31 Dec 2010

VLF success at last for G3XIZ (37km on 8.97kHz)

Chris G3XIZ achieved some VLF success today when his 50m high balloon supported vertical driven with around 50W was copied at up to 15dB S/N by M0BMU at a distance of 37km. Mode used was QRSS600. This is a new UK record for an amateur VLF transmission and is the first confirmed "far field" radiated signal. Well done Chris.

M0BMU estimated the ERP as follows (from a posting to the LF-reflector by Jim):
"I made an estimate of the field strength of your signal by injecting a test signal at a known EMF into the loop antenna, and comparing with the level of your signal. The received FS at the strongest point (around 1330utc) worked out to be 1.8uV/m. Taking the distance between our locations as 37km, your ERP would have been 87uW. The SNR at best was around 15dB, making the noise level 0.32uV/m in the FFT noise bandwidth of 2.1mHz, or a noise density of 7uV/m per sqrt(Hz)


Assuming a 50m vertical wire (heff ~ 25m),  Rrad of your antenna at 8.97kHz would be 880micro-ohms. Assuming 2.62dB directivity for an electrically short monopole compared to a dipole, and Iant of 200mA, the calculated value of ERP would then be 64uW. So there is reasonable agreement between these two calculations, the difference only being 1.3dB."

29 Dec 2010

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

28 Dec 2010

Diurnal Variation in Dreamer's Band Noise

Over the next 24 hours I am doing a test to measure the change in VLF noise floor between 0-24kHz. DK7FC has let me have a suitable .usr file for Spectrum Lab to allow this to be recorded. You can see the results on the G3XBM VLF grabber which is updating the plot every 15 minutes.

Surprise late afternoon 10m opening to the USA

WSPR reports 10m on 28.12.10
Late this afternoon I was surprised to see that 10m opened up to the USA and that my QRP WSPR beacon was being received well at up to 6991km with reports at 5692km from K3ZV as late as 1800z with my reports of USA stations being the last ones to appear, meaning I was receiving stations when others were no longer doing so. Power was 5W and the antenna the Homebase-10 wire halo.

27 Dec 2010

G3XIZ on 8.97kHz today

Chris, G3XIZ was testing on the Dreamer's Band again today and I was monitoring some 34km to the east. Unfortunately, this attempt was also unsuccessful with no copy here in East Cambridgeshire.

Iceland get big 500kHz allocation

493-510 kHz has been granted on a secondary basis to amateurs in Iceland with a power limit of 100W. In addition, 60m and 4m allocations have also been confirmed.

26 Dec 2010

Dutch hams lose 500kHz (for now)

Stations in The Netherlands who were active on 500kHz will have to stop transmitting at the end of 2010 as their permits have yet to be renewed. It is expected that this will happen within 4-6 weeks.

25 Dec 2010

Christmas WSPRs

Very quiet on 10m WSPR today, Christmas Day. Just G3JKV coming through from 123km to the south of me on tropo. WSPR is an ideal mode for Christmas day as one can set it running, go eat the turkey and trimmings and periodically check results.

24 Dec 2010

Merry Christmas everyone

Whatever your circumstances I hope you have a peaceful and happy time this Christmas shared with the people you love.

22 Dec 2010

G3XDV on 136kHz QRSS

Getting a very strong signal this evening from G3XDV on 136.177kHz QRSS60 receiving Mike on the earth electrodes fed straight into the deaf (at 136kHz) FT817. He is sending "XDV" preceded by G3XDV in normal speed CW.

19 Dec 2010

160m QRP DX on WSPR

WSPR reports - 160m 5W QRP
Last night I used my 5m long vertical feeder to the 10m halo as a TX antenna on 160m WSPR, matching it with a few turns on a ferrite rod on the bedroom table and the Elecraft T1 auto-ATU. Results were very encouraging for 5W and an indifferent antenna with best DX reports from Norway and Spain. On RX the best DX was RA3LW at 2036km.

18 Dec 2010

160m DX on WSPR

Last night I decided to take a look on 160m WSPR to see what could be heard/seen with my strapped feeder up to the 10m halo as an (untuned) vertical. 21 unique stations copied and best DX was K9PAW (running 2W) at 0222z who is 6370km away. I may now try some overnight TXing with this antenna properly tuned and matched to see how far away my own QRP WSPR signals can be heard.

17 Dec 2010

13cm handheld "DX" QSO

My iPod Touch 4g has the free Echolink app installed and last night, when I went to bed, I decided to give it a try. I managed to work a mobile station in Brisbane, Australia using the Brisbane repeater. In effect, the iPod Touch is used as a 13cm QRP handheld transceiver (using the 802.11 wi-fi functionality). Fun, with simple operation and good audio reports. I continue to be amazed by the iPod Touch 4g which is a truly amazing piece of kit for around £160. There are very many useful amateur radio applications including a free oscilloscope and audio spectrum analysers and spectrograms for a few pounds only.

16 Dec 2010

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!

Long duration VLF test on 8.7608kHz yesterday

Yesterday I ran my 5W 8.7608kHz beacon into the earth electrode antenna on a quasi-continuous basis with transmissions of 30-60 minutes interspersed with 30-60 minute breaks. The tests lasted from 0900-2200z. Several stations between 25-70km were looking for my signals and Paul Nicholson up in Yorkshire has still to analyse his recorded files. So far, no station has detected any sign of the signal, which was not surprising considering the radiated ERP would have been in the pW level.  I was hoping that a few stations 10-20km  from JO02dg might have been looking as these would have had some chance of copying something. So, an unsuccessful test this time.

Paul Nicholson (Todmorden) advises me to use a GPS locked source so that the TX frequency is known with great precision. Then he, and others, can look for statistically significant weak signals at precisely the times and frequency of transmission. My HF crystal and divider source would not have been sufficiently stable to allow this sort of "digging in the noise" over any great time period.  For QRSS3, the current stability is fine. For the record, these were my transmission times: 0840-1000z, 1029-1229z, 1330-1500z,1531-1600z, 1630-1800z, 1830-1900z,1930-2207z on 15.12.10.

Yaesu FT450D (new version of the FT450)

Stateside magazines and websites are talking about a new version of the FT450 from Yaesu.  See the Universal Radio page about the FT450D. Apart from differently styled knobs and a couple of fold down feet - the original did not have a stand - I cannot really see what has changed. The FT450 has consistently got good reviews as a relatively inexpensive 160-6m 100W rig. As someone who has always been very pleased with Yaesu products right back to the FT7 days, I would consider this if buying a new HF radio for general use.

CamBeam Dec 2010

The latest edition of CamBeam the magazine of the Cambridge and District Amateur Radio Club (CDARC) is now available giving notice of future club activities and projects and of the upcoming AGM.  Currently I am a lapsed member of the club, although back in the early 1970s I was very actively involved when I first came up to Cambridge.

14 Dec 2010

10m transatlantic F2 propagation today

Just got a -7dB S/n report from N4AU on 10m WSPR at a distance of 6976km. I believe this is my first 10m F2 report in many years. Not a bad report for 5W as it suggests the signal would have been copyable with about 25mW.

12 Dec 2010

VLF very long carrier period tests Dec 15th

This Wednesday, Dec 15th, I will run tests on 8.7608kHz with very long continuous TX periods of several hours interspersed with gaps of 0.5 to 1 hour. Transmissions will start at 0900GMT and finish at 2300GMT. I will reveal the TX pattern after the test so the test is done "blind".

I'd be most grateful if suitably equipped stations could look for any possible signs of the signal, even though I shall only be using the 20m spaced earth electrodes and 5W as used for my local earthmode tests. Those able to screw the bandwidths right down may just be able to detect something, although I think it is unlikely at any great distance.

15.12.10    
0900-2300z 
8.7608kHz   
Carrier "on" periods of 30mins or more

Good luck to anyone having a go.

73s
Roger G3XBM

--

10 Dec 2010

How far is possible with earth mode on the Dreamer's Band?

A further observation from the test today: with 17dB above the noise signals at 5.1km using QRSS3 there is plenty of (theoretical) range still to be had with utilities assisted earth mode and just 5W.

Assuming 18dB loss every time distance is doubled (an inverse cubed attenuation rate for induction/conduction - is this right?) then almost 10km should be just possible, assuming the utilities that are aiding propagation are still there in the ground. Going from QRSS3 to QRSS30 should give another 8-10dB (see http://www.qsl.net/on7yd/136narro.htm#QRSS). Increase power from 5W to 100W gains another 13dB, so QRSS30 and 100W could give a range of some 20km by utilities assisted earth mode in favourable locations.

So, in some locations using the utilities buried in the ground all around us could offer some quite decent ranges with an earth electrode "antenna" at the TX end that requires minimal matching and no large loading coils, just a step-up transformer.

What is less clear to me is what exactly is the signal being carried along? Water pipes (often these are plastic now), overhead mains cables, gas pipes (usually non-metallic), phone lines, rivers even?

8.76kHz tests with loop + earth electrodes on RX

Today I did a test at 5.1km to compare reception of my 8.76kHz 5W transmission using (a) an 80cm loop antenna and (b) a small earth electrode antenna (14m spacing) using a variety of preamps.  Although quite solid reception (17dB S/N in 0.18Hz BW) was achieved using the loop laying flat on the ground, there was absolutely nothing detected using the earth electrodes, which was both surprising and disappointing. I used the very same preamp in both cases and also tried the lo-Z input tuned preamp with the earth electrodes that successfully copied DK7FC at 648km last weekend.

Several possibilities for the failure with the earth electrodes:
  • The electrode spacing was far too small
  • The barbecue skewers used as electrodes were too short and not making decent soil contact
  • The soil was too wet, so the pick-up was lower than with dry, low conductivity soil. The test site is in the fens where the soil is a dark peat.
Next step is to repeat the test up on the chalk uplands to the south of the QTH where soil conductivity will be lower and to try a larger earth electrode spacing on receive.

9 Dec 2010

A Homebrewer's Lab

VU2ESE's workbench - not unlike mine!
Ashhar Farhan VU2ESE has an interesting page setting out what basic equipment he considers a QRP homebrewer needs. See http://www.phonestack.com/farhan/lab.html. The only additional piece of equipment that I have found really useful is a small box to measure inductors and capacitors. The LC Meter kit produced by the Cambridge and District Radio Club has proved invaluable. A small spectrum analyser would also be useful, but these do not come cheap, although there are designs on the internet to make simple ones.

8 Dec 2010

500kHz WSPR with earth electrodes

This evening I tried WSPR on 500kHz again using the earth electrode "antenna". 4 different stations reported hearing my sub 1mW ERP signal with best DX 417km to PA0A. Tomorrow I may try 500kHz with the vertical antenna to see how it compares, although I have to rebuild the ATU first.

7 Dec 2010

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.

6 Dec 2010

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.

5 Dec 2010

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.

4 Dec 2010

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.

3 Dec 2010

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.

2 Dec 2010

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.

1 Dec 2010

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.

28 Nov 2010

New front-end for 8.76kHz VLF earth mode tests

Today I completed the design of a new "front-end" for my tests on 8.76kHz when using earth electrodes as the RX antenna. Up to now I've used an 80cm loop/preamp at the far end of the test, usually with the loop on the ground for maximum signal pick-up. Now I want to compare results with an electrode pair antenna at the RX, laid across the road to form a pickup loop within the ground around any buried pipework and cables. The electrode pair is about 30-100 ohms, so I needed a low input impedance. I decided on a grounded gate FET amplifier with a simple LC tank circuit in the drain tuned to 8.76kHz fed via an emitter follower into the PC sound card. It has sufficient selectivity to reject 50Hz and lower harmonics and reject the stronger VLF and LF stations which could cause intermod and overload. I've also added a small LC lowpass filter on the input to the FET. This will be field tested at a site 5.3kms from the home QTH as soon as the weather improves: it is currently below freezing day and night!

25 Nov 2010

Receiver/grabber improvements on VLF

Just received a special build of Spectran from Alberto I2PHD that keeps the same filename for captured grabber images. This means I can now use Spectran with my VLF grabber. This is fired up from time to time when people are doing VLF tests. It will also allow me to look for my own signal at home when I am out transmitting in the Fens locally some kms from home. I find Spectran easier to use than Spectrum Lab, which is a clever program but complicated for someone like me to configure.

I have also rebuilt the 4-5W beacon TX on 8.76kHz and given it a 1 hour continuous soak test. There is a video about this on my YouTube channel.

My next job is to work on a permanent VLF E-field probe outdoors and to make improvements to the receiving system for field use. I need a better preamp/filter that can also be used with earth electrode receiving antennas as well as the loop and E-field whips.

22 Nov 2010

Looking for G3XIZ on VLF this evening

G3XIZ is transmitting with 20W to his Marconi vertical on 8.9719kHz this evening from 2000-2200z. I am looking out for his signal with my loop into both Spectrum Lab and Spectran software. You can look on my VLF grabber to see if he is visible at all over here in JO02dg. At the moment all that is visible is a wobbly 50Hz related signal and my 8.760kHz QRSS3 beacon running on a dummy load. UPDATE: nothing copied and Chris had to close because of an antenna fault at 2100z.

21 Nov 2010

VLF Grabber operational capturing 8-9kHz in JO02dg

I'm setting up a VLF grabber at my home QTH to take periodic screenshots of the 8-9kHz Dreamers Band and make these available online. At the moment it is taking input from my earth electrode "antenna" into Spectrum Lab and is very much a work in progress and needs a lot of improvements on the RX and antenna front. It won't be ON unless I'm in the shack and don't need the PC for other VLF stuff.  

The resulting screen grab every few minutes appears at
https://dl.dropbox.com/u/15047843/xbm_grab.jpg . 

VLF Grabber

Today I intend to make a VLF grabber to receive sub9kHz signals and automatically upload the screen grabs to the Internet. My aim is to use Dropbox as the place where the grabs will we stored and visible.

19 Nov 2010

6 Spanish stations get access to 501-504kHz

The Spanish authorities have granted limited access to 501-504kHz (100Hz bandwidth, 5W) to 6 stations (EA1AY,  EA2HB,  EA3CC,  EA3WX,   EA4BVZ, and  EA5DY) until the end of May 2011,

16 Nov 2010

iPod Touch 4g

Recently I upgraded my pocket PC - I used a Dell Axim for 7 years - to a new iPod Touch 4g purchased at a good price from Amazon. It really is an amazing piece of kit in a tiny size with an incredibly pin-sharp screen which is so good that individual pixels cannot be seen: the resolution is better than my TV. I've already downloaded the Echolink app (free) so I now also have a 2.3GHz pocket ham transceiver too. I hope to use it for some other ham radio applications including datamodes and VLF reception.

If you want to see what is inside the iPod Touch 4g look here for a tear-down analysis: there is a lot in this small package!

14 Nov 2010

First Norwegian VLF amateur transmission

From Jan LA3EQ:
"First succesfull transmission on 8.760kHz using WSPR mode in Norway using 40 meter longwire and only speaker output from the pc soundboard as a transmitter and a 12volt to 220v transformer as impeadence "antenna matching" transformer..  Several WSPR spots of -2dB to -7 dB. distaince only 50 meters, but it is a start. Next try will be with earth dipole and 10 watts and an active e-probe antenna on receive."

VLF kite transmission by DF6NM

DF6NM's signal in the UK
Marcus DF6NM carried out another successful VLF test yesterday on 8.97kHz (200uW ERP) and 6.47kHz (50uW ERP) with reception by Paul Nicolson in Todmorden UK.  Marcus is the second German VLF amateur to be copied at this distance.

12 Nov 2010

Inactive week radiowise

This week I've been very inactive on the radio because we have had our grandson's 3rd birthday party here with his French grandparents (neither of whom speak English) staying along with his mum and dad. Still, a lovely time was had and he got lots of nice presents. By the way, he now knows the difference between square waves and sine waves and loves going "oo oo", which means fiddling with the audio oscillator and scope.

7 Nov 2010

Looking for G3XIZ on 8.9719kHz VLF

Looking for G3XIZ on 8.9719kHz - maybe a faint trace??
Between 2000 and 2200z this evening G3XIZ has been transmitting on 8.9719kHz VLF with his Marconi vertical and about 20W RF into it. I've been monitoring with my earth electrode antenna, a preamp/filter and a PC running Spectran on 0.17Hz resolution, but don't think I've seen any sign of him.

5 Nov 2010

Real QRP on 8.760kHz today

Weak trace at 1.5km from the 320mW TX by earth mode
320mW 8.760kHz QRSS3 transmitter
Having blown up my 4W transmitter yesterday I built a smaller QRSS3 beacon TX today that puts out 320mW into 50 ohms. I connected this to the earth electrode antenna and went out with the loop and E-field probe and PC to see how it performed. The signal was copied weakly but solidly at 1.5km away at the local National Trust carpark (see picture from Spectran showing the XBM part of may callsign). An attempt at 5.1km was unsuccessful although faint traces of the line at 8.760kHz may have been visible.

How to be stupid ...follow me

Just managed to blow up my 8.76kHz TX by putting the supply the wrong way round: took out the 4060, 5-Vreg and several electrolytics.The TDA2002 was also damaged. Rebuilt the keyer and freq gen part OK but now need to source a new audio PA IC or module. Now I have a reverse protection diode across the pins! You learn the hard way.

In the meantime I may try even lower power with my trusty 2N3904/3906 1W PA and see if this can be seen at the NT carpark (1.5km) and at Lord's Ground Farm (5.1km). Also, as this PA is efficient and runs cold for ever I could try 1 day on, 1 day off, QRSSSSS and see if more distant people could copy it using very narrow bandwidth reception as per DK7FC's tests.

4 Nov 2010

QRP at AA1TJ

It's time to remind people of the wonderful circuits and ideas at Mike Rainey AA1TJ's site. Always full of amazingly simple designs that really work. See  http://www.aa1tj.com/radio.html

3 Nov 2010

UK first transmission on the Dreamer's Band (8.760kHz)

Signal received at 5.1km from home QTH on 8.760kHz VLF
This morning 0915-1115 GMT I transmitted a QRSS3 beacon signal on 8.760kHz under the terms of my NoV recently received.  I think this is a first in the UK, legally at least.

8.76kHz TX
TX was 4W from a TDA2002 audio IC matched into earth electrodes 20m apart. The beacon signal was provided by a K1EL keyer chip and the frequency reference by dividing down an HF crystal by 512 times in a 4060 divider IC. Reception was possible 5.1km away from the transmitter location, detecting the signal with an 80cm loop fed into an E-field probe (Hi-Z input) into Spectran running on a WinXP PC. Best reception was always with the loop flat on the ground suggesting the main mode of propagation is utilities assisted earth mode. Comparing results on 8.76kHz with those at 838Hz earlier in the summer, my first impressions are that signal levels are some 6dB weaker, but more careful tests will be needed.

2 Nov 2010

500kHz interference

In the last few days several stations across Western Europe have noticed a strong wideband signal that is severely impacting reception between 498-502kHz. This appears to be a NATO test transmission for a marine data system that may be introduced in the near future.

8.75kHz VLF transmitter ready

My small 4W, crystal stabilised, 8.750kHz VLF transmitter is now ready to test having fitted the crystal and 4060 divider this morning. All being well I'll test this Wednesday or Thursday when I've optimised my soundcard settings on the PC used at the RX end.

1 Nov 2010

Preparations for Dreamer's Band Tests

This evening I modified my loop antenna and VLF preamp to better optimise them for use at 8-9kHz and also modified my E-field probe antenna. So, on the RX side I think I'm ready with the hardware. By Wednesday I hope to have the 4060 divider behind the HF crystal to give me a stable 8.750kHz source for the TX. If the weather is reasonable I should be out testing in the Fens locally by Wednesday or Thursday.

28 Oct 2010

First "Dreamers Band" UK test next week

As is required by my NoV, I asked the Met Office for permission to transmit in the 8.7 - 9.1kHz band next week Tuesday to Friday 0800-1800 GMT and they've confirmed it's OK.

My initial tests will be a repeat of the earth-mode tests done at 838Hz earlier in the summer using the same kit  with 4W to 20m spaced earth electrodes. I'll also test with the 70m sq wire loop antenna used for 136 and 500kHz. The most likely TX frequency will be 8.750kHz (4.480MHz xtal divided by 512). I'll find a means of getting on 8.970kHz later. Modes will be 12wpm CW and QRSS3 initially.

These local tests are not in the same league at all as DK7FC's and I'm only expecting a few kilometres at best. However, it is a start and it allows me to test TX and RX equipment and different PC packages.

27 Oct 2010

6 countries on 500kHz tonight

Another good night on 500kHz WSPR with several more reports from Finland (OH1LSQ) as well as a report from Norway (LA3EQ) and several from nearer countries. ERP still in the 1-2mW region from the loop antenna.

Protecting power grids from solar storms

NASA Science News reports:
"Every hundred years or so, a solar storm comes along so potent it fills the skies of Earth with blood-red auroras, makes compass needles point in the wrong direction, and sends electric currents coursing through the planet's topsoil. The most famous such storm, the Carrington Event of 1859, actually shocked telegraph operators and set some of their offices on fire. A 2008 report by the National Academy of Sciences warns that if such a storm occurred today, we could experience widespread power blackouts with permanent damage to many key transformers."
There are plans afoot to create an early warning system to protect the US grid system in such events.

26 Oct 2010

More DX reports on 500kHz

Log from early evening Oct 26th 2010 (500kHz QRPp WSPR)
This evening, the QRP 500kHz signal from the small vertical wire loop is doing well with reports again from Finland on WSPR. I still can't quite believe how a loop of thin wire with part of it sitting in the wet grass can work so well with so little power applied to it.

Stable, simple, stand-alone, 8.970kHz source?

What do people think is the simplest way of generating a stable 8.970kHz (kilohertz) frequency that does not require a PC when running? I thought of an HF crystal divided down by 256, but have you tried to buy a "made to order" crystal lately? I need this for my VLF tests this coming winter.

Vertical loop versus earth electrodes antenna

Just done an interesting test comparing my vertical wire loop with an earth electrode antenna. I removed the lower part of the loop and connected the ends to ground. Matching was totally different (low Q antenna) but the performance was only 5dB down on the loop, based on reports from 2 local and one DX station. A similar test on 136kHz as the only station on in range (M0BMU 69km) was unable to copy my signal on the earth electrode antenna suggesting at least 5dB down on that band too.

25 Oct 2010

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.

136kHz ERP

A fairly easy way to increase my ERP on 137.5kHz WSPR is to up the supply voltage to the IRF510 PA. Using a 20-24V supply I was able to get another 3-4dB ERP judging by the reports from M0BMU and G3WCD this morning. This evening I'll give it a go with the higher supply to see if I can get any reports from further afield. I've also thickened up the bottom part of the loop which will reduce the resistive losses by about 15%.

24 Oct 2010

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

23 Oct 2010

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.

22 Oct 2010

More 500kHz 2mW ERP DX reports this evening

This evening I switched back to 500kHz from 137kHz WSPR earlier in the day. Yet again good WSPR reports from GM4SLV and OH1LSQ (1733km) who received me as early as 1716z.

8.7 to 9.1kHz NoV received

This morning I received my NoV from OFCOM to operate legally around 9kHz (see copy on RHS - click to enlarge).

Details are:
  • 1yr duration
  • 8.7kHz - 9.1kHz 
  • 100mW EIRP
  • Modes not specified (long periodic modes preferred by Met Office)
  • Met Office have to be informed of, and approve, operating periods and be sent logs
  • Home QTH or /P locations only with prior Met Office approval
No firm plans yet when I'll start local tests on this band, but within couple of weeks with QRP WSPR and QRSS. I'll put a copy of the NoV on my website in the next few hours.

21 Oct 2010

Struggling on 137.5kHz

Using the same TX output power (5W) and the same loop antenna I'm finding life is VERY much harder on 137.5kHz compared with 500kHz. Last night I was being copied right across Europe on 500kHz but tonight only 2 stations (best DX 69km) are able to copy me on 137.5kHz WSPR. The reason is simple: the radiation resistance is so much lower, so losses become more significant, and the ERP is very considerably lower. There is no doubt that to increase my "sphere of influence" on 137.5kHz I'll have to make some big improvements.

20 Oct 2010

New DX record on 500kHz WSPR

This evening, quite unexpectedly, I got a string of reports on 500kHz from OH1LSQ in KP03sd at an astounding distance of 1733km. To me these are amazing reports pushing my best DX on the band with just a few milliwatts ERP to new levels.  What surprises me is how well a very simple wire loop works as a TX antenna: the wire is just 1mm diameter, with a loop area of around 70m square with part of the loop on the ground buried in wet grass. I now believe almost anything is possible!

Vertical loop success on 500kHz QRP

This evening I've been WSPRing on 500kHz running about 2mW ERP from my thin vertical wire loop with an area of around 70 sq metres. The bottom of the loop just runs along the ground and at the moment is buried in the long wet grass! Despite this, my signal is being decoded in G, ON, PA and GM with best DX tonight 896km to GM4SLV up in the Shetland Is.

19 Oct 2010

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.

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.
 

Holiday in South Africa - just back

No posts here for the last few weeks as my wife and I had been on holiday in South Africa. It was an amazing holiday organised by Saga and we saw some fantastic places, people and animals. Saga organise holidays for the over-50s and we were not sure what to expect, but the hotels, food, transport, and everything well exceeded expectations and the group we were with was a real mix of interesting people. The whole experience was something to feed on for years to come. For example, seeing the "Big 5" wild animals (and many more) in the Kruger National Park, seeing no less than 6 southern right whales at one spot from the shore near Cape Town and getting to within a couple of metres of wild penguins on a beach near Simonstown. Also, seeing the highlands of Lesotho where people still live a subsistence existence in huts made of dung, straw and sand without electricity and the basics we take for granted.

2 Oct 2010

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.

1 Oct 2010

10m WSPR DX

For a change I went onto 10m WSPR today and was rewarded with a -26dB S/N report from FR1GZ on Reunion Island (9724km away) when I was running 5W to the halo.  Interesting to note the Doppler shift on the signal (and also on the signals from FR1GZ) which suggest movement of the equatorial F layer.

Earlier in the afternoon ZD7FT was a reasonable signal on 10m SSB from St Helena and there were several VE and W's on 15m SSB.

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? :-)

30 Sep 2010

More reports wanted on 137kHz WSPR

Continuing to beacon close to 137.467kHz WSPR with about 20uW ERP and getting regular reports from M0BMU (69km) and occasionally others when active. I'd appreciate more reports. It would be interesting to know if others further away can see the occasional 2 minute WSPR burst, but possibly not decode it. 

137kHz receive challenges

Several people have emailed me about receiving signals on 136/137kHz. Now I'm certainly not greatly experienced in this, but a few things I've picked up from others are worth passing on:
  • Many HF rigs are deaf on 136kHz, for example the FT817, although this is less deaf if you switch IPO to "on" on 136kHz. A small preamp may help as long as this is selective and doesn't increase overload and intermod from strong out-of-band stations. 
  • The receiving antenna may have to be directional e.g. a small loop/preamp to allow local noise sources to be nulled. 
  • DCF39 on 138.830kHz sending FSK data with a burst every 10 seconds is a good indicator of receiver performance: it should be a good strong signal in the UK. 
  • Ultimately it is S/N rather than noise figure that matters on this band.
  • Be prepared to use PC software such as Spectran or Argo to look for weak QRSS mode signals.
Here, I'm using the deaf FT817 (no preamp) with my 80sq m transmitting loop facing W-E at the moment and this is able to receive G8IMR's 20mW ERP WSPR beacon most of the time (188km) despite not being in the main direction of the loop. I've also copied G3XIZ, G3XDV, G3YXM and G3KEV on the band, the last being on CW. So, even a poor receiver can produce results, but it is really worth optimising the set-up (including here at G3XBM) to get more decent results. This is on the agenda.

28 Sep 2010

VE7-JA QSO on 136kHz

JA7NI and Scot VE7TIL completed a trans-pacific QSO on 136kHz this morning, a first between Canada and Japan.  DX is 7162km. This was the result of many months of hard work and planning and followed several previously unsuccessful attempts.

7th new reporter on 137.5kHz WSPR

M0BMU copied my 137.5kHz QRP WSPR signal today giving me -19/-20dB S/N, which is quite a good report. Distance is 69kms. This is now the 7th unique station reporting my WSPR beacon. I'm still hoping for a report from outside of the UK soon, but suspect I'll have to increase the ERP beyond the current 20uW level to achieve this. The consistent signal report from Jim should allow me to calculate ERP based on field strength at a good distance. This will allow me to check the accuracy of my ERP measurements much nearer to home.

27 Sep 2010

Sub-9kHz Amateur Radio group: 100+ members already

Since creating this new group on Saturday it already has over 100 members. Now we need to see some postings from people actually doing activity down there in the "Dreamer's Band".

See http://tech.groups.yahoo.com/group/sub9khz/

26 Sep 2010

A good evening on 500kHz

This evening I was well pleased with my simple 500kHz transverter and the vertical wire loop antenna in the garden producing around 2mW ERP. The map shows stations that reported me on WSPR including LA3EQ at 769km, which is the best DX so far on the loop. The loop doesn't seem to be that directional surprisingly.

137kHz QRP transverter (provisional schematic)

Attached is a first draft of the 137kHz QRP transverter schematic. The values are not all correct or optimised on the circuit. Also the RX preamp has still to be added, but this is what I'm proposing to do. The TX is working pretty well (best DX 148km) and produces around 5W from the PA which runs cool and 20uW ERP. An updated version will appear on my website later. It may even get put in a box soon!

500kHz ERP with the vertical loop antenna

Results on 500kHz WSPR with the vertical 80sq m area loop (made from 1mm diameter wire) are very good with signal reports from G3XIZ this evening of +4dB S/N. M0BMU has given me - 4dB S/N. This leads me to believe the ERP of the system is now somewhat higher than with the short Marconi vertical. Based on earlier calculations I think my ERP, in the best direction, must be about 2mW now, some 6dB more than it was.

25 Sep 2010

6th unique WSPR reporter on 137kHz

This autumn is beginning to look a bit like last year when I was taking my first tentative steps on 500kHz WSPR: each week would land me a few new reports from more distant stations. This autumn my challenge is 137kHz WSPR and so far I've been copied by 6 different stations: G6ALB, G3XIZ, G3XVL, G3WCD, G3YXM and, this evening, M0FMT. Best DX remains G3YXM at 148km. Not bad for a true QRP station with less than 5W from the PA and less than 20uW ERP with the transverter just a breadboard on the desk and the ATU sitting on the bedroom table.

Also today I copied G8IMR, Andy Talbot's QRP beacon from Southampton on 137.530kHz.

Sub-9kHz Amateur Radio (Yahoo group) formed

This new group is for anyone interested in amateur radio communications below 9kHz in the so-called "Dreamer's Band".  See http://tech.groups.yahoo.com/group/sub9khz/

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.

24 Sep 2010

Another source of LF/MF and HF interference

This was posted on the LF reflector: we'll have yet another source of LF/MF and HF interference in the years ahead as more people install such systems. Hugh's post got immediate replies from people who'd suffered bad interference from such systems. beware of photocell panels on neighbours' roofs!
"My neighbour informs me that she is intending to have photovoltaic panels installed on her roof, in a scheme where she gets free electricity (all subsidised by the government of course!)

My concern is the possibility of high levels of interference generated by the kW inverters needed to pump electricity back into the National Grid. I would guess that such invertors probably operate kHz and might be expected to interfere with LF and VLF reception. The wiring to all the panels on the roof might act as a
very good aerial!

It also occurs to me that any lack of RF immunity to my transmissions, in the new installation, might have dramatic consequences - I know from studying electrical engineering at college that connecting a generator to the grid with incorrect phase leads to a big bang!

Has anyone any experience of such installations? Perhaps someone has one nearby and could comment on any EMC effects.

Hugh M0WYE"

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...*

21 Sep 2010

148km on 137.5kHz WSPR!

WSPR reports on 137kHz 21.09.10
Just had a report from G3YXM who gave me -24dB S/N on 137.5kHz when I was running no more than 20uW ERP.  He is now my 5th WSPR report on the band and the best DX by far. This is so thrilling! The transverter is just sat on my desk and the PA isn't even warm.
G3YXM's screen showing my weak signal on 137.471 kHz

Possible progress on a worldwide MF allocation at WARC 2012

Info on the ARRL website suggests the USA authorities are supporting an amateur allocation at MF. See Secondary Amateur Radio Allocation at 461-469 and 471-478 kHz

 

20 Sep 2010

The loop works well on 500kHz TX

Unique reports on 500kHz WSPR this evening
My vertical loop of 1mm diameter wire seems to work very well on 500khz WSPR with some excellent reports this evening, indeed some of these reports are better than I ever received (I think) on the short Marconi vertical last winter. Certainly there will be some directionality, which is the downside of this antenna. Results on 500kHz are SO much easier than on 136kHz where the lower radiation resistance and electrical size make it so much less efficient.

Loop antenna on 500kHz

My vertical loop antenna (about 80sq m area) made with 1mm diameter wire (tuned with a capacitance decade box) performs quite well on 500kHz judging by reports. Yesterday I lowered the bottom wire to run along the ground, increasing the loop area from about 70 to 80sq m.  Reports from M0LMH (223km) and M0BMU (69km) are pretty good with my 1mW ERP signal at M0BMU up to -5dB S/N on WSPR, which is as good as I've ever had and he's not in the best direction for the loop. Also, PA3EGO was up to -2dB S/N on receive. Results on 500kHz are much easier to obtain than on 137kHz although this is explainable by the much lower ERP (probably 20dB less than on 500kHz).

19 Sep 2010

Increasing interest in 137kHz WSPR

WSPR LF activity lunchtime Sept 19th
In the last week there seems to have been an increase in 137kHz WSPR activity. The attached image shows the stations active on 137 and 500kHz this lunchtime.  G8IMR was the call being used by Andy G4JNT for his WSPR beacon before it died.

Why NOT to use QRO on 136kHz

Andy G4JNT was testing a 600W RF WSPR beacon on 137kHz today when he noticed burning from the plastic shed used to house the ATU. When he opened the door he saw the plastic shed and shelf melting and flames everywhere which he quickly extinguished.  LF at high power can be dangerous stuff and one reason why I've restricted my activity to QRP.

18 Sep 2010

New all-band SDR from Funk Amateur

SDR transceiver PCB assembly
http://www.dh1tw.de/first-pictures-of-allband-software-defined-radio-fa-sdr-trx

The German magazine Funk Amateur has a new all-band 1W SDR transceiver kit in the October edition. This will sell for around $170 US and looks a very interesting project. More details from the link above.

137.5kHz WSPR - best DX now 61km with less than 20uW ERP

137.5kHz WSPR reports so far today - with <20uW ERP!
Just got a -27dB S/N report on 137.5kHz WSPR from G3XVL near Ipswich at 61km. This is particularly good as this is more or less in the null of my TX loop antenna: in the better direction the signal could be some 6-10dB stronger!

From Michael Rainey's blog

http://aa1tj.blogspot.com/2010/09/verweile-doch-du-bist-so-schon.html

Michael Rainey AA1TJ has an excellent blog in which he covers a range of subjects. This post (see link) is about a tiny pocket watch made almost entirely from wood and other organic materials that Michael came across in a museum in Vienna.

WSPR success on 137.5kHz

G3XIZ's 137.5kHz WSPR reports today
Chris G3XIZ has successfully received my QRPp WSPR beacon this morning on 137.5kHz. ERP is around 10-20uW from the class-E PA producing around 4-5W. This brings my total number of WSPR reports on the band to two with the best DX now 46km.