Receiving 17kHz Radio Signal from SAQ in Sweden using Modest Equipment

[@yrath5034]

I'm a Brit living in Hungary and I've received it before using the same mini-whip also bought directly from PA0RDT. The noise/QRM is a bit high where I live, so on the centenary transmission we listened on WebSDR. For the 24th of December transmission I'm going to build a wire loop on a bucket (or if I don't get the supplies in time, then a coil around a ferrite rod) and use an up-converter with my IC-705 and go to a very RF quiet area (up a mountain!). My daughter (who is 10) loves it as she has been having weekly morse lesson for the last year and recently passed her amateur radio licence and obtained her morse certificate.

[@fotografm]

Wow - that sounds like a great plan and I am so happy for your daughter being interested in CW and radio ! Let's see how my loop antenna with ferrite rod backup plan works out :-)

[@TomSherwood-z5l]

I saw the video of all the astounding preliminaries to put that thing on the air. Lots more than I ever imagined.

[@fotografm]

Indeed. It reminded me of starting up a steam engine or an old power station !

[@subdynoman]

Is there a link to that video I'd like to see it 👍

[@Mike-H_UK]

Very interesting!

[@fotografm]

Thank you !

[@bill-2018]

Nice try. Hope you get it sorted before Christmas day. I have previously listened on my G4CLF based tcvr but it wasn't too good at such a low frequency. 60 kHz Anthorn was a good signal. I did make a low frequency converter with an xtal and Plessey SL6440 but I've no idea where it got to. G4GHB.

[@karhukivi]

It is possible to receive the VLF transmission with a coil of wire plugged into the sound card of a computer and spectrum analysing software which can be downloaded 9soe for free) from the web. I used a 40 turn coil of about 50cm diameter. The shop at Grimeton sell a small hobby receiver using a 555 chip as a demodulator and a small coil antenna. That works to at least 1500 km from the transmitter.

[@fotografm]

Interesting experiment. I just bought a big plastic box to wind 400 turns of wire around. You need some parallel capacitors to tune it to the right frequency. I will try it first without a preamp and then with a preamp. Let me know how yours goes and I will publish my results when I have some ! Your 40 turns sounds like it might be too few though...

[@karhukivi]

@@fotografm I didn't even tune it so that I could see the spectrum from about 10 kHz up to the limits of the soundcard AtoD converter, about 24 kHz (half the 48 kHz sampling rate) A faster soundcard (e.g. 96 kHz) would cover a wider spectrum.

[@fotografm]

@@karhukivi I see. Yes - without tuning it would be broadband but the signal levels may be low.

[@karhukivi]

@@fotografm There are quite a few radio hams interested in VLF reception and have websites and software, e.g. Spectrum lab with which to view these signals. Also a few videos on YT about it. The signal strength is good due to the high power of the transmitters but SAQ is not run at the full power, nevertheless it ca be detected with simple receiving equipment and as it is in AM, the Morse can be heard. The other Txs went over to MSK modulation some years ago.

[@subdynoman]

Now i wonder what bandwidth the fcc is monitoring 😮 I also wonder how many watts they used to transmitt that 17khz and what that antenna looks like.

[@fotografm]

DC to daylight of course 🙂 Transmitter is 200kW to a wire antenna using hundreds of metres of wire !

[@subdynoman]

@@fotografm WWWWOWWWW!!!

[@KarlWitsman]

Have you tried the beta of SDRConnect from SDRPlay? I believe there is a Mac and Linux version, since you're leaving Windows.

[@fotografm]

Yes I tied that on Ubuntu and it's ok. It is not quite as polished as sdrconsole though but at least it works.

[@subdynoman]

17k isn't that near audible?

[@stargazer7644]

Yes, if your ears could hear radio waves.

[@fotografm]

Indeed it is. Luckily it is an electromagnetic signal not a sound one otherwise it would drive dogs and bats crazy !

[@subdynoman]

@fotografm What is the signal strength and I'm still confused about the antennas used...that's such a low frequency I'm amazed. I've always thought that it needed to be above a certain Ghz, now my mind has to think that even at extremely low frequency there could be transmission. I was just researching the quarter wave length of 60hz and couldn't believe the distance. Things like Schumman resonance are starting to make more sense. Edit, ok, looked into the antenna and I understand now 👍

[@davidholman2536]

Or teenagers crazy. They can hear switched mode power supplies. Physics teachers can exploit this in class, I believe 😅.

[@fotografm]

@@subdynoman Yep. Even such low frequencies can propagate as EM waves. The PA0RDT miniwhip antenna is amazing. It's only 4cm long which is a miniscule fraction of the wavelength but it really works. It is actually an electrostatic probe more than a radio antenna. The Schumann signals around 6Hz can also propagate around the Earth trapped in a waveguide between the ground and the ionosphere. I will take a listen there but you need a really good filter to filter out the huge signal at 50/60Hz from the mains power supply.

[@TomSherwood-z5l]

I suspect that I could receive a signal from every piece of Chinese rubbish electronics, internet line, computer, LED light, power line, and charger within 5 miles on 17.2 KHz at my location. The desired signal maybe 40 dB below the noise level.

[@fotografm]

I know that problem well. Sometimes I turn everything off and just run on battery power. It helps but doesn't suppress noise from my nighbours of course. Also my solar charge controllers are really noisy !