A WSPR first on 8.97kHz

This afternoon I set up my "earth-mode" station using a pair of electrodes about 10m apart in the garden, one near the house and one at the bottom of the garden. Using my 4W audio amp driven from the WSPR software in the PC I transmitted a WSPR signal on 8.97kHz. With a separate PC at the other side of the house and with 1m of wire as the "antenna" plugged into the mic socket of the PC I went listening for my WSPR signal.  Sure enough, there was my earth-mode transmitted signal at -15dB S/N. Distance was only about 10m but at least the TX, WSPR system and ground electrodes work, so I now can go out into the fields behind my house to look for my WSPR beacon using a decent, sensitive 8.97kHz RX next time. Strictly I need my sub-9kHz NoV to do this test, but as nothing is radiated I doubt anyone will care.

As far as I know this is the lowest frequency on which WSPR has ever been successfully used.

Sub-9kHz NoV application now with OFCOM

The application form and supporting data for my sub-9kHz NoV request are now with OFCOM. The very helpful and supportive man there, Rod Wilkinson G3TXA, says it has to go to the Met Office who need to give their approval. I'm expecting some weeks to pass before the application is, hopefully, approved. In the meantime I've started work on some equipment including a decent receiving system for 8.97kHz.

G3KEV considers 8.97kHz operation

One of the biggest signals, if not THE biggest, on 136 and 500kHz is Mal G3KEV up in Yorkshire. He has very large antennas and good equipment and has worked some very impressive DX on CW. Today Mal suggested he might also apply for an NoV to operate below 9kHz. This was his email to the LF reflector when he talked about what equipment he might use:

If I get time and a NOV for 9 kcs my proposed approach for TX would be an IC 706 on 900 kcs divided by 100/driver chip TC 4427 and a couple of FETS class D for an output of a few hundred watts, designed for 50 ohms, 50 ohm coax to antenna 200 feet away from shack as at present for 137 and 500 kcs.

Use the existing 1/4 wave inv L for 500 plus 2 additional ones same spec all in parallel and base loaded by inductor to resonate on 9 kcs, use existing ground radial system not too elaborate. Antenna height is approx 100 ft vertical and the rest to make up the 1/4 wave is horizontal.

The speculators, gamblers and dreamers might be able to guess what distance I might cover.

Let me compare your figures !!

Assume pwr to be 400 watts at base of antenna.

Using 9 kcs figure for convenience, but 8970 kcs would prob be the qrg

 I expect the experts on the LF reflector will come back with a probable range figure in QRSS100 shortly. It will be many hundreds of kilometres for sure.

More on the 8.97kHz DX by DK7FC yesterday

This is a combination of two screen shots showing the signal received in the UK (830kms!) and in Germany (180kms) from the 8.97kHz VLF test transmission by DK7FC.  The antenna was a kite supported vertical.  See http://www.qrz.com/db/DK7FC for more info and pictures. This was the email I got from Marcus DF6NM when I asked if the transmission had been definitely identified:

Dear Roger,

well, I think yes.

Attached are the two spectrograms from Paul (top) and myself (bottom), stretched to the same timescale 14:00 to 18:00 UT. The frequency was accurately as stated before, within a few milliHertz. This also was the first time I have seen a stable carrier, in a week since I started my grabber.

The indicated QRSS 120 message is only my guess of what Stefan might have started to send, before suddenly quitting. He had actually mentioned before that his generator might be running out of fuel sooner or later.

For receive, Paul used a pair of magnetic loops, with automatic beam steering for minimum noise. I have my LF Marconi, currently lowered to 3 m above the roof. The VLF signals are tapped off at the foot of the transformer coupled LF receiver input, using a 33 nF capacitor inserted into the ground line.

Best 73,

MArkus (DF6NM)

8.97kHz - REAL amateur VLF DX at last

As I write, the amateur transmission tests from Germany on 8.97kHz are ongoing, but it looks like the signals are being received in the north of England - a distance of many hundreds of kilometres. More in a few hours when details become clearer. If confirmed this will certainly be a new amateur record distance. The distance from Frankfurt to Todmorden is believed to be a staggering 830km  ...and this on 8.97kHz!!

New German amateur test on 8.87kHz planned

Stefan DK7FC is hoping to do a second test transmission on March 15th on 8.97kHz using a vertical antenna, new large loading coil and variometer. Transmissions should start around 1400z. Several stations will be listening and the DF6NM 8.97kHz grabber will be active. Stations possibly within range are DF8ZR (16kms) and  DD7PC (53kms).

8.97kHz does look like the new frontier!

8.97kHz VLF grabber on-line in Germany

DF6NM in Nuernberg, who has been successfully experimenting with sub-9kHz communications now has a temporary grabber on-air to capture any amateur signals on 8.97kHz.  See http://www.mydarc.de/df6nm/vlf/vlfgrabber.htm

Sub-9kHz induction comms resource

John F5VLF/G3PAI has brought a very useful website about induction mode communications below 9kHz to my attention. This site is mainly about cave location and beaconing systems, but there are some neat schematics for local coverage (thousands of feet range) TX and RX circuits that would be suitable for QRSS and similar experiments in the "Dreamers Band" as some have called it. See http://radiolocation.tripod.com/