begins.
08:30 CET (07:30 UTC): Startup and tuning of the Alexanderson Alternator SAQ.
09:00 CET (08:00 UTC): Transmission of a message from SAQ.

Test transmissions
We are planning to carry our some test transmissions on Friday, December 22nd, approximately between 13:00 CET (12:00 UTC) and 16:00 CET (15:00 UTC). SAQ will be on the air shorter periods of time during this interval, when we will be carrying out some tests and measurements. Your comments are welcome to

More info on

QSL SAQ Grimeton UN-day

I received this e QSL from SAQ Grimeton, Sweden, for the reception of their UN-day transmission. The event took place on October 24th, at 15:00 UTC on the usual 17.2 kHz. I struggled to get a readable signal at my home QTH this time. So I used the Twente SDR as an alternative. Funny thing is that contrary to my expectations their previous transmission around noon mid summer resulted in a much better signal.

QSL SAQ Grimeton Sweden
e QSL from SAQ for UN-day 2023 transmission

QSL DCF77 Time-Signal 77.5 kHz

QSL DCF77 Mainflingen
QSL DCF77 Mainflingen Time-Signal 77.5 kHz

I received this beautiful QSL card DCF77 Time-Signal on 77.5 kHz by mail. The transmitter is located in Mainflingen, Germany. The QSL was accompanied by a folder on how time is managed. I also received a 2009 magazine from the PTB (Physikalisch-Technischen Bundesanstalt) with a special topic on 50 years of DCF77. This magazine is also available online. I sent my report to .

As you can read on the QSL there is no voice announcement of the time. Instead the date and time are transmitted by in code through the interval between second markers (0.1 s = “zero”; 0.2 s = “1”). You can see this in my waterfall map below. The gap prior to second 53 and 57 is twice as big. At the minute there is no gap.

DCF77 signal. The binary code is clearly visible.

QSL SAQ Grimeton Alexanderson Day

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.

QSL SAQ Grimeton 17.2 kHz
e QSL SAQ Grimeton 17.2 kHz Alexanderson Day 2023

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.

QSL Grimeton SAQ 17.2 kHz

The VLF Grimeton transmitter in Sweden was in the air on February 13th celeberating “World Radio Day”. This truly is a heritage station, recognized by UNESCO as such. During the event they ran a YouTube Video to show you what it takes to bring a 100 year old transmitter to life… The transmission was – of course – in Morse Code. This e-QSL card marks the lowest frequency I’ve ever received in my DX-ing career!
Learn more about Grimeton on:

QSL Grimeton SAQ, Sweden, 17.2 kHz

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