Hello Stefan, LF!
Thanks for your information about nice VLF weekeend, they are
interesting for me and my friends SWL as well. I continue in tests
of my VLF loop antenna - if it works well, I will send you some
info.
73!
Lubos, OK2BVG, JN88KS
*********************************
Dne 7.12.2010 18:54, Stefan Schäfer napsal(a):
Dear VLF/LF group,
After a very exciting and stressing VLF experiment i am back in
the
civilisation and am relaxed again. It was a very hard fight with
kite
in the dark cold until i have pulled it down after one hour!
A new distance record by amateurs on VLF was reached, 2873
km
distance
in DFCW-600 with a good SNR by 4X1RF on 8970 Hz and even
fragments
on 6470 Hz.
Chris recorded the signal as a wav file so we can re-process the
experiment in a even smaller FFT to at least extract a dash with
better
SNR. Congratulations!!! :-)
Many thanks to all the many receiving stations all over the world!
That
makes me glad to see the effort, people are doing to receive my
weak
signal (e.g. F4DTL). The receiving stations are an important part
of
this
experiment! Not only new stations and/or distance records are
fascinating but each station, no matter what the distance is!
There
have been 23 stations in 9 countries and 2 continents who
successfully
managed to receive the signals, partly on all the 3 VLF bands
where i
can transmit.
Special congratulations to 4X1RF, G4WGT, G3XBM, OK2BVG, G4AYT,
F4DTL
and ON7YD for the first successful reception on VLF. OK2BVG is the
first contact between Germany and Czech Republic, ON7YD is the
first
contact between Germany and Belgium, 4X1RF the first contact
between
Germany and Israel (that counts to Asia if i am correctly
informed).
Attached you find a list of the successful receptions just of this
9th
experiment. The overall receptions of my kite experiments and a
geographic card will appear on my QRZ.com page in a few days.
Lets hope the activity, not only mine, can be increased even more
by
the upcoming stations with fixed antennas! It is worth to try it,
even
if much slower modes are necessary.
Now my report about the 9th experiment:
The wind forecast said that the wind will start to come up arround
9
UTC and that was true! So i arrived about 8 UTC on the hill. The
temperature was about -6 °C and this didn't change during the day.
But
the sun came out and it was, once again, a wonderful day in the
field.
I have had 2.5 liters hot tea and enough to drink and fuel for the
generator to stand a 10 hours activity out there. The wind was at
excellent strength and stable. Once i lifted the kite it was up in
the
sky until i pulled it down! No QSB ;-)
After lifting up the first 200m i got the idea to start at 6470 Hz
since i cannot resonate a 300m wire on this frequency, just 200m.
Unfortunately some RX stations missed my 6470 Hz due to that
change in
schedule. (Hint: You can run all the 3 SpecLab instance to the
same
time, just by 3x double clicking the SpecLab symbol and load
each
of the 3
usr files into one instance! This takes some more CPU power but it
is
no problem. So you cannot miss anything. Its like having 3 TVs for
each
of the 3 programs ;-). )
Since the whole hill was covered by dry white snow, i haven't
found my
buried copper rod into the earth and so i had just the copper
plate and
one /p earth rod. But the sun shined on the copper plate and
seemed to
melt some of the snow under the plate, so the contact was not to
bad.
On 6470 Hz i managed to get an average antenna current of
800 mA , equal to up to 9 mW ERP and 18 kV rms on
the
antenna wire.
After that, the transmission on 8970 Hz followed. I have had
several
mobile phone contacts to DF9PW and top DF6NM but suddenly i got
the
message of the positive reception in Israel and a call from 4X1RF.
This
was very pleasing and exciting :-)
To my surprise my signal was visible in QRSS-3 at DF6NM but
unfortunately i haven't had a suitable RX on 137 kHz available to
this
time. In the next experiment i will be better prepared on
receiving LF
(and HF,
for some crossband contacts) and will try to make the first xband
QSO
on 9/137 kHz DFCW-3/CW to DF6NM.
After preparing the loading coil and making a tap at 190 mH
(RDC=180
Ohm, which is rather worse) i easily found the resonance at 8970
Hz on
the 300m vertical antenna which was very stable at a high
angle
(> 60 deg) for the whole transmission! Here the achieved antenna
current
was up to 1 A (950 mA average) so i reached an ERP of
58 mW
and the voltage was just 10 kV rms (about LF conditions)!
During the transmission of "CU" in DFCW-600 i got a visit of a
very
kind man who wanted to take some photos of the great nature there.
Of
course he saw my high kite and asked what i am doing. Since he was
a CB
radio man in former times and works in the electric sector, he
predominantly understood what i am doing and was impressed by the
currently achieved world record and the whole setup and the
technical
data (such as Lambda=33km). So he took some nice photos and even
wrote
a report out of the view of a non VLF radio amateur which is
really
interesting to read. Here, some pictures are published as well.
See: http://mkorbit.de/2010/12/05/weltrekord-signalubertragung-auf-einer-langstwelle-vlf/
(in Geran language) If you want, just leave a comment there, he
would
be pleased by that i assume ;-)
Aftter a longer carrier and the message "CU" i moved to 5170 Hz.
Changing the wire to the other tap (550 mH) was a little dangerous
since the air was very dry and the wind seemed to carry charged
particles that caused a static voltage on the wire. I got sparks
of
about 10...15 mm and since the C is about 1.65 nF there was a
reasonable high energy on the wire. So i have to earth the antenna
by a
second cable befor removing the main wire. Anyway, QSY to 5170 Hz
took
about 2 minutes. After increasing the number of turns on the
loading
coil by about 12 i got some more antenna current on 5170 Hz, i.e.
about
530 mA. In the last experiment it was just 400 mA but i am still
not in
resonance. So it should be possible to get 800 mA there as well.
So, my
ERP on 5170 Hz was about 5 mW and the voltage about 9 kV
rms.
During the 5170 Hz transmission i prepared the LF/137 kHz
equipment but
i already gets dark slowly. So i haven't had much time on LF. Just
a
test to find the resonance and transmit some dashes that seemed to
appear on the UA4WPF grabber in 3009 km :-) Although i was playing
with
a 100W soldering iron there on the hill it was not possible to
make a
suitable tap on the correct place. Also, there was a resonance but
not
50 Ohms so it wasn't possible to use the class E PA but only a
class D
PA with very low power. Next time i will be better prepared and
will do
a experiment just on LF! :-)
After coming home in the dark i not even put the things out of my
car
but immediately fell in my bed ;-)
This was the 9th experiment and it was very exciting, funny, and
successful. No problems, nothing missed, good WX, a nice record
and
still some challenges left :-)
I hope to CU in the next experiment, probably in January 2011! :-)
Best 73, Stefan/DK7FC
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