A magical morning with SAQ Grimeton Radio

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I've been a radio enthusiast since the early 1980s, but it wasn't until recently that I finally got myself a receiver and antenna suitable for listening to VLF (3-30 kHz) (see my earlier blog posting here).

One of my goals with the new VLF setup was to receive one of the special CW transmissions on 17.2 kHz from historical radio station SAQ Grimeton in Sweden.

Grimeton Radio was built during the years 1922-1924 to provide a "longwave" wireless telegraphy transmitting and receiving station for transatlantic telegram traffic with the United States. The first transmitter used was a VLF machine transmitter invented and designed by Swedish engineer Ernst Alexanderson. Grimeton Radio went on the air in December 1924 with the callsign SAQ. Initially transmissions were done on the frequency of 16.1 kHz but this was soon changed to 17.2 kHz.

The Alexanderson alternator transmitter at Grimeton Radio (source)

After some years, new technology had made the Alexanderson machine transmitter obsolete for its original purpose; by the 1930s transatlantic communication had gradually started to switch to shortwave, and vacuum tube shortwave transmitters were used instead.  The Alexanderson transmitter was still used however to communicate on VLF with submerged submarines, and wasn't  decommissioned until the 1990s. Luckily the complete site of Grimeton Radio, including the original VLF machine transmitter, has been preserved as a historical monument. In 2004 the radio station was added to UNESCO's List of World Heritage Sites.

Like mentioned earlier, the original VLF machine transmitter at Grimeton Radio was designed by Swedish engineer Ernst Alexanderson. It consisted of an alternating-current generator (the so called Alexanderson alternator) driven by an electrical motor through a speed-increasing gearbox. When driven at high speed at the correct RPM, the alternator generates a signal on 17.2 kHz. Yes, this means that RF is generated without any electronic parts (like tubes or transistors) involved at all!
Although not in regular use anymore, two or three times a year on special days a CW message is transmitted by Grimeton Radio using this very same historical Alexanderson alternator transmitter!

Traditionally, one of the special transmissions is done in the morning of Christmas Eve, and so was the case this year. And I was extremely happy to manage to catch it! For the first time I was listening to this special station, to a Morse Code transmission generated by a historical, pre-electronic transmitter, the only one of its kind remaining! And on one of the most beautiful and magical days of the year! Goose bumps!

Grimeton Radion at  - 6ºC on the morning of Christmas Eve 2018 (source)

The signals were picked up at PA7MDJ with an SDRPlay RSP1A receiver and a MegActiv MA305FT E-field probe antenna. Below on my SoundCloud account you can listen to the recording I made this beautiful Christmas Eve morning, December 24th, 2018.

The transcript of the received Morse Code message reads as follows:

CQ CQ CQ DE SAQ SAQ SAQ =
THIS IS GRIMETON RADIO / SAQ
IN A TRANSMISSION USING THE ALEXANDERSON 200 KW ALTERNATOR
ON 17.2 KHZ =
WE WISH YOU ALL A MERRY CHRISTMAS AND A HAPPY NEW YEAR =
SIGNED: THE WORLD HERITAGE AT GRIMETON
AND THE ALEXANDER-GRIMETON VETERANRADIOS VAENNER ASSOCIATION AR =
FOR QSL INFO PLEASE READ OUR WEBSITE:
WWW.ALEXANDER.N.SE II WWW.ALEXANDER.N.SE =
DE SAQ SAQ SAQ SK

The message was preceded by a "VVV VVV VVV DE SAQ SAQ SAQ" loop.

In 2003 I visited the Grimeton Radio site to look for a geocache (one of my other hobbies), unfortunately without the possibility to take a look inside the transmitter building, but that's another story.







See also:

https://www.youtube.com/watch?time_continue=2719&v=shqi43EV07c  - Video made at Grimeton Radio during the special Christmas Eve 2018 transmission
https://alexander.n.se/?lang=en
https://en.wikipedia.org/wiki/Grimeton_Radio_Station
http://whc.unesco.org/en/list/1134

How low can you go? Explorations of the MF, LF, and VLF bands.

Last edited: 01.12.2018

I've always been fascinated by ELF, VLF and the lower part of LF, and both the man-made signals and Natural Radio emissions occurring on these bands have always intrigued me. I never had a suitable receiver and antenna for this part of the RF spectrum though.

This changed when some time ago I bought an RSP1A SDR-receiver, and more recently a MegActiv MA305FT E-field probe. This receiver / antenna combination for the first time enabled me to seriously explore the mysterious realm below 100 kHz, all the way down to about 9 kHz (the lower limit of the frequency range of the MA305FT)!

It's really fascinating listening for the first time to the various Time Signal Stations and to the transmissions of the numerous naval stations using these low frequencies to communicate with submerged submarines. On VLF, radio signals are able to penetrate seawater to a depth of up to about 40 metres, depending on the salinity of the water (contrary to higher frequencies which do not penetrate seawater to any significant depth). On ELF the signals can penetrate even deeper, and the Russians are operating a transmitter known as Zevs near Murmansk to communicate with their submarines on a frequency of 82 Hz (yes, Hz, not kHz!). A similar system is (or was?) also in use by the United States on 76 Hz.

The Norviken VLF transmitter (callsign JXN) in Norway can be heard on 16.4 kHz. The station is used to transmit messages to submerged submarines. VLF antennas are huge; the antenna of JXN is made up of three wires spun between two mountains and spanning a distance of over 2 km! (source)

The MegActiv MA305FT E-field probe is manufactured by NTi in southern Germany close to the Swiss border. It's an active antenna of the popular so-called Mini Whip type. Probably the most well known mini whip is the original Mini Whip designed by PA0RDT, and most other mini whip designs are more or less based on the same principal.
Some time ago I already bought a mini whip kit from Van Dijken Electronica, but I never got round to building it. Then, while visiting the yearly VERON Ham Radio Convention in Zwolle early November, I noticed the stand of Bonito with various active E-field (mini whip) and H-field (loop) type antennas for sale. Bonito is closely involved in the designing and testing of the various antennas made by NTi. The MegActiv MA305FT caught my eye, was looking very well built, and was offered for 20 euros below the normal price. I checked the internet and found that the antenna in various reviews was scoring very well. I decided to buy one.

I bought the MA305FT mainly for exploring the VLF, LF, and MF bands, and this is where the antenna really shines, as you'll see later on.

At the University of Twente they have a mini whip antenna in use for their WebSDR. Their mini whip is performing extremely well, and their WSPR reception has become the high standard reference for me for doing rx antenna evaluation. WSPR reception results can easily be compared by checking the spots of the University of Twente (callsign PI4THT) on WSPRnet.org. When doing WSPR reception comparisons, on all bands from LF through to HF 20m (I never checked the higher bands) the mini whip of PI4THT always outperforms my HyEndFed 10/20/40 sloper wire antenna.

When I got home from Zwolle I immediately set up the MegActiv in the back of my small yard at a height of about 3 metres on a PVC pipe placed on a large tripod. The active antenna is powered over the coax feeding cable with the special coaxial power inserter that comes with the antenna. The inserter can be powered in several ways, including from for instance a laptop USB port. The antenna / inserter can be fed with a power source ranging from 5 to 15 Volts DC. I tried powering it with several of the 5 V power banks that I have, but all shut down after a while due to the power inserter drawing very little current and the powerbank thinking nothing is plugged in ( I recently saw a little device for sale at SOTABEAMS which in such a situation will prevent a powerbank from shutting down, and of course such a "keep alive load" could also be homebrewed very easily).

The MegActiv MA305FT active E-field probe. Frequency range 9 kHz - 300 MHz.

Once everything was set up, one of the first things I did was monitoring the 630m MF WSPR frequency (474.2 kHz dial). This looked very promising; the SNRs of the signals received often were not far below of the spots made by PI4THT, sometimes even better! The next day on November 5th I managed to receive the 5 Watt WSPR signal of AA1A in Massachusetts, USA! With this I really outperformed PI4THT, as no MF WSPR spots for US stations were made at all that day at the University of Twente!

Reception of the 630m WSPR signal of AA1A with the RSP1A and the MegActiv antenna

On VLF and the lower part of LF a lot of signals were received with excellent strength, mostly time signal stations and the naval stations mentioned earlier, but also various telecontrol signals and for example the RTTY weather reports from the Deutsche Wetterdienst DDH47 on 147.30 kHz.
In the 1990s I used to be an avid LF NDB DXer, and I really enjoyed rediscovering this part of the radio hobby wth the RSP1A and the  MegActiv. New to me in the field of NDB DXing are the DGPS stations, many of them actually being the old closed down maritime NDBs. I also had excellent reception of various coastal stations with NAVTEX weather and navigational warnings on 518 kHz, and I see some real DX potential here for the dark winter months. With MultiPSK I was able to decode the DDH47, EFR telecontrol, DGPS, and NAVTEX signals.

I'm looking forward to the next Morse transmission of the historical station SAQ Grimeton in Sweden on 17.2 kHz which I hopefully will be able to pick up with the setup described in this blog. The last time I tried it with a wire antenna and I failed. SAQ Grimeton was one of the reasons why I really wanted to improve VLF reception.

Reception with the MegActiv MA305FT on HF so far has been a little disappointing. I expected the reception on HF with the MA305FT at least to be on par with my HyEndFed, but on 40 and 20m WSPR and FT8 the HyEndFed was the clear winner. Compared to 40 and 20m WSPR reception of PI4THT the MegActiv just could not compete at all.
This doesn't mean the MA305FT can't do better on HF though. It could all be a matter of finding the best location and setup for the antenna. To work properly a mini whip type antenna should have the coax shield close to the antenna connected to an earth electrode. I don't have such an earth electrode available yet. At PI4THT they don't have an earth electrode, but the roof on which their mini whip is located contains a lot of metal which serves as the antenna's earth. I might install an earth electrode later on, and more experiments are needed to say something meaningful about the performance of the MegActiv on HF.

The MA305FT opened up. With a jumper an FM broadcast band notch filter can be switched in.

I've heard some people say that an SDR and an active antenna don't match very well, due to the antenna causing overloading very easily. Also I've heard people say that an active antenne like the mini whip is very prone to picking up the omnipresent electrical noise of an urban surrounding. I didn't notice any of this being much worse than with the other antennas I have in use though.

With the recent exploration of the RF spectrum basement, a new radio hobby door has opened up, and I got inspired to continue with more VLF, LF, and MF experiments. I would like to experiment with using special software and a PC soundcard as VLF receiver  (a soundcard with a sample rate of 48 kHz can receive radio signals up to 24 kHz*). One day I'll also built the mini whip kit and see how it compares to the MegActiv.
And who knows, maybe the future sees me transmitting WSPR on 630m MF myself, using the MF Solutions transmit converter described here and here (in combination with my QRP Labs U3S), and an earth-electrode antenna as in use by G3XBM and as described here.

And still the RF spectrum below 9 kHz and Natural Radio remains unexplored. Someday I will also buy or built myself a natural radio receiver.

* I was mistaken earlier and wrote 96 kHz, it should be of course 24 kHz.


See also:

https://en.wikipedia.org/wiki/Very_low_frequency
https://en.wikipedia.org/wiki/Extremely_low_frequency
http://www.vlf.it/zevs/zevs.htm
https://en.wikipedia.org/wiki/Noviken_VLF_Transmitter 
https://www.fenu-radio.ch/en-index1.htm#MegActiv
https://www.vandijkenelektronica.eu/nl/57-antenne-s-en-antennebenodigdheden
http://websdr.ewi.utwente.nl:8901/
https://www.mwlist.org/vlf.php
https://www.efr.de/
https://en.wikipedia.org/wiki/Non-directional_beacon
https://en.wikipedia.org/wiki/Differential_GPS
https://en.wikipedia.org/wiki/Navtex
https://alexander.n.se/the-radio-station-saq-grimeton/saq-transmissions/?lang=en
http://www.472khz.org/
http://www.pa3fwm.nl/technotes/tn09d.html
http://www.pa3fwm.nl/technotes/tn07.html
http://dl1dbc.net/SAQ/Mwhip/pa0rdt-Mini-Whip.pdf
http://dl1dbc.net/SAQ/Mwhip/Article_pa0rdt-Mini-Whip_English.pdf

North to Alaska! (WSPR chatter 3)

Last edited: 30.04.2018

What a pleasant surprise this morning to see that my 200 mW WSPR signals on 20m had been spotted by KL7L in Alaska!

I used my QRP Labs U3S transmitter and a sloping dipole cut for resonance on 20m.

This is WSPR DXCC entity 68 for me.

KL7L hearing PA7MDJ

KL7L is operated by Laurence Howell from his receive facility at Hart Lake Fishook (grid BP51ip) near Wasilla. about 50 miles north of Anchorage. Laurence seems to be very active with VLF, LF and MF receiving experiments, for which the Hart Lake QTH seems to be the ideal location.

In this article Laurence reports on his reception in Alaska of the VLF signals from the SAQ Grimeton transmitter in Sweden. You'll also find some photos there of the KL7L shack, the VLF antennas used, and the view from Hart Lake looking North over the Pole towards Europe (imagine, that's where my tiny WSPR signal came from!)

View from the KL7L Hart Lake receive facility looking North over the Pole towards Europe (imagine, that's where my tiny WSPR signal came from before being picked up by the antenna of KL7L!) (source)

Here you'll find a YouTube movie where Laurence shows a huge homebrew VLF receiving loop. More interesting YouTube videos from KL7L (user "hellozerohellozero") can be found here.

WSPR monitoring and the SDRPlay RSP1A 1 kHz - 2 GHz SDR-receiver

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The SDRPlay RSP1A "DC to Daylight" SDR receiver

The downside of the popularity of stand alone WSPR transmitters like for instance the QRP Labs U3S and the Sotabeams WSPRlite is that more and more hams in the field of WSPR have become transmit-only stations and do little WSPR monitoring or none at all. On the other hand though, if it wasn't for these neat little stand alone WSPR transmitters many radio amateurs would probably never have been active in WSPR at all. I'm one of them; it was my beloved U3S that has made a keen and active WSPR operator out of me.

But we all depend on eachother; without WSPR monitoring stations there's no use in transmitting WSPR beacons, and without transmitting stations there's no use in monitoring. It occurred to me that if you're an active user of a U3S or a WSPRlite, and you're enjoying seeing your WSPR beacons being spotted all over the world, you more or less have the obligation to do the occasional monitoring session, as a favour in return and to keep the WSPR network alive and interesting! To me, being a transmitting-only station has always felt a little selfish.

I've done the occasional monitoring sessions, but only if some special WSPR project was in progress; maritime mobile, floaters, high altitude balloons, expeditions, etc. Still a little selfish and I decided I wanted to become more active with general WSPR monitoring as well. I don't like having my transceiver powered up for longer, extended periods of time though (it occurred to me that manufacturers should build in to their transceivers an on/off switch or a sleep mode for the display to be turned off during extended monitoring sessions).
So, for this reason (and a million others) I decided to purchase the new SDRPlay RSP1A SDR receiver. The RSP1A is manufactured in the UK and receives from 1 kHz to 2 GHz, or to use a popular term, it's a "DC to Daylight" receiver. It's my first experience with a Software Defined Radio, and I must say that I'm really thrilled with all the possibilities the RSP1A brings. It's really nice to also be able to explore the VLF frequency range for instance; for the first time in my life I managed to hear the signals of time signal station DCF77 on 77.5 kHz. I'm planning on making a PA0RDT mini whip antenna to do some more serious monitoring on VLF, LF and MF, including 2200m and 630m WSPR.

My first WSPR monitoring session with the RSP1A was done on 40m and instantly the SDR receiver connected to my HyEndFed 10/20/40m wire antenna managed to pull in the 5 Watt WSPR signals of the DP0GVN beacon on Antarctica for me (earlier, reciprocally the DP0GVN receiving station already picked up my 200mW WSPR signals on 20m, see the addendum to my blog entry of January 13th). I'm really pleased with the reception of the RSP1A.

A nice interview with Jon Hudson from SDRPlay about the new RSP1A can be found here on YouTube.

I also don't like leaving my laptop powered up for extended periods of time, so in the future I might look into the possibility to do WSPR monitoring sessions with the RSP1A connected to a Raspberry Pi.