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 |
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/
Labels:
dk7fc,
dreamers band,
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.
Labels:
g0kya,
propagation
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/ .
Labels:
qth locator
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 |
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.
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.
Labels:
8.76khz,
dreamers band,
earth electrodes,
vlf
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!
Labels:
8.76khz,
earth electrodes,
earth mode,
vlf
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.
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.
Labels:
dreamers band,
g3xiz,
grabber,
vlf
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 .
The resulting screen grab every few minutes appears at https://dl.dropbox.com/u/
Labels:
dreamers band,
grabber,
vlf
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,
Labels:
500kHz
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!
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.
Labels:
grandson
7 Nov 2010
Looking for G3XIZ on 8.9719kHz VLF
Looking for G3XIZ on 8.9719kHz - maybe a faint trace?? |
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 |
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.
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
Labels:
aa1tj
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 |
8.76kHz TX |
Labels:
8.76khz,
dreamers band,
earth mode,
vlf
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.
Labels:
500kHz,
marine data,
nato
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.
Labels:
dreamers band,
vlf
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.
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.
Labels:
8.75khz,
dreamers band,
nov,
vlf
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.
Labels:
nasa,
solar storm
26 Oct 2010
More DX reports on 500kHz
Log from early evening Oct 26th 2010 (500kHz QRPp WSPR) |
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.
Labels:
8.97khz
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.
Labels:
136khz,
500kHz,
earth electrodes
25 Oct 2010
Amateur VLF update: reception in 8 countries + 1310km DX!
DK7FC's summary of reports on Oct 23rd 2010 |
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 IK1QFK in Italy.
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.
Subscribe to:
Posts (Atom)