Essais TX VLF DK7FC

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F4DTL
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Essais TX VLF DK7FC

Message par F4DTL » 05 août 2010, 10:36

Dear LF/VLF group,

It took a long time to get a proper wind forecast in a time sector where i can do a kite experiment. Also it took a long time to get the special permission for the new kite antenna.

But now, if the wind will be enough and if there is no rain on Sunday, the 1. August, i will make a new kite experiment.

The first time i will try to use a 200m vertical antenna and 600W TX power. The L of the loading coil will not be reduced in this experiment and so i will transmit at arround 6,5 kHz, the 46 km or 47 km band! This is since i do not yet know the actual antenna C (EZNEC says 972 pF). The ERP will be arround 16 mW (first estimation). This is about 10 dB more than in the first and successful 2nd experiment on March, 15th. Also it is said that propagation on 6 kHz is even better than on 9 kHz! The first time it could be realistic to reach the 1A antenna current mark!

Since some weeks i have set up a grabber in DFCW-120 mode (just to cover a broader frequency range) at http://www.iup.uni-heidelberg.de/schaef ... bber2.html If you want to catch my signal, you can look there where i am actually transmitting. After some resonating tests i will transmit in good old DFCW-600, so it is the best you use a 3...5 mHz FFT and about 1 minute per pixel.

Starting time is 8 UTC, maybe some time later since it is the first experiment with such an antenna! I still do not know if big problems will occur but i am a DREAMER (remembering the 3rd experiment: http://abelian.org/vlf/ss100321/ ). But don't be disappointed if it would be failed. Actually it cannot fail since there will be found improvements for the next test!
TX QTH is as usual in JN49IS, 49.77647N 8.699525.

The summer time and maybe day time may be not the best but it is an important test for the winther period. Maybe we will see some surprises depending propagation on arround 6 kHz. And it will be the first time that an amateur reaches the far field and hopefully more than 1 Lambda on such a low frequency :-)

Any RX reports and ideas/hints (before and after the test) are very appreciated!

Best 73, Stefan/DK7FC *excited*

F4DTL
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Re: Essais 6,5 kHz DK7FC

Message par F4DTL » 05 août 2010, 10:37

VLF,

On http://abelian.org/vlf/ss100801/ you can find Paul Nicholsons most interesting final report on his reception and filter processing of this 6470 Hz experiment.

73, Stefan/DK7FC

F4DTL
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Re: Essais 6,5 kHz DK7FC

Message par F4DTL » 05 août 2010, 13:38

La reception de Michel F5WK avec sa boucle monospire de 1m de diametre, boucle deportée avec liaison UHF 400 MHz entre l'antenne et le recepteur.

Image

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Re: Essais 6,5 kHz DK7FC

Message par F4DTL » 24 septembre 2010, 00:23

Dear LF/VLF,

Today i saw the first time a flag from Norway on my VLF Grabber (http://www.iup.uni-heidelberg.de/schaef ... abber.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...*

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Re: Essais 6,5 kHz DK7FC

Message par F4DTL » 01 octobre 2010, 00:19

Dear VLF,

The wind forecast for saturday 2 october morning/afternoon changed to positive
values. Thus i just sent a mail to the german air traffic control and
announced a kite experiment and asked to give out a NOTAM. But actually
i have to do this 48 h before the activity. But it would be in 33 h so i
am not sure if they accept that. I asked for an answer and will call
them tmw so it is not sure if i can start. But if, the next activity
will be on saturday! Planned is 8970/6470 Hz. A 100m vertical is
possible without a NOTAM but i want the maximum ERP! ;-)
Will keep you informed...

73, Stefan/DK7FC

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Re: Essais 6,5 kHz DK7FC

Message par F4DTL » 02 octobre 2010, 01:03

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/schaef ... abber.html
The 6470 Hz will be visible at http://www.iup.uni-heidelberg.de/schaef ... bber2.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

F4DTL
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Re: Essais 6,5 kHz DK7FC

Message par F4DTL » 02 octobre 2010, 15:53

Update at 13:30: Generator still down, but Stefan is physically working hard trying to get the motor running again. The long dash 11:25 to 12:54 was sent using the small 12 V PA and car engine running. The noticable chirp (~ 18 mHz down) was attributed to sagging supply voltage for the DDS crystal.

Best 73,
MArkus

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Re: Essais 6,5 kHz DK7FC

Message par F4DTL » 02 octobre 2010, 15:57

Reception certe pas fameuse mais reception de F4DTL.
Malheureusement je suis arrivé trop tard sur la frequence,puis Stefan a stoppé son emission par manque d'essence dans son groupe electrogene.

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Re: Essais 6,5 kHz DK7FC

Message par F4DTL » 02 octobre 2010, 16:03

Reception de Jean Pierre F1AFJ avec plus de 650 km.

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Re: Essais 6,5 kHz DK7FC

Message par F4DTL » 02 octobre 2010, 16:08

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