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/

USA on 10m

At 3pm this afternoon KC2GMM was coming through on 10m WSPR at -25dB S/N when running 10W. Another example of the power of WSPR to spot the fleeting openings.

Realtime Propagation Charts

G0KYA has a most useful page offering realtime propagation predictions in the form of maps showing exactly where signals should reach on a given band at a given time of day. It uses the latest available solar data so should be a very good guide. The maps assume 100W and a dipole at medium height, so for a QRP station the results to be expected will be less good.

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.

Full QTH locator square? Find it here

Just discovered that my full QTH locator is JO02DG85VD . This was found using a website I'd not come across before http://no.nonsense.ee/qthmap/ .

144MHz WSPR

For the first time I tried WSPR on 2m this evening. G4IKZ at 18km was a VERY strong signal but with a huge amount of Doppler shift which meant he did not decode. I've just seen G4IKZ has spotted me at +3dB S/N though, so perhaps it was just a passing plane.

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.

8.76kHz field testing in the snow at 1.5km

With a temperature around 0 deg C I did a field trip today TXing on 8.76kHz VLF to test two things: (1) to check the rebuilt 4-5W TX based on the TDA2003 could be copied at moderate range and (b) to try out the new tuned preamp with earth electrode receive antennas and see how these compared with a loop. The usual first test site, a National Trust car park about 1.5km from home was chosen. Today it was totally deserted with more sensible people curled up in front of warm fires. Using the 80cm receiving loop or with the earth electrode antenna (electrodes placed about 13m apart) decent

copy was achieved in QRSS3, using Spectrum Lab this time rather than Spectran on the PC.  For the earth electrodes I just used barbecue skewers pushed in about 10cm into the very cold ground. Reception was also possible with the two earth electrodes just 2m apart. The first picture shows the signal received with a loop. The second is with the earth electrode antenna on receive. The ground was covered in a thin layer of wet snow and results when the soil, and soil surface, are dry should be better on earth mode conduction using earth electrodes at each end. The roads in the Fens were too icy to try reception at a more distant point 5-6km away. Also, I need a much longer baseline earth electrode pair in the car in case this is needed at greater range.