Hello Michel,
Thank you very much for the interest and the appempt to catch the
signal. It's the first time i read something from you (regarding the VLF
tests) and i am generally impressed by the amount of people in so many
different countries who are present here on this reflector. The
reflector gives the feeling as something private and/or collective, not
so in an official web platform (personal interpretation).
Thanks for describing your RX setup, interesting!
Well, about your picture: If the time is in UTC, it matches the time of
my transmission very well! Sadly i have not transmitted a real
character, such as "K" or "C" or so. But your trace is stable in
frequency! This is not the case for the most signals on VLF!
Additionally, the trace shows the typical frequency offset of my DDS
VFO, about 30...40 mHz lower than in the display! This are all
indications for my signal! So i would say yes, it is a positive reception.
Maybe some others can comment if it can be seen as a valid reception. I
would say yes.
You can imagine how the reception would have been some hours earlier,
when the QRN was 10 dB less! :-)
Michel, what is our distance? My locator is JN49IS.
Best 73 and i hope you will be there in the next test as well :-)
Stefan/DK7FC
Am 02.08.2010 15:13, schrieb Michel F5WK:
Dear Stefan,
A big thank you for all the fascinating experiments you are leading.
I have been trying to receive your sigs from the very early stage but was'nt
succesful so far. However, this time, i got some faint traces I'm not able to
identify. Could it possibly be your signal ?
This time, I put a 1 meter one turn loop in the fields with a 433 MHz FM
feed to get rid of much of the local noise. The high gain preamp is using a
LC 7th order low pass filter to improve the dynamic range of the system.
73,
Michel - F5WK in JN18HP
Le lundi 2 août 2010 à 13:01:32, vous écriviez :
Dear LF/VLF group,
Many thanks to all the people who tried to catch may signal in the
yesterdays test! Thanks for taking the time to watch the QRG on a sunny
sunday! The RX side is an important factor in such a experiment because it
motivates the TX side when there is no QSO but just a reception. It makes
me glad that there is such an interest in those tests.
Special thanks to Paul Nicholson who did the effort to re-arrange his
antenna and software and the website with a nice overview.
Also special thanks to Markus/DF6NM for the telephone support about the
activity on the reflector, the lightning situation and the QRN situation.
This is an important feedback as well and much more interesting than just
having a mobile internet stick.
Congratulations to all the successful receiving stations! It was a test
in the middle of the summer time with heavy QRN. The QRN was on its daily
maximum as i was able to transmit at a high kite angle. The QRN was even
high compared to the last days during that time (still comparable in my
DFCW-6000/8,97 window on the grabber1). So, there is MUCH potential to get
a much better S/N in the winther period and at better wind situations.
Thus, i am very hopefully that e.g. Jim and Paul will catch that signal!
This makes the following experiment an optimistic challenge! I am even
sure that it will be possible to go down in the DFCW-mode, maybe to
DFCW-60. This makes it possible to try a cross band QSO (!) like
137kHz/6,47 kHz (or 8,97 first). Here i could use a small portable active
antenna for 137 that will not be too much swayed be the TX antenna...
As far as i can see there was a positive reception at least by the following
stations:
DF8ZR (QRSS-60 mode, 16km)
DK7FC (grabber in DFCW-240 mode, 40km)
DD7PC (congrats, first time! 53km)
DF6NM (insecure, fragments, 180km)
DL4YHF(impressive S/N!, 264km) Best DX reception of the lowest signal,
transmitted by an amateur so far (far field)
Paul Nicholson told me that he has recorded the siganl and will try to
work the trace out. Let's be excited about his proffessional and nice to read
report!
Now, i want to give a detailed report of the things that happened on the TX
side:
I arrived at about 9:40 UTC. It was no problem to arrange the equipment
and nothing was forgotten. Just before, the rain stopped but the wind was a
little to weak.
I used the 8,1m^2 kite but it took some hours until the wind was enough,
sadly. First, the wind increased just for some minutes. In that time i saw
that the wire was to long and was sagging to much.
After cutting some meters i could start the generator and PA and turned
the VFO wheel down until i saw a peak on the amperemeter. It was on 5,7
kHz but it was due to a very low kite angle. Later, as the wind increased
i could do more useful resonating tests. I found that i can resonate
between about 6,4 kHz to 6,6 kHz. Maybe this is due to the fact that the
wire has to be slighty longer than 200m since the kite braid is elastic
and will be 20m (10%) longer at strong wind.
After watching the 6,5 kHz sector in the last weeks i found that it is
best to transmit not on n*50 Hz or n*16,6667 Hz (frequency of the german
trains grid). Thus i decided to go about into the center, to 6470,00 Hz, within
the 46 km band!
First it was not possible to transmit a real "message" since the wind was
OFF sometimes :-(. My plan was to transmit "CU" in DFCW-600.
Than, an accident happened: Suddenly the was was off and i wasn't fast
enough to bring the kite down on the road. So the 200 € kite dropped in a
15m high tree! I felt like a child that lost his parents on the airport! I
was not strong enough to pull it out there with its braid. I saw no other
way to try it with the car, even when the kite gets damaged with this
attempt. So i fastened the braid on the car and drove some 10m until there
was a heavy pull on it. The braid stopped in a beginning corner of a corn
field and as i lifted it above the corn it sounded like a lash/whip. But
suddenly the kite came out of the tree and before it dropped on the bottom
it was caught by the wind and rised into the sky, hanging on my car I
drove back the the TX coil with the kite on the car...
After taking too much sun and after this stress i was powerless and not
motivated to improve the earth losses and so on but it was my absolute
goal to produce some nice signals for the RX stations, at least a limple
carrier! So i set up the whole arrangement and now the wind was stable,
lifting the kite continously above 45 deg, sometimes 70 deg. In proper
wind conditions, it is lifted to 70...80 deg.
The antenna current was about 750mA and after connecting the copper rod i
hammered into the soil in the 5th experiment it rised to 800mA. Then i
reduced the primary winding number from 70 to 60. Then, the current was up
to 920 mA, the highest current so far. Just before 16 UTC the fuel of the
generator was empty and my fuel as well That was the end of the 6th
experiment.
So, my overall losses are about 600 Ohm now. The ERP was about 11mW and
the voltage just about 20 kV rms. I am sure to be able to decrease the
earth losses to 200 Ohm and the coil losses will be reduced to 200 Ohm as
well since i can reduce the L to come back to 8,97 kHz.
Now i know the C of the wire and can make a reasonable tap on the coil,
at arround 275 mH! So, in the 7th experiment i can transmit on 6,47 kHz as
well as on 8,97 kHz. I just have to change the coil connection and the VFO
frequency and that can be done in< 2 minutes.
I will spend some experiments on this 200m antenna now before going to
300m. And i want to test it on 137 kHz With a 300m antenna, i will
explore the 58km band in future tests! Also, just for fun, i want to
transmit on 7355 Hz. This frequency is a message in it selfe for amateurs
So, all in all it was a hard experiment with many difficulties and the
QRN situation could have been at least 15 dB better but it was an
important test to find the tap for the L to come back on the Dreamers Band
(33km) with a 200m vertical. Also we have done some new record receptions
and can be very hopefully that this can be much improved in the next test,
if there is proper wind and less QRN that can be assumed when going to the
autumn
Again thanks to all the group and hope cuagn in the next test!
Best 73, Stefan/DK7FC
PS: Some photos and screenshots will be displayed on my QRZ.com page in some
days.
PPS: Hopefully there will come up further stations on the dreamers band within
this year
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