Date: Tue, 16 Mar 2010 10:00:38 +0100
To: "rsgb_lf_group@blacksheep.org" <rsgb_lf_group@blacksheep.org>
From: Rik Strobbe <rik.strobbe@fys.kuleuven.be>
In-Reply-To: <23519707.480708.1268726575403.JavaMail.fmail@mwmweb080>
References: <000001cac47a$f4ba1350$0202a8c0@laptopcore2>
 <E2DAF94B7561449DA86210B16A68F704@JimPC>
 <38A51B74B884D74083D7950AD0DD85E82A1B57@File-Server-HST.hst.e-technik.tu-darmstadt.de>
 <23519707.480708.1268726575403.JavaMail.fmail@mwmweb080>
Mime-Version: 1.0
Message-Id: <20100316090031.97A14F3862@smtps02.kuleuven.be>
Subject: Re: Congrats: LF: DK7FC's 2nd VLF TX test...
Content-Type: text/plain; charset="iso-8859-1"; format=flowed
Content-Transfer-Encoding: quoted-printable
Sender: owner-rsgb_lf_group@blacksheep.org
Precedence: bulk
Reply-To: rsgb_lf_group@blacksheep.org


Also my congrats to all involved. If things=20
continue to proceed at this speed (within some=20
weeks from pure theoretical thoughts to a=20
reception at over 800km) the big pond should be crossed by Easter ;-).
I had a look at Markus LF grabber and noticed a=20
clear "dip" in background noise around noon, maybe this is the right time=
 ?

73, Rik  ON7YD - OR7T

At 09:02 16/03/2010, you wrote:
>Hello all
>Congratulations to Stefan.
>Mathematically it might have been clear that=20
>this is possible. Not really my business, But YOU just DID it.
>I was not with the doubters but I never had=20
>expected such success after such a short time.=20
>Just a few weeks ago I started the thread with a=20
>simple question . more or less something like:=20
>Has someone crossed his garden fence below 9kHz, hi. The response was ama=
zing.
>Unbelievable that even the few experiments below=20
>9kHz had stopped for such a long time after the=20
>90s, even in DL after the Bundesnetzagentur=20
>estimated that frequencies below 9kHz are free -=20
>but officially not ham radio. The few interested=20
>in this band have worked as single experimenters=20
>until the discussion on the reflector became so encouraging. Real HAM rad=
io!
>I am happy with Stefan and also Markus. And I am=20
>looking forward to who of us is next.
>Horst
>
>
>-----Urspr=C3=BCngliche Nachricht-----
>Von: "Stefan Sch=C3=A4fer"
>Gesendet: 16.03.2010 01:15:17
>An: rsgb_lf_group@blacksheep.org
>Betreff: AW: LF: DK7FC's 2nd VLF TX test...
>
> >Dear LF group, RXers and 9Dreamers and doubters,
> >
> >Thank you for your assistance on that very=20
> successful experiment! It is a good day for the=20
> VLF ham operations and it won't be the last.=20
> YOU are a part of this success since i wouldn't=20
> have done all the effort to become QRV there if=20
> you all wouldn't have been so interested in the discussion about <9.
> >
> >So, perhaps there will come up further TX=20
> stns, i hope so. With the results we can see=20
> what can be reached with a given ERP in a given=20
> distance. So, all the theoretical calculations become less speculative..=
.
> >
> >First, i confirm that i was QRV to the described time at 8,9700kHz.
> >
> >I will detailed describe now what happend on this experiment.
> >
> >Starting with buying a plastic spray paint and=20
> fixing the windings on the water barrel was the=20
> first work. Than applying the variometer and the primary coil.
> >
> >The primary coil is inductive coupled to the=20
> secondary and isolate mounted on the bottom=20
> side of the water barrel. It has just 9 turns=20
> out of 4*0,4mm diameter isolated copper wire.=20
> The 9 turns was an estimation but later it is=20
> shown that it is optimal for getting the=20
> maximum output power at moderate voltages and currents.
> >
> >On http://www.qrz.com/db/DK7FC i will show=20
> many photos i have taken on the hill. So there=20
> may come up some questions and some may be answered by the pictures ;-)
> >
> >After building up the kite (the 8,1m^2 type=20
> due to a little unstable wind) and applying the=20
> whole equipment i started some resonating=20
> tests. The variometer part has a litte too much=20
> L so it is sensitive to adjust but never mind.=20
> It was easy to resonate and after transmitting=20
> a long carrier i noted that the heat sink of=20
> the PA remained absoultely cold. Then i=20
> increased the output voltage and got an average=20
> DC current (PA input at 13,8VDC by a SMPS=20
> driven by my fuel generator) of about 13A=20
> during the whole transmission time. The PA=20
> still remained cold but it was fused with 10A=20
> and i had a amperemeter of 20A full range, so i=20
> didn't further increase the power. The current=20
> came up to 18A and go down to 9A during the kite movement.
> >
> >During the whole transmission, there were no=20
> HV problems! Just one time the wind turned and=20
> suddenly the antenna wire got disconnected with=20
> a 8,97kHz noisy 2cm long spark ;-) The DC=20
> current immediately decreased to < 1A so that case is no problem for the=
 PA.
> >
> >I was in telephone contact with Bernd/DF8ZR=20
> and started to transmit some undefined=20
> sequences. Later i built up the notebook and=20
> installed the LF sequencer and keyed the TX in=20
> QRSS30. Bernd copied it difficultly in a=20
> distance of 16km. He clearly catched a 2=20
> minutes transmission to that time i transmitted it.
> >
> >I forgot to take the 1 Ohm current shunt=20
> resistor and the probe to watch/measure the=20
> current with the oscilloscope but later i=20
> rembered that i have a "true rms" digital=20
> multimeter with a range up to 10 kHz and so i=20
> could easily measure the accurent antenna=20
> current. The average antenna current was about 480mA!
> >
> >So, the voltage was abt 15kV rms. Since there=20
> were no HV problems there is the possibility to=20
> increase the ERP at least by 3dB.
> >
> >Andrey: No, the coil does almost not sing. The=20
> sound of the PA transformer is louder (only a=20
> little, not too nerving) but all that is blown in the wind ;-)
> >
> >Paul: My exact QTH is=20
> http://maps.google.de/maps?hl=3Dde&ie=3DUTF8&ll=3D49.77647,8.699525&spn=
=3D0.001607,0.003428&t=3Dh&z=3D18=20
> (see the coordinates in the link). So: >Bearing=20
> of this signal was 117/297 deg.  Frankfurt is=20
> on 114.  This is pretty exact! Congrats to your=20
> RX antenna system, Paul, very fine!! So, what=20
> is the new WR? I do not have a program that=20
> calculates the distance accuratly out of the coordinates...
> >
> >Later i got a mobile call from DF6NM who told=20
> me that the signal is visible on his grabber.=20
> To that time i tried an unsuccessful QRSS10=20
> test with Bernd. Later i switched to QRSS120 to=20
> write "DK7FC/P" there but it took 2,5 hours=20
> just for these few letters. Finally i just=20
> transmitted "DKM" since during the "7" the=20
> antenna wire (copper+steel-litz) broke. You can=20
> clearly see the "M" at the DF6NM grabber, the=20
> last sent letter for this day. The broken wire=20
> was due to strong wind: The kite needs a braid=20
> that is elastic (110% length at maximum force)=20
> to withstand the wind blasts, so the ant wire=20
> needs to have some sag and this sag was not=20
> enough in that moment, so the whole force=20
> turned to the wire. No problem about the wire,=20
> i have enough for the next test...
> >
> >To the earth resistance: R(coil)=3D300Ohm and=20
> P(PA (with abt 100% efficiency))=3D180W, so the=20
> earth resistance seems to be about 480 Ohm.=20
> Hmm, seems to be a little much but it includes=20
> all the other additional losses such as coil=20
> losses due to the H stray field near the=20
> earth... I will measure this more accurately=20
> the next time. BTW i measured the voltage=20
> waveform with a loosely capacitive coupled HV=20
> probe. The sinus form was OK but could be=20
> better. But the C coupling is a high pass and=20
> so the harmonics may be not so strong as=20
> displayed... Listening to the harmonics with my IC706 gave nothing, nice=
.
> >
> >My first question (others surely will come up=20
> later): What is the achievable groundwave=20
> distance on the 33422m band? ;-) And what do=20
> you expect is possible at night? Maybe, if we=20
> now have 830km (?, not 840?) we could even get much more...
> >
> >Maybe i have forgotten to answer some=20
> questions but this mail is already long enough.=20
> So, will go on tomorrow. Now uploading the pics...
> >
> >73 es GL, GN, 9 dreaming...
> >
> >Stefan/DK7FC
> >
> >
>___________________________________________________________
>GRATIS f=C3=BCr alle WEB.DE-Nutzer: Die maxdome Movie-FLAT!
>Jetzt freischalten unter http://movieflat.web.de