Grimeton on 17.2kHz

More details here:

73 Chris


Thanks for the heads up, Chris!
It was fun listening to the SAQ transmission and it was so simple! Just fed the signal from my “Mini-Whip” antena into the computer sound card and ran SAQrx. QRV within 15 minutes on LF :slight_smile:
I’m already looking forward to the next transmission on the morning of December 24th.
73, Roman


Unfortunately I wasn’t near a radio at the time, but the live stream of the transmission was recorded:

It worth watching the startup sequence and the keying relays in action :+1:



Thanks @g4ivv for that YouTube link. It is an impressive equipment. I had the chance to visit Grimeton in June this year, therefore it is even more interesting to see the transmitter being operated.
If you are in Sweden, visit Grimeton. It‘s worth

73, Klaus


Fantastic video, thank you Jonathon,
73, Paul

Grimeton SAQ was at least audible with an under-roof antenna in downtown Hanover with S9+ noise.

73 Chris


Hi Chris,
That’s a very interesting transmitter. I enjoyed watching the video; I loved that old fashioned machinery.

This makes me think how lucky we are nowadays, carrying all those tiny low powered rigs and yet be able to work long distances with a silly wire antenna and get such high quality audio.

I can’t imagine carrying all these water pumps, engines and switches to a summit to transmit, nor spendind all that time required to get the pressure and voltage to start transmitting, I would never meet the scheduled alert time, hi!

Thanks for sharing
73 Ignacio


The ingenious technique of long waves from the 1920s is still fascinating today. It’s hard to believe that the possibilities of shortwave escaped the attention of professional technicians during this period. Marconi himself was annoyed about this.

The Grimeton emmision motivated me to resume my attempts at 630m.

In the following clip you can hear DJ6CB at a 500W station from a distance of 140km.

My portable 80m <=> 630m transverter has 20W and an internal antenna tuner for wires of 20-40m length. My rapport was 339.

Unfortunately, there are hardly any remote stations here in northern Germany.

73 Chris


Hi Chris, great video of Grimeton; and link to Grimeton. Alway interesting to see the tuning of historical equipment; and of this transmitter…fantastic to watch. Went to their web site to explore even further, thanks

Geoff vk3sq

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really interesting the vlf world!
thanks Guys for sharing these video. unfortunately I wasn’t in radio.

@DL1CR Chris can you give me some info about your 630mt transverter?
in a future we could made a s2s…

Roberto iw2obx

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Unfortunately I don’t have a comprehensive description of the transverter, only the circuit diagram. But there are many hints here

73 Chris


Hi Chris,

My apologies if this is old hat.

Marconi’s experiments showed stronger signals as the wavelength increased. The ionosphere was not known about. Of course as the wavelengths got longer the antenna efficiency dropped and very high power was used. Unbeknown to everyone the vlf signals propagated in a waveguide formed by the ionosphere and the Earth’s surface.

When amateurs started having success at wavelengths is 100 and 200 m Marconi was alerted. His experiments took him all the way up to 500 MHz with his ship Electra as a mobile Rx station. And as they say the rest is history.



The medium wave won’t let me go.

I don’t have a useful antenna for the 630m band at home. Only 50m of wire laid out in the attic of an apartment building.
But hell, Map | WSPRnet makes the impossible possible. Here the simple equipment, making my 1200km ODX on 475.6kHz.

73 Chris


great, give me some months and we will try a s2s…



I saw a few posts about SAQ on some internet lists and I found myself being drawn into the world of VLF!

I have set myself a challenge to receive SAQ. I’m not so interested in SDR, so I’m going to trya hardware solution.

I’ve seen that the Christmas activities have already been planned and a schedule has been released -

Less than 3 weeks to get ready!

I started designing a home brew superhet but then I found a schematic for a simple up-converter. I figured that my FT-817 could do a better job of receiving than a home brew receiver, and I haven’t got a lot of time to build something!

I’m going to house my up-converter in an Altoids tin for shielding, so I’ve used a prototype board from QRPme, which W1REX gave me years ago. The up-converter adds exactly 10MHz.

I’m still waiting for some parts to arrive but initial tests have provided pleasing results. I’m hearing quite a lot of strong signals in the VLF range, including the time signals from Frankfurt and Anthorn. I’m also hearing some of the submarine coms stations. RTE1 is extremely strong on 252kHz and BBC R4 is S9 on the FT-817, all of this just with a piece of wire in the shack!

(Before frequency calibration)

I’m currently building a ferrite rod antenna and I also plan to build a PA0RDT mini whip. I’ll add a bias tee into my up-converter so I can power the mini whip and ferrite rod pre-amp via the coax.



Excellent results, Colin!
Can you share the schematic, please? (even though it’s obvious :upside_down_face:)
I started a similar project with an old SO42P which I found in my drawer. A few parts still need to be ordered - I hope I can make it until Dec. 24th …

Good luck with the reception of SAQ!

73, Roman


Hi Roman,

I can’t claim any great technical knowledge, but I can build stuff from schematics. I was looking at trying to impedance match the input to an SA612 mixer chip (I’m sitting on the world’s remaining stock I think!!) when I stumbled upon the WB9KZY design. I thought it was worth a shot as I had most of the parts in stock. I’m going to include a bias tee also, so it’s those parts that I’m waiting for.

The design is merely an SA612 mixer with a LF low pass filter on the front end.

I’ve never done any VLF work before so I’m just taking small steps in experimentation. I haven’t measured my low pass filter yet, but I have to get my oscilloscope out to align a ‘customer’ MTR-5B, so I think I’ll sweep the RX converter whilst I have my gear set up. Will be interesting to look at the filter cut off frequency. I heard Spanish signals on 540kHz but the radio goes quiet above that frequency.

73, Colin


Should be around 500kHz. Filter design is very easy to do online.

73 Chris

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The use of FT37-43 cores isn’t the best choice for this application and also the low pass filter is designed for 50 ohm impedance input and output. It’s hard to find out what the input impedance of an SA612 is, but supposedly definitely above 1k and more likely a few k.

I added an extra couple of poles to my filter, so like I said, it will be interesting to sweep the filter!

I salvaged a ferrite rod antenna and mounted it on a scrap piece of wood yesterday. The antenna seems to work OK and is directional, so that’s my plan B antenna.

73, Colin


I’ve completed my VLF up-converter and also my PA0RDT Mini Whip project. I’m now receiving the DCF time signal at S9+. Next on my build list is an audio splitter and level control so I can record audio from my FT817.

SAQ is scheduled to begin test transmissions on 23rd December, so I hope to fine tune my system then.