Simple VLF Receiver

SM6LKM's excellent PC based VLF receiver

In testing my Chirpy 10m transceiver, I used the simple PC based VLF receiver by SM6LKM as a bolt-on SDR. This little VLF receiver works very well as a stand-alone VLF receiver that tunes the 0-22kHz frequency range. Simply by sliding the cursor to any frequency it produces an audible signal just as you would get by tuning a conventional receiver.  Bandwidths are adjustable down to around 300Hz. For my video showing this in action listening to VLF signals (via my loop and small preamp) see http://www.youtube.com/watch?v=TDxRhQYg7lQ. With the SM6LKM VLF receiver you can clearly hear the Omega beacons around 11-14kHz, SAQ when transmitting on 17.2kHz, and various MSK military signals around 18-22kHz. It has also proved useful when carrying out earth-mode (through the ground) VLF communication tests.

SAQ 17.2kHz this week

There will be an extra transmission with the Alexanderson alternator station SAQ on 17.2 kHz on Thursday April 14th 2011 at 12:45 UTC with tuning up some time before.   The transmission is directed to "The 5th European Conference on Antennas and Propagation" in Rome, Italy. There will be no QSL verification of this transmission.

SAQ Jan 3rd

SAQ was audible well last night around 2330z tuning up for a transmission on 17.2kHz CW at midnight. The signal was about 20dB above noise using the 20m spaced earth electrodes as an antenna.

Night time SAQ VLF transmission - Jan 4th 2011

There will be an extra transmission with the Alexanderson alternator on 17.2 kHz primarily for listeners in North America, the times shown below. QSL cards will be issued for correct reports. These can be sent via post, email or via the SM QSL bureau.

16:00 PST (Pacific Standard Time) in USA. Monday, Jan 3rd, 2011 

19:00 EST (Eastern Standard Time) in USA. Monday, Jan 3rd, 2011

00:00 UTC (Coordinated Universal Time) Western Europe. Tuesday, Jan 4th, 2011

01:00 CET (Central European Time) and local time in Sweden. Tuesday, Jan 4th, 2011

SAQ transmission on Dec 24th (17.2kHz)

The historic VLF alternator transmitter SAQ in Grimeton, Sweden will be transmitting next on Dec 24th at 0800z on 17.2kHz with tune-up some 30 minutes before. QSL cards will be issued for reports of successful reception if sent by email  to info@alexander.n.se or the SM QSL bureau (I think). This is a good chance to try out your VLF receivers. The antennas at Grimeton are a bit bigger than mine on VLF!

Additional SAQ VLF transmission

From SM6NM/Lars

There will be a transmission with the Alexanderson alternator on 17,2 kHz on United Nations Day Oct 24 2010 at 11:00 UTC. Start up and tuning from about 10:30 UTC. This time we do not require any QSL-reports and will not verify. We intend to continue with our annual transmission on Christmas Eve (morning), Dec 24, at 08:00 UTC with tuning up from 07:30 UTC. D.S.

 

SAQ (17.2kHz) CW VLF transmission Sunday July 4th

There will be a further transmission from the historic VLF transmitter at Grimeton, Sweden on July 4th at 0900 and 1200 UTC on 17.2kHz CW with tune-up 30 minutes before each transmission. E-mail to: info@alexander.n.se or fax to: +46-340-674195 or via: SM bureau or direct by mail to:

Alexander

Grimeton Veteranradios Vaenner, 

Radiostationen                          

Grimeton 72

SE-430 16 ROLFSTORP, SWEDEN

See: www.alexander.n.se

Improved VLF converter

Chris HB9DAO has sent me a copy of his modifications to my SAQ VLF converter that was published a few years ago in SPRAT. His changes make the converter a bit more "bullet proof" in the European environment where there are lots of very strong signals in the VLF-MF frequency range. The schematic is attached.

OK1VEN builds my SAQ converter - see his video

OK1VEN has been building a version of my SAQ converter which up-converts the 17.2kHz signal to HF. He produced a time-lapse video showing him building it, which he put onto YouTube recently. His version looks a lot neater than the G3XBM original!

See http://www.youtube.com/watch?v=x-Azk9wmIvg

SAQ (17.2kHz VLF) reception

This link takes you to a recording of SAQ on 17.2kHz as heard by M0LMH in IO93 square.  It is quite strong when the signal starts. I listened on the Dutch online SDR and SAQ was not as strong there as I would have expected at 1600z. This is a recording of SAQ in Connecticut USA made by Jay W1VD earlier today.

SAQ (17.2kHz) - on line receiver

Dec 10th the transmitter at SAQ (Sweden) on 17.2kHz is transmitting a special CW message. Also there is a transmission on Dec 24th. An on-line SDR in The Netherlands that can be used to listen to this. See  http://websdr.pa3weg.nl/ .  Alternatively, try listening with a simple up-converter or simple VLF receiver. 

Extra transmission on 10th December
In order to celebrate the 100th anniversary of the Nobel Prize to Guglielmo Marconi and Karl Ferdinand Braun, we plan to be on air on 10th December at 08.00 UTC and 16.00 UTC. No reports are required and no QSL-cards will be given.

Traditional transmission on Christmas Eve 24th December
SAQ will be on air on 24th December at 08.00 UTC. The frequency is as usual 17.2 kHz CW. Reports are welcome and will be confirmed by QSL-cards.

SAQ (17.2kHz): extra transmission Dec 10th 2009

There will be a CW transmission with the Alexanderson alternator at SAQ on 17.2 kHz on Dec 10th 2009 at 08:00 UTC and again at 16:00 UTC the same day.

The reason for the extra transmission is a centenary commemoration of the Nobel Prize given to Guglielmo Marconi and Karl Ferdinand Brown. SAQ does not want QSL-reports this time and will not verify. They still intend to continue with their annual transmissions on Christmas Eve (morning), Dec 24, at 08:00 UTC with tuning up from 07:30 UTC.

This is always a great opportunity to try your hand at VLF CW reception either with a simple up-converter, direct conversion RX or even a software receiver totally implemented on a PC.