Nouveau record sur 8.97kHz

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F4DTL
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Nouveau record sur 8.97kHz

Message par F4DTL » 10 juin 2010, 10:31

Lundi 15 Mars 2010 , Stefan Schaefer DK7FC a réalisé un record du monde sur 8,97 kHz.
Stefan Schaefer DK7FC, a été reçu par Paul Nicholson au Royaume-Uni sur une distance de 830 kilomètres. Markus DF6NM 180 km a également reçu des signaux.
Stefan utilisait 250 watts dans une antenne verticale cerf-volant de 100 m.

Des informations complémentaires sur cette réussite remarquable peuvent être vues sur http://www.qrz.com/db/DK7FC

source: ref-union.org

F4DTL
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DK7FC's VLF PA

Message par F4DTL » 10 juin 2010, 10:33


F4DTL
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Re: Nouveau record sur 8.97kHz

Message par F4DTL » 10 juin 2010, 13:52

Thanks to all for trying to receive something!

Daniele, your picture shows the typical QRN situation in the summer. The minimum
is early in the morning and QRN comes up at arround 9 UTC +- 1h. That's why i
got up today at 4 UTC and started transmitting befor 7 UT. But even the minimum
QRN level seems to be much higher than in March, just as expected.
Never mind. It was a try and it cannot always be successful, otherwise it
wouldn't be something special ;-)

There was much to test on the TX side and all these tests were succuessful!

The new PA worked without any problems. I have attached a temperatur controlled
fan (stepless drive speed) and i never started to run although i starts at about
40°C. I assume, the TX power was at least 500W and my transmitted "C" took 40
minutes, so the PA seems to work quite fine.
I just have to add a remote control "shut down" switch by a fiber optic cable.
This is because as i was outside the car and the door was closed, the kite
turned in the wind and so the wire came near the car and there occurred a 3 cm
long arc into the car that stood about 20s! So it was no good idea to touch the
car or the PA that was placed on the car ;-) If i have a "shut down" switch via
fiber optic cable, it will be no problem, hi.

I really got 900 mA (800mA average) antenna current and a voltage of 28kV (rms)!
So, the ERP (average) was about 6dB more (abt 4mW) ! This should normally result
in more than twice the distance, so we will see what happens in some months ;-)
It must be due to the QRN that no one above 500 km received the signal cause the
angle of the kite was mostly very high. But the wind came from WNW and this
causes wind-QSB, so some DFCW-60 letters had QSD...

The new amperemeter is a fine and useful instrument in this setup! It makes it
much easier to resonate and to see how the antenna current changes due to the
kite movement. Some photos of the new PA and setup will appear on my site on
tuesday...

I checked those copper earth rods with great success. The current increased from
650 to 800 mA by applying one 1m rod and one 20 cm rod. While the generator
seems to run at its limit now, there is much potential to improve on the loss
site...

The first time i saw a ham signal on my grabber. Markus/DF6NM will follow i
assume :-)
The DFCW-600 signal was up to 25 dB above noise and was well visible even in
DFCW-60. I got the information that traces were vible in the DFCW-3 window in
the early morning but i have to check that tomorrow.

All in all i get better prepared for the next active period and am hopefully
that the 1000km can be reached within this year :-)

Thanks Markus/DF6NM for the informations during the operation and his activity.
Things will improve and improve :-)

73, Stefan/DK7FC

________________________________

Von: owner-rsgb_lf_group@blacksheep.org im Auftrag von Daniele Tincani
Gesendet: So 16.05.2010 18:05
An: rsgb_lf_group@blacksheep.org
Betreff: Re: VLF: DK7FC, DF6NM



I did an hopeless try just for fun :-) I have captured the attached screen
(time reference is CET). The signal around 8969.5 is too strong, so probably
it is local, even thought a 0.5Hz frequency error could be explained by the
loss of calibration of the audio controller in my PC.
Cheers
D.

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