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)

WSPR and 6m transatlantic testing

In a few months time 6m will start to open reliably for multi-hop sporadic-E propagation. This year, we have a new tool to help investigate really long distance openings across the Atlantic - WSPR. With enough WSPR stations both in UK and Europe and across the pond in W/VE and the Caribbean, we will have an excellent means of tracking transient openings at any time of the day or night. I for one plan to run my WSPR station almost 24/7 when not actually working live on 6m SSB and CW. I hope many others will join in the experiments.

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!!

10m open

Several Italians coming through on 28MHz WSPR this morning and giving me respectable reports with 1W into my halo. Not sure if this is sporadic-E or F layer. Also coming through around 11.30am was  the 5W WSPR signal from FR1GZ (Reunion Is) at -24dB S/N.

This afternoon another interesting exchange of WSPR reports with PC1CP 448kms away in JO33 square. My report was -24dB S/N with 2W to the halo and he was -17dB S/N with 5W. This distance is quite an odd one on 28MHz as it is too short for sporadic-E, so this was probably by tropo.

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!

85 unique reports now on 500kHz with 1mW ERP

With a report yesterday from PA3EGO, the number of stations who've reported my signal on 500kHz WSPR and CW has now risen to 85 so far since last September. It's pleasing to see new DX reports coming in despite the less effective antenna now in place i.e. the 10m halo and its 5m of feeder coax. I'm actually finding the reports are not that much down, if anything, on the top spiral loaded vertical.

iPOD - 1940s style

This was posted on the QRP newsgroup today. Wonderful idea.
http://www.retrothing.com/2010/03/vacuum-tube-radio-hat.html

VKs coming through on 10m CW

VK6DXI was a good signal (579 at times) in the BERU contest this morning on 28.006MHz CW. I called several times with my 5W QRP but did not get through. Conditions on 10m are on the up!

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

500kHz CW QSO this evening

For a change I went on 500kHz CW and managed to get a 579 report from Chris G3XIZ. Chris then went on to work PA0WMR although the Dutch station was only about 559 with me. I called him but he did not hear me.

Useful American sub-9kHz experimental VLF site

VLFradio.com is a most interesting site. Among the stuff there are the results of some induction communications tests with a 90m circumference TX loop out in the desert away from man-made interference. Using just 0.5W a range of 1 mile (1.6kms) was achieved at 1.8kHz and with higher power up to 2 miles (3.2kms). These signals were copyable by ear, so further still would be possible with weak signal techniques. Also on the site lots of recordings of these tests as well as other VLF noises and man-made transmissions

Another country using the "degraded" (?) 500kHz antenna set-up

As I mentioned a few days ago, I took down the main 500kHz vertical so I could re-erect the 28MHz wire halo with coax feeder. I'm using this, with feeder inner/outer strapped, as the antenna on 500kHz now. Actually the reports aren't much worse! This evening I got +1dB S/N from F6CNI which is a typical report from him at 418kms on WSPR.

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/

Sub-9kHz Induction Field DX?

With all the discussion recently on the LF Reflector about how to radiate a signal on sub-9kHz I'm left wondrering how far, practically, one could expect to get simply with sub-9kHz electromagnetic induction using multi-turn loops at each end.

It's quite easy for anyone to generate 50-100W or so and feed this into a largish diameter multi-turn loop. Correctly aligned and with a similar loop at the far end and using decent weak signal processing just what range might be possible using modes like QRSS or WSPR? Has anyone tried this to see just what is practical, simply using induction fields?

The Cave Radio Group (CREG) may have some answers but I'm not a subscriber so can't read any of their documents.

LATER: Jim Moritz M0BMU did some sums (see my webpage on sub-9kHz radio) and reckons that about 4.4kms is the best one could do with 100W and a 10m diameter loop and purely inductive communications. More power and bigger (low loss) loops could get a bit further still.

9kHz band receiver front-end (M0BMU)

Jim M0BMU has produced a neat loop/preamp design suitable for listening on the 9kHz band for which we hope NoVs will be available shortly in the UK. His design has sufficiently low noise to provide a state-of-the-art receiver for this band when used with the many excellent software based VLF receivers such as Winrad and Spectrum Lab. This circuit was posted on the LF Reflector this evening.

New African WSPR beacon coming

After successfully deploying the V53ARC WSPR beacon in October, OE1FM will have a second beacon system running in two weeks. 5X7JD (Uganda) has agreed to host a 1W WSPR beacon system at his Masaka QTH. See: www.oe1ifm.at

Whistlers!

This evening the VLF natural noise receiver in Todmorden, UK is buzzing with whistlers in addition to the almost continuous stream of tweeks. Whistlers are audible frequency descending tones caused by the dispersion of a lightning triggered impulse as it travels along magnetic field lines. At the moment I'm hearing about one whistler every 2 minutes.

Want a bigger 28MHz antenna?

Nick G4IKZ has just sent me this link to G0SXC's QRZ.com page showing his massive yagi for 28MHz. It has a boom length of 78 feet and a gain of 13.1dBd. Remember that each element is about 16 feet long, so you get an idea what a monster this is. I bet his neighbours must love him! This also explains why Kevin is such a consistent signal in East Anglia some 200 miles away.

10m tropo reception

Been on 10m this morning using WSPR at 2W. During the last hour  the 5W signal of G3JKV near Dorking has been received several times at a distance of 123kms. Although there's some aircraft scatter visible on the signal, I think this is mainly tropo propagation.

Sub-9kHz NoV application and German VLF tests

Later this week I hope to submit my application to OFCOM for a special research permit (NoV) to test at VLF frequencies below 9kHz. Things are moving on at a pace in Germany with several stations gearing up to carry out some serious radiated tests (i.e. not by induction or conduction) and some new DX records below 9kHz are expected to be set. There is a lot of  discussion on the LF reflector about antennas, loading coils, loops and elevated loops using grounded electrode pairs. See also my webpage on this at http://sites.google.com/site/g3xbmqrp/Home/10khz

814kms on 500kHz with 500uW, a 10m halo and 5m of coax

This evening my 500kHz QRP WSPR signal managed to reach DL3NDR despite the antenna system being "downgraded" yesterday: the spiral top hat has gone and in its place is the 28MHz halo with 5m coax feeder. ERP is I believe some 6dB lower at around 500uW, yet it still gets this far.

New amateur DX record below 9kHz (VLF) - 12.1kms

Markus DF6NM has reported on the LF Reflector that he's been able to receive his test transmissions on 8.97kHz at a distance of 12.1kms. See http://www.mydarc.de/df6nm/vlf/vlf_12km.jpg. He has calculated his ERP at 1.3uW into his relatively small antenna with 1.4 Henry loading coil. The TX was a 35W car-radio audio amplifier. His RX antenna was 6m long and he used SpecLab with very narrow effective bandwidth. There are several others now experimenting below 9kHz, so this new record may not last long, especially as Marcus was using relatively low TX power. OFCOM is considering the issue of NoVs for <9kHz in the UK.

More 500kHz tests tonight

This evening I'll be running the 500kHz WSPR beacon into the 10m halo and its feeder again via the ferrite rod. Last night the best DX was to Holland. ERP is probably around 500uW.

More 10m antennas

Nick G4IKZ tells me he is using a Eagle Antennas 10m Moxon beam (see picture from the Vine site of this antenna). These are available for £149 and claim just under 6dBi gain and 38dB front to back ratio with a wide beam pattern. They are only 3.8 x 1.52m which is small for a beam with this amount of gain. I suspect Nick may have turned his beam my way now as the signal report on WSPR when I was running 1W was a massive +3dB S/N. Before I put up my horizontal halo I was lucky to get much better than -20dB when running 2 or 5W.

500kHz TXing using the 10m halo

Having taken down the 500kHz antenna and put 28MHz wire halo back up I tried TXing on 500kHz with it. I strapped the coax feeder inner and outer together and fed it via the ferrite rod ATU with a bit more inductance. First report was from M0LMH some 223kms away at -20dB S/N , so I still get out OK on 500kHz with now <1mW ERP. Also getting reports from G6AVK at 78kms. At 8pm I also got a report from PA1GSJ, so the 28MHz halo and feeder makes quite a respectable 500kHz antenna!

10m halo re-erected

After the winter using my pole for the 500kHz antenna, I've now replaced the 500kHz spiral topped wire with my Homebase-10 halo antenna for 28MHz that appeared in PW a few years back. Using G4IKZ 18kms away to receive my WSPR signal, I see the reports leapt up by at least 14dB, so it is certainly working well. I shall try the antenna and feeder (strapped together)  this evening to see how it performs on 500kHz. I'd expect it to be some 10dB down on the original 500kHz antenna.

10m tropo?

WSPRing on 10m this lunchtime I've been receiving G3JKV over a distance of 123kms. There is no sign of aircraft flutter on his signal, so I wonder if this is by tropo? He is, like me, only running QRP and this again illustrates how useful WSPR is at "winkling out" fleeting openings. I'll be swapping back to the 10m halo shortly.

USB powered direct conversion RX

G1INF has a neat idea on his blog for a simple direct conversion RX that is powered from the USB connection of a PC. His application was for LF reception but it would work equally well as the front end of a simple SDR for any HF band, replacing the loop with a bandpass filter. The audio output from the NE602 is connected to the PC's mic connector. Simples!

UK on-line VLF Receiver

There is an on-line VLF receiver on which you can hear natural emissions such as sferics, tweeks and whistlers located at Todmorden in the north of England. As well as a real-time audio stream, it has an interesting way of plotting received signals so you can see the direction of arrival of sferics.

Fivehead QRP SSB transceiver kit

This afternoon Ted G4NUA came around to test the receiver section of his Fivehead 20m SSB transceiver kit from Walford kits in Somerset. I was surprised how small the transceiver was. We checked the RX with a signal generator and re-did the alignment. We then tried it on an external antenna and it was about the same sensitivity as the FT817 and was copying plenty of stations on 20m SSB. Ted has still to finish the TX part. When done it should put out about 1.5W pep.

Warm sunshine and G3XBM up a tree

Today the sun has been shining and it's quite warm so I've been up the neighbour's tree lopping branches so that they don't obstruct the light. It is a field maple and it grows so fast. I took down branches about 4 metres long and these have grown in the last 3-4years. There is also a method in my madness: there's a sturdy branch just the right height to act as a support for the end of my longwire. It's twice as high as the original on the clothes line support. So, when the job is done I'll string out some black PVC covered wire. Also, for the first time this year I managed a cup of tea on the patio: maybe spring really is almost here at long last.

11th country on 500kHz

Just had a 500kHz WSPR report from MW0CVT 250kms to the west of me. This is now my 11th country from which I've had reports on the band. This is also my 83rd unique report on the band.

Amateur DXing below 9kHz (VLF)

Some recent discussion on the LF Reflector is suggesting that distances of >100kms should be workable with amateur stations below 9kHz, albeit running QRO exciters. This would be possible with optimised stations and antennas and very slow QRSS modes. As an example, see the email posted this evening by RA9MB:

I was wonder if it is posible to use a loop on 9 kHz. Serious problem to radiate 9 kHz is high voltage we saw. Loop has that advantage that voltage is not too high. Then i do some estimations. Let's assume vertical loop 15m x 50 m with 20 mm diameter coper tube as a wire. Then effectivity of such a loop on 9 kHz is about -65 dB. It is adequate to radiate 1 mW
on 9kHz (I=250A, TX power about 4 kW). We saw such a radiation should give abt 100 km  distance in QRSS. Besides such a loop is well suited for 136 kHz. On 136 kHz it effectivity should be about -25 dB. Not too bad: 1 W radiation with 400 W TX :-)

QRP transatlantic on 80m

Just got a report from W1XP on 80m WSPR when running just 1W into the 5m long vertical. DX is 5280kms. Report suggests that 500mW would also have crossed the pond.

New Zealand gets 500kHz (for now)

From March, New Zealand amateurs will be allowed to use 505-515kHz. The number of administrations making temporary allocations is increasing all the time now. Expect some ZL-USA (and maybe Europe?)  tests before long on the band. I wonder who will be the first to receive some 500kHz WSPR beacons from the Antipodes?

Australia on 40m QRP tonight

It really is too easy with WSPR on HF.  Last night some reports from Antarctica and tonight a brief 5W transmission on 40m got me another report from VK6POP in Australia. One of my projects is a micropower WSPR beacon for 10m, but it will have to be something like 10mW to be anything like a challenge :-)

First sub-9kHz NoV application with OFCOM

G7NKS has already submitted his application for an NoV to operate below 9kHz. Mine will be prepared in the next few days. Approval (or rejection) may take some time as OFCOM has to consult with the Met Office first. The Met Office monitors <9kHz for sferic activity to track storms and lightning.

WSPRing to Antarctica on 30m

This evening my 30m WSPR signals got to Antarctica with several reports from the German Research Station DP1POL in IB59 some 13690kms to the south of me. Best report was -18dB S/N suggesting that I would have been copied running just 500mW.