DK7FC's 10th VLF kite experiment

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F4DTL
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DK7FC's 10th VLF kite experiment

Message par F4DTL » 04 février 2011, 18:12

Dear LF/VLF group and other interested listeners/watchers,

After a break of 2 months i will do my next VLF kite experiment on sunday, 6th februrary 2011. I've got the permission to fly a 300m kite vertical antena in daylight. My plan is to start early in the morning, coming on air at about 7 UTC.

The wind forecast tells that the wind will be above 18 km/h (3 bft) but will decrease in the afternoon. This is a job for my smaller kite (3.6 m^2). Maybe i have to change to 8.1m^2 in the afternoon.

Such a kite experiment is always very exciting and a little chaotic too. So i cannot tell a too detailed and strict TX plan. The antenna consits out of 2 pieces, a 200m and a 100m part. The 200m part is the first that is lifted. Usually i want to serve 3 VLF bands: 33km, 46km and 58km. The antenna is only resonatable at 46km / 6470 Hz if the 200m piece is connected. Thus i started on 46km in the last experiment. But due to the necessity to become QRV on 33km / 8970 Hz as early as possible to make a TA contact i want to start on 8970 Hz on sunday, maybe transmitting at 200m while rolling out the second 100m part. Anyway, if possible it's better to watch on all the 3 bands simultaneously, like 4X1RF, TF3HZ, KL7UK, DK7FC and others do it :-) But usually you'll be informed here by the group what currently goes on. My VLF grabber in 40.0 km distance will display the activity. 8970 Hz can be viewed at http://www.iup.uni-heidelberg.de/schaef ... abber.html and 6470/5170 Hz at http://www.iup.uni-heidelberg.de/schaef ... bber2.html

If the wind, interest and my personal energy holds on i will be transmitting from 7...16:30 UTC. TX power will be 550 W. Depending on the soil humidity this will result in up to 100 mW ERP on 8970 Hz. As usual, my TX location ist JN49IS36VH

If all works well i'll try to reach the following goals:
-Transmitting a constant carrier for about 1 hour (GPS locked) at 8970.00000 Hz at full power (it's always full power! ;-) ), hoping to leave a strong trace at several curious VLF receivers :-)
-Transmitting a message in DFCW-600 at 8970 Hz to give a better ID and to keep the activity interesting
-Trying a DFCW-3 crossband QSO with DF6NM on 9/137 kHz at 179 km (http://no.nonsense.ee/qthmap/?qth=JN59N ... JN49IS36VH)
-Transmitting a short message in DFCW-10 for well equipped stations in a range of some 100km. Just to check how far DFCW-10 can be detected
-Maybe trying a CW QSO with DF8ZR in 16km distance (who strongly improved his station)
-QSY to 5170 Hz / 58km or maybe 6470 Hz, depending on the feedback and the diurnal noise situation
-Transmitting a carrier and some shifted DFCW-600 letters to give better ID.
-Spontaneous tests depending on request, wind situation, QRN and personal energy

-Reaching the TF3HZ VLF grabber in DFCW-600 (http://simnet.is/halldorgudmunds/TF3HZ_VLFgrabber/ ). Halldor has put a lot of energy in this project, mni TNX!
-Reaching other grabbers like 4X1RF and maybe KL7UK (the limit of my optimism!: http://no.nonsense.ee/qthmap/?qth=JN49I ... rom=BP51IP ) or even a university in India(?). Generally reaching as many stations as possible. EI8JK, many stations in UK (G3XBM, M0BMU, or even GM4SLV?), some new of them (G3XDV, G3KEV?), maybe a first contact in Russia,RA3YO? And norway, LA3EQ? I've heard from the yahoo VLF group about stations in Romania/YO.
-Hoping to give VLF interested OMs a chance to check, compare and improve different antenna systems.
-Maybe convincing a station in Greenland/OX to put some interest on the bands below 1 MHz? :-)
-Making a fascinating day for all involved.
-Improving the station by reducing the ground losses of the system. Reaching 1.4 A / 15 kV rms at 8970 Hz

As far as i can see there is no chance for a DX distance record as long as i don't reach so far unknown stations or stations in USA/Canada or India. But the main aspect is not the distance record, although interesting and fascinating and exciting, but rather having fun, active "Dreaming" and making some interesting observations :-)

So, hope for a good activity and good wind conds. Any reports are highly appreciated. RX stations are THE important part of such an activity! Thanks in advance!

73, Stefan/DK7FC

PS: Some grabber links:
http://qsl.net/4x1rf/vlf/vlfgrabber.htm
http://www.mydarc.de/df6nm/vlf/vlfgrabber.htm
http://www.iup.uni-heidelberg.de/schaef ... abber.html (8970 Hz in 40 km distance)
http://www.iup.uni-heidelberg.de/schaef ... bber2.html (6470 and 5170 Hz in 40 km distance)
http://simnet.is/halldorgudmunds/
http://kl7uk.com/VLFAlaska.html
There are many others available. The above are running 24/7. Sorry if there was someting forgotten.

F4DTL
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Re: DK7FC's 10th VLF kite experiment

Message par F4DTL » 06 février 2011, 01:41

Hello Marco,

Good idea :-) Surely i will receive you on 137 kHz, now with my small /p receiver (still not optimised but already working). Well, let me do the QSO with DF6NM and try to receive my signal in DFCW-3. Would be good to prepare a suitable USR file and add it to the quick settings or so. Or run a separate SL instance. If you can see me in 3, we could do a 9/137 QSO. If not, try to receive in DFCW-10. If this works, we might do a short QSO in 10, like you suggest. But 10 is the limit (as Mal always says) for a QSO. Look back to your old captures: If you can see my DFCW-600 signal at > 30 dB SNR, we could have a chance in 3.

I think F4DTL or F5WK or OE3GHB or SQ4BPF will have a chance to see me in DFCW-10, depending on the QRN situation...

Marco, will you be at home to make some QSP to the reflector if Markus/DF6NM will have no time? I still have no confirmation that he will have the time.

73, Stefan/DK7FC

F4DTL
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Re: DK7FC's 10th VLF kite experiment

Message par F4DTL » 06 février 2011, 16:07

Très belle réception de DK7FC/P sur 5170 Hz cet après-midi.
Conditions VLF habituelles pour moi en portable à Soignolles avec boucle monospire 1m de diametre, transfo de courant et preampli faible bruit OP27. RX Spectrum Lab config DFCW600.
Le temps de réception est déterminé par la durée de vie de la batterie de mon PC portable.

73 de F4DTL Nicolas

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Re: DK7FC's 10th VLF kite experiment

Message par F4DTL » 08 février 2011, 19:25

Dear Nicolas and Jim,

Many congratulations to have successfully received this 58 km band
transmission for the first time! It was a pleasure to get some more
feedbacks on that Very Low Frequency :-)

For some of the next experiments it is planned that Markus/DF6NM wants
to vistit me. He will carry his VLF coil to the hill too and we will
couple them. Then, we will come down to probably below 3 kHz. We want to
do some tests on 4 and 3 kHz, hyper-dreaming ;-) But this will be
announced before. Maybe you want to try even that? We always want to
keep some challenges available :-)

Best 73 and hope you'll be on the RX site again in the next experiment.

Except from the looong transmissions i want to spend some time to do
some QSOs in DFCW3 or 10, since this worked much better than ever
expected. Jim, if you can, please try to do this before Mal does it
since he would write at least 10 mails that he is the best operator and
RX station ever! ;-)

73, Stefan/DK7FC

F4DTL
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Re: DK7FC's 10th VLF kite experiment

Message par F4DTL » 09 février 2011, 16:12

Dear LF/VLF group and further VLF watchers :-)

After another very successful, exciting and fascinating /p VLF experiment i want, as usual, thank all the many (>=24) receiving stations who took the time to arrange a suitable antenna/receiver, PC and to watch the experiment and take some interesting captures. The transmissions took place on 2 VLF bands, 33km (8970 Hz) and 58km (5170 Hz).
So, thanks to TF3HZ, SQ5BPF, G4WGT, G3KEV, Daniele Tincani, G3WCD, G3XDV,M0BMU, G3XBM, OK2BVG, OE3GHB, G4AYT, IK1QFK, DL3ZID, F4DTL, OE5ODL, PA3CPM, PA3FNY, DL4YHF, DF6NM, DJ2LF, DD7PC (bold = 1st positive reception on VLF).

Special thanks to Halldor/TF3HZ who wasn't member of this group before but set up a very sensitive VLF receiver and even a most intersting grabber just by my email request. This is the first VLF detection between DL and TF. My signal appeared at up to 15 dB SNR in 4.5 mHz in 2404 km. This helps a bit to get some imagination how far a transatlantic detection is away.

Sorry to those who tried without success this time, like 4X1RF. The next experiment will come soon, maybe in about one month.

Now, as usual, a looong report about last sunday:

The alarm clock ringed at 5:30 local time (4:30 UTC). The equipment was already put into the car before. I arrived in the dark on the hill at 5:45 UTC and had to use my head lamp to build up the TX system. I am getting more and more relaxed and routined in building up the system. The wind was strong with some even stronger flurrys (like announced in the forecast) so i decited to use the 3.6 m^2 kite. It was a relatively warm day (compared to the 9th exp) at about 5 to 7 °C.
After rising the kite to 200m i started to transmit on 8970 Hz while rolling out the second 100m long part since i didn't want to miss any minute in the early morning. A capture of my total 8970 Hz activity can be seen at http://www.iup.uni-heidelberg.de/schaef ... 0thEXP.jpg

Unfortunately my soundcard wasn't accurately locked to GPS within SpecLab as it seems. Thus the signal looks fuzzy. Anyway there was good copy on most receiving stations. Maybe this is caused by a high local E field strength influencing the antenna but actually there was no difference to the setup of the 9th experiment. I will work this out!

So the transmission started at 6:50 UTC. After getting the full 300m the signal became 15 dB stronger on my grabber ( i didn't get exact resonance with the 200m part). Since it was wet i got an average antenna current of 1 A and peaks of 1.2 A at 8970 Hz, resulting in up to 84 mW ERP and 13 kV rms on the wire.
The day before i bought a sledge hammer and hammered 2 long massive steel earth rods into the soil. Since the soil was wet below the copper plate and due to the rods it was possible to reduce the earth losses to about 65 Ohms!! So the antenna efficiency was up to 0.013 % which is very high :-) But unfortunately the generator seems to become weaker and weaker. The average applied power was just about 250W. Actually it should be about 600W :-( So, another part to improve or to replace. Thinking positive, this means i can improve my signal by at least 3 dB if i get the generator running or 9 dB if i choose a 2 kW type.

After transmitting a constant carrier at 8970 Hz for 80 minutes i transmitted DFCW-600, for better ID at the various receivers. The message was "FB-fine business", just for fun... After that i did the first LF/VLF xband QSO in DFCW-3 with Markus/DF6NM over a distance of 179 km! There was no problem to copy our signals in the first attempt :-) This was very pleasing. Captures of this QSO can be seen here: http://dl.dropbox.com/u/19882028/DFCW3_ ... 137kHz.rar Although solid copy of DF6NM was possible, the SNR was much lower than expected. It is at least 15 dB lower than during driving on the highway near HV transmission lines, even when the generator and so the netbooks power supply is off! There was no improvement/change when the 300m wire was disconnected or grounded. So i have to work on this too...
To my surprise i got informations (by mobile phone) that some other stations seem to see me in DFCW-3 (like OK2BVG). So i will plan much more QSOs in the next experiment.
Since the generator would have problems to stabilize the driving speed when doing a DFCW-3 or CW transmission, i added such a tiny capacitor of 60000 uF / 350V which averaged the load pretty good! This even means that the TX power in CW or 3 is even higher than in DFCW-600!! When switching on the PA after recharging the capacitors i got up to 1.7 A for a short while :-) A definite goal in this year is to get 2 A antenna current. This may be the limit of this coil regarding power dissipation and voltage stress (abt 30 kV rms).
After the QSO to DF6NM i did some CW transmissions. I did a recording of the audio stream in a 30 GB wav file that is analysed in the moment. Maybe this CW signal is audible in 40.0 km distance. I will report on this later. It was funny to have a CW sidetone on 700 Hz and on 8970 Hz together :-)
During the CW transmission the photographer of the last experiment visited me again, taking a friend (also a photographer) there too. There have been about 15...20 visitors on the hill asking interested what i am doing :-) They both wrote a short article with some photos, see http://mkorbit.de/2011/02/08/signaluber ... welle-vlf/ and http://peweb.de/2011/02/06/dk7fc-signal ... welle-vlf/
After the CW message i moved to 5170 Hz, transmitting a long carrier while talking to visitors there. Later i added a "K" in DFCW-600 just for ID. During that time there was no QSP to the reflector except some SMS to SQ5BPF and 4X1RF (thanks for the entertainment). BTW thanks to DF6NM for QSP to the reflector during the first hours. I will now actually try to improve my /m antenna for the 30m band to give better chances for skeds.
Due to the low feedback i thought there is not much interest in 5170 Hz although i like that band very much. The coil is still not resonated but anyway i reached the limit of the generator, resulting in about 800 mA antenna current, so up to 12 mW ERP on the 58 km band. BTW Markus/DF6NM is planning to visit me in one of the next experiments carrying his coil there. We will couple them and try to transmit on 4 and 3 kHz! I estimate we can reach about 6 mW ERP at 3 kHz :-).

Another story: Jacek/SQ5BPF asked me via SMS to make QSY by 10 Hz for 1 minute. So i switched to 5180 Hz for a while. After that i pressed the DEL button in the text field of SpecLab where the TX frequency is typed. I did this during transmitting. I wanted to replace the 8 by a 7 to come back to 5170 Hz. Suddenly i heared a short BEEP! at a much lower frequency and realized quickly that i obviously transmitted on 510 Hz :-) But all this is no problem for the PA :-)

Later i came back to 8970 Hz. No transmission on 6470 since i have to reduce the antenna to 200m for this and wasn't sure if a QSO to HE3OM on 137 was possible... In the late afternoon the WX was fine, sunny, warm but the wind slightly decreased and the antenna began to sag. Since i didn't want to go home and loose this valuable TX time i actually changed the kite and used the 8.1m^2 kite later. This one is much more stable in the wind and at a high angle! So my average ERP must have been a bit higher in the late afternoon. This gave Roger/G3XBM the chance to copy me later. I haven't known all that on the hill ;-)
Some DFCW-10 messages and DFCW-60 (http://dl.dropbox.com/u/19882028/dk7fc_ ... 6_1652.jpg) was the last transmission of my 10th VLF experiment.

Ending arround 17 UTC and slowly building up the setup needs to use the head lamp again! It takes more than a hour to build up and down the system. So i spend the whole day on the hill and had a lot of fun there.

I'm once again happy about so many detections by stations across EU/UK/Iceland and hope you'll be there in the next experiment, would be pleased about that :-)

A list of successful receptions of my 10th experiment with locator and distance can be found here: http://www.iup.uni-heidelberg.de/schaef ... C_10th.png
A complete list of positive receptions of all my experiments can be found here: http://www.iup.uni-heidelberg.de/schaef ... FC_all.png
A google earth map of these stations can be found here: http://www.iup.uni-heidelberg.de/schaef ... _200km.png
A google earth map of rather local stations can be found here: http://www.iup.uni-heidelberg.de/schaef ... _local.png
Last not least a map that shows the presence of the sun during my attempt to leave a trace at Laurence's / KL7UK VLF grabber in the early morning: http://www.iup.uni-heidelberg.de/schaef ... ng_sun.png

So, see you in the 11th experiment. :-)

Vy 73, Stefan/DK7FC

F4DTL
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Re: DK7FC's 10th VLF kite experiment

Message par F4DTL » 09 février 2011, 16:13

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