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Date: Mon, 02 Aug 2010 18:43:05 +0200
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Subject: Re: VLF: DK7FC's 6th VLF kite experiment
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Hello Michel,

Thank you very much for the interest and the appempt to catch the=20
signal. It's the first time i read something from you (regarding the VLF=
=20
tests) and i am generally impressed by the amount of people in so many=20
different countries who are present here on this reflector. The=20
reflector gives the feeling as something private and/or collective, not=20
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=20
my transmission very well! Sadly i have not transmitted a real=20
character, such as "K" or "C" or so. But your trace is stable in=20
frequency! This is not the case for the most signals on VLF!=20
Additionally, the trace shows the typical frequency offset of my DDS=20
VFO, about 30...40 mHz lower than in  the display! This are all=20
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=20
would say yes.
You can imagine how the reception would have been some hours earlier,=20
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 wa=
s'nt
> succesful so far. However, this time, i got some faint traces I'm not ab=
le 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 usin=
g a
> LC 7th order low pass filter to improve the dynamic range of the system.
>
> 73,
>
> Michel - F5WK  in JN18HP
>
> Le lundi 2 ao=FBt 2010 =E0 13:01:32, vous =E9criviez :
>
>   =20
>> Dear LF/VLF group,
>>     =20
>   =20
>> 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 mak=
es
>> 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 situatio=
n.
>> This is an important feedback as well and much more interesting than ju=
st having a mobile internet stick.
>>     =20
>   =20
>> 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 dai=
ly
>> maximum as i was able to transmit at a high kite angle. The QRN was eve=
n
>> 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 acti=
ve
>> antenna for 137 that will not be too much swayed be the TX antenna...
>>     =20
>   =20
>> As far as i can see there was a positive reception at least by the foll=
owing 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)
>>     =20
>   =20
>> 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!
>>     =20
>
>   =20
>> Now, i want to give a detailed report of the things that happened on th=
e TX side:
>>     =20
>   =20
>> 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.
>>     =20
>   =20
>> 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 increas=
ed
>> 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 th=
e
>> 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 germa=
n
>> 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.
>>     =20
>   =20
>> 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 =80 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 oth=
er
>> 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 th=
ere
>> was a heavy pull on it. The braid stopped in a beginning corner of a co=
rn
>> field and as i lifted it above the corn it sounded like a lash/whip. Bu=
t
>> suddenly the kite came out of the tree and before it dropped on the bot=
tom
>> 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...
>>     =20
>   =20
>> 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 limpl=
e
>> 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.
>>     =20
>   =20
>> 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.
>>     =20
>   =20
>> 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.
>>     =20
>   =20
>> 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 amateu=
rs
>>     =20
>   =20
>> 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 receptio=
ns
>> and can be very hopefully that this can be much improved in the next te=
st,
>> if there is proper wind and less QRN that can be assumed when going to=
 the autumn
>>     =20
>   =20
>> Again thanks to all the group and hope cuagn in the next test!
>>     =20
>   =20
>> Best 73, Stefan/DK7FC
>>     =20
>   =20
>> PS: Some photos and screenshots will be displayed on my QRZ.com page in=
 some days.
>>     =20
>   =20
>> PPS: Hopefully there will come up further stations on the dreamers band=
 within this year
>>     =20
>
>
>
>
>
>
>
>   =20