Embedded Files
Dec 30th 2013
Some of you may have heard that I've (G3XBM) been in hospital in Cambridge since mid-September as a result of a stroke, so I have been unable to update these pages. My best advice is to check the LF groups on Yahoo and Blacksheep for latest VLF news. My apologies.
July 2013
Harry G3MFW reports on his earth-mode tests using a car mounted H-field loop RX antenna at 8.97kHz:
"I have completed my car Rx loop and it works very well for detecting VLF from my Tx which uses ground electrodes. It has 41 turns, tapped at 2 turns to feed preamp and laptop with Spectrum Lab. I put 2 metal roof bars on my Astra, and tied 2 pieces of 2x1 inch timber 12 feet long to the bars along the length of the car (no overhang). Using 8.5 metres of 41 wire telephone cable, I connected the ends together in series to form a 41 turn horizontal loop, and tied it to the wooden bars to form a loop with an area of 2.8 square metres. The 2 ends and tap were fed through the top of the passenger door window. The loop has a sharp resonance at 8.97 KHz with 0.0165 uF and a Q of 24. I know the car is a "shorted turn", but it has very little effect on tuning or Q. It makes underground signal strength mapping simple (but it works even better if you get out of the car and lay the loop on the ground! However, this is much easier than putting earth rods in tarmac)
73s Harry G3MFW"
July 26th 2013
News from Alaska of grabber changes at Lawrence KL7L
Please note that the domain name for KL7L (x KL1 X KL7UK) is now http://KL7L.com the other sites will die soon.
Snappers (grabbers) are (mostly) visible as
http://kl7l.com/Alaska.html - for a rolled up view of all 4 snappers below
http://kl7l.com/med00000.jpg for typically a medium speed signal strength view of some VLF stations updated a few times a day - used mostly to look at diurnal changes/flare
http://kl7l.com/fast00000.jpg for VLF wideband view
http://kl7l.com/slow00000.jpg for typically the 8KHz Dreamers section signals – paint drying – I can see a faint line on 8270 if I squint J
http://kl7l.com/Alaska00000.jpg typically HF QRSS/MF or LF Argo/Speclabs shots.
My main LF/MF array is down and most of the cables are rolled up as we are in the middle of a large house project and there are really too many smelly signs of bears to be tramping in the woods at the moment. Im installing large(r) 4 inch duct between the house and the antennae
I am or can use the VLF probe on MF and LF so I might bring that on line soon. My second dead Icom R75 has been brought back to life – dead electrolytic on the -5V rail – guess things are getting a little dried out as its the second R75 to go down this year.
The sun is setting before 11pm so Autumn isnt far around the corner up here...
73
Laurence KL7 L Wasilla Palmer Alaska BP51 Eye Pee
July 17/21st 2013
News from Germany of an upcoming VLF test at 8.970kHz using earth electrodes as the TX antenna with an ultra-stable Spectrum Lab derived signal.
Hello Group,
We are planning some VLF-activity at 8970Hz during a meeting of electronic hobbyists nearby Kassel / Germany (JO40vr) on this weekend. The plan is to run a VLF-PA between some ground electrodes. Due to other activities we have no exact time plan, when to start. Depending on internet access i will inform you about the details.
Thanks for looking for our signal in advance.
73s
Eike DL3IKE
UPDATE 21.7.13
Hi everyone,
I´m glad to inform you, that our VLF PA is since 20min running. We had some trouble with the Y-capacitors in the switching power supplies. They didn´t like the 8970Hz and burned up. We have now an alternative power supply with conventional transformers.
We are driving now ~100Watts into earth electrodes over a distance of ~250m. The DC-loop resistance is ~30 ohms.
TX frequency is 8970Hz.
We plan to increase the ouput power in the evening. I´ll inform you then.
Vy 73s de Eike DL3IKE
July 4th 2013
Henny PA3CPM has been continuing his 8.270kHz transmissions, on and off, for some weeks now and is getting reports from several stations in western Europe despite his modest antenna. On the left is a photo of Henny's huge loading coil used to bring his 40m sloper to resonance on 8.270kHz. The loading coil uses a LOT of wire (several kms) and building such a VLF loading coil is not for the faint hearted! Henny is using a 200W PA and this is shown on the right. Note the fans to cool the unit. Our thanks go to Henny for his VLF transmissions.June 17th 2013
Henny PA3CPM has been continuing his 8.270kHz test transmissions with very modest equipment and been spotted on several grabbers in recent days including DK7FC's. Henny is one of the few stations transmitting on VLF currently, apart from those testing with earth-mode.
May 7th 2013
Henny PA3CPM continues his 8.270kHz test transmissions but is having issues with his neighbours hearing the 8.270kHz tone emitted from his coil and feed wire! People continue to look for his signal, including Marcus DF6NM (see below):
"Henny,
thanks for leaving the power up this afternoon. I am quite aware of the acoustical noise problem, the situation is very much the same here. I have tried to cover the coil but the high voltage uplead to the antenna seems to be beeping as well.
This afternoon I ran the 0.477 mHz VLF grabber here in Nuernberg, unfortunately no trace here, maybe I started too late when the qrn was already coming up.
In addition, I made an experiment to extract 0.477 mHz spectrograms from Paul Nicholson's timestamped Ogg/Vorbis streams, fed by Paul in Todmorden and Wolf in Spenge (rawtcp://67.207.139.49:4416 in stereo). Their GPS-derived timing and samplerate are very accurate. Sharp spectral lines could be obtained from the Alpha stations on 11.905 kHz, so phase coherence miraculously seems to be preserved through the audio compression process. Then today I tried to pick up your carrier in both feeders but unfortunately no joy here either, yet.
However I have to say listening to the streams is well worth it anyway, you'll be rewarded by numerous tweeks and occasional whistlers tonight.
Best 73,
Markus (DF6NM)"
April 24th 2013
Recent days and weeks have seen activity continue on 8.270kHz with transmissions from DJ8WX and, in recent days from Henny PA3CPM. Both stations have been widely copied by Paul Nicholson and others. Henny's antenna is not that large at all: just a 14m long sloper, proving that results can be obtained with quite modest transmitting systems.
April 7th 2013
Quite a bit of activity in recent days! Marcus DF6NM and Uwe DJ8WX have both been testing around 8.270kHz and been received on the European grabbers. Marcus was running around 10uW ERP but was visible on both the OK2BVG and Paul Nicholson grabbers. Uwe is running more power. We are still hoping that DJ8WX will be copied in Alaska.
April 2nd 2013
News from Paul Nicholson:
Morning Roger und Uwe,
We have a genuine signal overnight, on 8270.02523 Hz at very roughly 0.4fT,
http://abelian.org/vlf/sg8270.php
The weak signal on 8270.041937 Hz is my testing of some GPS controlled DDS software on a Raspberry Pi computer.
Paul Nicholson
March 31st 2013
Paul Nicolson (Todmorden UK) reports he has set up a temporary 8.270kHz grabber to look for DJ8WX when he tries again to be copied in Alaska and elsewhere in the coming weeks:
Hi Roger,
I've put up a temporary spectrogram covering 8270Hz give or take 50mHz. The orientation is fixed in the general direction of DJ8WX.
http://abelian.org/vlf/sg8270.php
The display spans 3 days, is updated every 15 minutes, and lags by about an hour.
Paul Nicholson
March 25th 2013
There is a lot of excitement at the moment as an 8.9700kHz signal has appeared on the Alaska grabber! It may be a local artifact or possibly DJ8WX. More tests are taking place to confirm one way or the other.
In the coming days Uwe DJ8WX is altering his antenna and TX to transmit on 8.270kHz instead of 8.970kHz. A further transmission will take place to see if his signal appears in Alaska. Exciting times.
March 23rd 2013
Uwe, DJ8WX continues to put a good signal around Europe on 8.97kHz. See this email to the RSGB LF refelector today:
Hi Uwe,
Your 8970 Hz signal is widely visible across Europe
http://abelian.org/vlf/fbins.shtml#p=1364032800&b=070&s=sp
http://www.ok2bvg.cz/vlfgrabber/
http://www.iup.uni-heidelberg.de/schaefer_vlf/DK7FC_VLF_Grabber.html
http://dl.dropbox.com/u/23312120/vlfgrabber.html
and now also good traces here
http://www.mydarc.de/df6nm/vlf/vlfgrabber.htm
Best 73,
Markus (DF6NM)
March 18th 2013
More news of 8970Hz tests by Uwe DJ8WX:
"last days I made some tests on 8970Hz, mode CASTLE, shift 0,002Hz transmitting the letter “W” in 5000sec/dot. Pse see: http://abelian.org/vlf/fbins.shtml#p=1363442400&b=080&s=sp the signs could be seen on all grabbers I know. Now I changed the speed and the shift to 10000sec/dot and 0,001Hz, I`ll give the PA some coal extra."
Laurence KL1X WE2XPQ has improved his VLF receive capability with a new E-field probe. He is hoping to copy some European VLF amateurs soon.
March 11th 2013
News from southern Italy of an experiment by Riccardo IK7FMO using earth mode. He transmitted on 8.97kHz using 50W to 40m separated earth electrodes in Polignano a Mare (Bari) south east Italy and detected the signal with an E-field probe (1m long whip) on his car, much as G3XBM did earlier in the month. The pictures show the route taken and the signal levels received. Riccardo also noticed stronger signals when driving through villages. The best distance at which the signal was copied was 3.15km.
March 1st 2013
Today G3XBM carried out a mobile RX test on 8.977kHz. TXing a continuous carrier with the 5W earth-mode transmitter, the local signal was detected using a mag-mounted E-field probe on the car with a laptop running Spectran continuously monitoring on the 4km drive between two villages. More details at http://g3xbm-qrp.blogspot.co.uk/2013/03/mobile-on-897khz-vlf.html
Feb 27th 2013
Transatlantic amateur VLF reception soon?
Transatlantic amateur VLF reception soon?
In an interesting email from Paul Nicholson, he mentions the possibility of transalantic amateur VLF reception:
"Earlier this month DJ8WX made a long pure carrier transmission on 8970.022 Hz from near Hamburg and was a good signal in the UK. I made several 9 day integrations of the signal at Marlton (New Jersey 39.9N,74.9W) but was unable to detect even a trace of Uwe's signal.
I tried bandwidths from 1mHz down to 270uHz and made many runs, selectively averaging daytime or nighttime paths. Also tried a range of filter and sferic blanker settings. This kept Mike's VLF computer very busy for several days, running and re-running several days of raw recordings.
But nothing at all. Not even a hint of a peak forming which might suggest a few more days would bring it out of the noise. I'm a bit surprised and disappointed, as Uwe puts a very good signal into UK (range 800km) with a one hour integration in 270uHz. Range to Marlton is around 6250km, eight times further but you'd think that a 200 hour integration would make up for some of that. Makes me think something else is wrong but I'm not sure what. I really thought we might pick up a trace at least after adding up the signal for 9 days.
I believe Uwe is doing some experiments with GPS frequency locking so we might be able to to try a narrower bandwidth, although surely over such a path, the phase will be shifted around quite a bit.
We're still in the season when trans-Atlantic tests are viable, hopefully we'll get a few more shots.
--
Paul Nicholson"
Feb 25th 2013
Some excellent copy of DJ8WX today in the Czech Republic by Lubos, OK2BVG. See below.
Feb 22nd 2013
DJ8WX has been experimenting with a new GPS locked frequency source and is trying to put a signal out on 8.9700000kHz.
The signal has been received strongly by several stations including Paul Nicholson in Todmorden and at PA1SDB.
Hello Uwe, VLF
Befor yesterdasy was the freq. always 8970.0222 Hz
Yesterday I measure you at 8969.9944 Hz
Now (~15h) 8970.0003 Hz
Spectrum lab is stabilized by 22k1Hz (GQD) here.
73s Peter PA1SDB
The signal from DJ8WX in recent days as received by PA1SDB. Note change in frequency (was 8.970022kHz).
Feb 14th 2013
This is the excellent signal from DJ8WX as seen by PA1SDB in recent days.
Feb 6th 2013
Uwe DJ8WX had to turn his VLF TX off today for a period:
Hi dreamers,
the TX was off from abt 1230UTC until 1440UTC today because
1) my XYL was working in the greenhouses (metal framed) and
2) I took the advantage repairing the aerial (one of the anchorage ropes didn’t stand the sparks).
GL
Uwe/dj8wx/jo43sv
Feb 3rd 2013
Several European stations are reporting Uwe's signal. See for example Stefan DK7FC's report:
Hi Uwe,
Now your TX and my RX is veryyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyy stable and i got a very clear trace of you in 424 uHz in 500 km distance!
http://www.iup.uni-heidelberg.de/schaefer_vlf/DK7FC_VLF_Grabber.html
Congrats again!
73, Stefan/DK7FC
Jan 31st 2013
Uwe DJ8WX has been doing further tests today:
Hi all,
the TX is on the air agn.
GL
Uwe/dj8wx/jo43sv
Jan 28th 2013
DJ8WX is currently transmitting a continuous carrier on 8970.022Hz, so a good chance to check out your VLF RX systems.
Jan 25th 2013
News from from Richard IK7FMO in Italy:
I am running, from autumn 2012, experiments in earth mode with two poles in the ground. I have come to 4Km. away with amplifier 300 Wout. @ 8970,00. If you can become part of the table of the investigators of the dreamers band. I am preparing a loading coil for 8970to be coupled with a vertical of 30 meters. The intent is to come from my QTH in Polignano @ Conversano (Grabber distance +- 10 km).
Jan 24th 2013
Several amateurs in Europe have reported strong signals on 8970.022Hz VLF, a frequency used in the past by DJ8WX near Hamburg. It is some months since there has been any amateur "dreamers band" activity, so this is very welcome. This is the signal as seem in the Czech Republic on the OK2BVG grabber.
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