DK7FC/P active on VLF this Sunday

Stefan plans to be out with his kite antenna and around 100mW ERP on the VLF bands this weekend from 0700-1630utc transmitting on 3 frequencies starting with 8.970000kHz.  Progress can be monitored on his grabber located 40km from the /P location. I am hoping to copy Stefan on 8.97kHz again as I managed it back in December.

These grabbers will show when he is active:
8.97kHz http://www.iup.uni-heidelberg.de/schaefer_vlf/DK7FC_VLF_Grabber.html .
6.47kHz/5.17kHz  http://www.iup.uni-heidelberg.de/schaefer_vlf/DK7FC_VLF_Grabber2.html

DK7FC/P on 136.8kHz normal CW

DK7FC/P very strong on 136.8kHz CW today

Stefan has been out /P with his 100m long kite antenna, this time on 136.8kHz CW. He was excellent copy here in the UK (JO02dg) with a signal some 20-30dB over the noise floor even when sending fast CW. Attached is a screen shot from Spectran showing him working DF6NM at 1715 this evening. Distance is around 649km.

DK7FC's report on his 9th VLF experiment

DK7FC with his VLF loading coil

Stefan has summarised the results of his latest tests on VLF. This is well worth reading with best DX 2873km and lots of new stations receiving his transmissions for the first time.

This picture was taken by a friendly visitor and there are more pictures at http://mkorbit.de/2010/12/05/weltrekord-signalubertragung-auf-einer-langstwelle-vlf/

VLF real DX: 2873km on 8.97kHz

Yesterday, Sat Dec 4th, DK7FC's VLF signal was copied by 4X1RF at an astounding distance of 2873km. Signal levels suggest that transatlantic reception may indeed be possible in the near future. Many other stations also copied Stefan's signals on various VLF frequencies yesterday. Congratulations to Stefan and everyone else who managed to copy his signal.

DK7FC's 8.97kHz signal copied today (and in Israel!)

Weak signal around 8970.0Hz

Today I managed to weakly copy DK7FC's latest test transmission on 8.97kHz using my 20m spaced earth electrode and small FET preamp. Spectrum Lab, locked to a VLF MSK transmission helped by allowing me to look at precisely the right frequency. Distance is 648km. Stefan's signal was also copied in Israel, quite remarkable DX.

My VLF grabber on for DK7FC's tests on 8.97kHz

My frequency locked VLF grabber using Spectrum Lab software, running at QRSS600 speed (i.e. slow and narrowband),  is now active until Saturday evening in the hope I may see a trace of DK7FC's 9th VLF "kite antenna" transmission on 8.970kHz on Saturday. He will be using both QRSS and DFCW. He hopes to run up to 100mW ERP this time.

DK7FC on 8.97kHz this weekend

Stefan DK7FC is making preparations for a further test transmission on 8.97kHz this weekend. Saturday is his preferred day but if winds to support his kite antenna are too low, it may be Sunday. As usual, he will use very slow QRSS and DFCW.  During his last transmission he was received at 1310km and in a number of European countries.

Amateur VLF update: reception in 8 countries + 1310km DX!

DK7FC's summary of reports on Oct 23rd 2010

DK7FC has now summarised last weekend's test results on VLF (see table attached). His mW ERP signals from his kite antenna were received on 3 different VLF bands at distances up to an incredible 1310kms!
Stefan has certainly shown how to do it.

DK7FC's VLF tests a great success

Stefan's latest VLF kite antenna transmissions at 8.97kHz and even lower frequencies were a great success yesterday with reception as far as Eire, Italy, Poland and the UK. The attached shot shows the signal on 2 frequencies as received by Renato IK1QFK in Italy.

M0BMU receiving DK7FC's 8.97kHz signal 10dB S/N

Jim reports that Stefan's DK7FC's 8.97kHz test signal is visible at 10dB S/N in Tring UK this morning. He is also visible on other grabbers in Europe. This is an excellent report and further encouragement for those of us taking our first (QRP) steps on the 33km band.

Further 8.97kHz test this Saturday

DL7FC, Stefan, is planning another VLF kite antenna test this weekend Oct 23rd. I am assuming he will be on 8.97kHz again.

8.97kHz DX tests Oct 2nd 2010 (DK7FC)

Stefan's latest tests are going well with copy at 902km (Poland) and in Holland and the UK. His signal is stronger than ever before. Well done Stefan. Some stations right across Europe and even in North America are watching.

More German VLF radiated DX tests Sat October 2nd

From Stefan DK7FC:

Dear LF/VLF,

My next VLF kite experiment will be tomorrow, saturday, 2nd october :-) After my request to the german air traffic control i got a very kind telephone call at 01:30 AM and later i got the permission to go up to 200 m above ground. See attached mail if of interest for you.

So, if there will be enough wind and no rain, i will try to become QRV at arround  8 UTC.

Tomorrows program:

- (after some resonating tests): Transmitting a short message on 8970 Hz, mode: DFCW-600, hoping to be visible on several receivers in the EU region and maybe Canada and USA (!?)
- Transmitting a CW message (in 12 wpm and in 25 wpm), hoping to be audible at Bernd/DF8ZR (16 km range) and my grabber (40 km)
- Maybe trying a xband QSO 9kHz/144 MHz to DF8ZR
- Transmitting a message on 6470 Hz, mode: DFCW-600, hoping to be visible at many RX, especially Renato Romero who has set up a grabber page at http://www.vlf.it/cumiana/livedata.html
- Transmitting a 30 minute carrier on 8970 Hz which allows long time integration. Paul Nicholson wants to try to record the VLF audio stream from Florida and maybe extract my signal.

- Being visible at PA3FWM at the university of Twente who set up a grabber page at http://websdr.ewi.utwente.nl:8901/grabber.html
- Being visible at SQ5BPF and maybe a russian station?
- Being visible at Paul Nicholson and Markus/DF6NM, of course ;-)
- Finally reaching the 1 A antenna current limit
- and all i have forgotten

I will record my signal of my grabber and will extract an audible signal, if possible. This will be filtered, frequency shifted to 800 Hz and published here as a mp3 file.

My grabber will show the 8970 Hz signal at http://www.iup.uni-heidelberg.de/schaefer_vlf/DK7FC_VLF_Grabber.html
The 6470 Hz will be visible at http://www.iup.uni-heidelberg.de/schaefer_vlf/DK7FC_VLF_Grabber2.html

It is now on the Canadian and US RX stations to make possible what still seems to be inpossible: A transatlantic transmission/reception. The first time my signal can reach a 50 mW ERP limit (wind forecast announces strong wind, so a high kite angle, so a good efficiency!) on 8970 Hz. It is still not sure how the propagation behaves on this frequency at this time and locations so we may see a surprise. Of course any report is very much appreciated, no matter of what distance or country. Every clear reception above 859 km is a new world record by amateurs on VLF!

So, hope the sun will shine at good wind conds and low QRN and high interest :-)

Best 73, CU, Stefan/DK7FC

PS: Markus/DF6NM, will you be on the phone again to make QSP? :-)

VLF DX transmission with earth electrode transmission (49.6km)

DK7FC's 8.97kHz DFCW transmission received at 49.6km

Stefan DK7FC has informed me that he has successfully transmitted the message "CU" in DFCW on 8.97kHz to Michael Oexner at a distance of 49.6km. His TX puts out 250W into a 600m spaced earth electrode pair with a current into the antenna of about 0.5A. This is definitely far field reception. Stefan's earth electrode antenna is capable of further improvement, so he is expecting more successes shortly with it.

More sub-9kHz experiments

Just received this from Stefan DK7FC:

Dear LF/VLF,


Today i saw the first time a flag from Norway on my VLF Grabber (http://www.iup.uni-heidelberg.de/schaefer_vlf/DK7FC_VLF_Grabber.html). I would be very fascinated if my signal would be copied in LA/SM/OH  (of course, in all countries it would be very fascinating :-) ). Are there any stations, reading the reflector, from there who have the ability to receive on 8.97 kHz (or even 6.47 kHz) with a sensitive and stable RX frequency in DFCW-600 mode?
This would be one of my wishes for this period! One. ;-)
For this weekend i planned the next VLF experiment with the 200m vertical on 8.97 kHz but the wind forecast is not too promising :-( Maybe things look better tomorrow. I have to inform the air traffic control to give out a NOTAM (http://en.wikipedia.org/wiki/NOTAM), 48 hours befor i can start...
I will announce  tmw, if i will carry out the next test, if.
The signal would be once again the strongest i've ever radiated. About 50 mW ERP is the goal.
My planned tests for this year on VLF (kite antenna):
- CW QSO to DF8ZR (16 km distance) on 9 / 137 kHz
- Copying my signal on 8970/6470 Hz in Heidelberg in CW (40.0 km, audio recording and later analysis)
- Beeing visible in DFCW-120 in UK
- Beeing visible on the grabber of Renato Romero on 8970/6470 Hz
- Becoming QRV with the 300 m vertical antenna on 8970/5170 Hz, radiating 100 mW ERP at 8970 Hz
- Beeing visible in Russia and at all interested RX stations :-)
- Maybe a TA contact?
vy 73, Stefan/DK7FC *Dreaming...*

DK7FC's 6th VLF kite TX experiment

Stefan DK7FC is testing his 600W VLF transmitter into a 200m high kite supported vertical today (Aug 1st). He expects to radiate about 10dB more than in his last test (on 8.97kHz) and may transmit at a slightly lower frequency today (around 6.5kHz) depending on where the antenna is best matched. You can check progress on his grabber at http://www.iup.uni-heidelberg.de/schaefer_vlf/DK7FC_VLF_Grabber2.html .  Results from his last tests were amazing with reception across Europe in DFCW600 mode (dual frequency slow CW). For a summary of the reports (screen grabs) see http://abelian.org/vlf/ss100321/.  To copy his signal you will need a decent low noise/high dynamic range receiver (E-field probe or loop with preamp and filters) at VLF feeding into a PC running a package like Spectrum Lab, Argo or Spectran using narrow 3...5 mHz FFT settings and about 1 minute per pixel running speed. You also need to know precisely where to look, so calibration will be very important.

300m long kite antenna for VLF transmission

Stefan DK7FC has now received permission from the German authorities to use a 300m long kite antenna in daylight to transmit below 9kHz. With this antenna, 200m longer than his previous one, he should be able to run up to 16mW ERP which is 10dB more than when he lasted tested on 8.97kHz. A stronger signal should allow more stations to copy his signal.

Live 8.97kHz transmission from Germany

DK7FC is transmitting now (0800-1100z) on 8.97KHz. His signals are visible on his 8.97kHz grabber . Stefan is testing further improvements to his earth electrode antenna. The message is very clearly "73" sent in DFCW 600.

German VLF earth mode test: 5.2 km on 8.97 kHz

Stefan DK7FC has been doing some experiments with around 50W to a 300m spaced grounded earth electrode "antenna"  in a remote location in Germany. Today his experiments were successful with his transmission of 30 minutes clearly received on his E-field probe receiver and grabber located in the city some 5.2km away.  See the report on his experiments at  http://www.iup.uni-heidelberg.de/schaefer_vlf/VLF_5km_with_an_earth_antenna.pdf . Stefan can improve the electrode arrangement and increase current into the ground as well as run up to 500W. He's hoping to see the signal on the DF6NM VLF grabber located 174km away. If successful, this would be the first reported amateur radiated VLF DX using earth electrode antennas.

DK7FC's VLF PA

Stefan DK7FC posted the 300W PA used in his historic tests on 8.97kHz on the LF Reflector today. He's been copied by at least 10 stations in 5 countries using this PA with best DX 902kms.