MIME-Version: 1.0
Date: Tue, 16 Mar 2010 09:02:55 +0100 (CET)
Message-ID: <23519707.480708.1268726575403.JavaMail.fmail@mwmweb080>
References: <000001cac47a$f4ba1350$0202a8c0@laptopcore2>
 <E2DAF94B7561449DA86210B16A68F704@JimPC>,
 <38A51B74B884D74083D7950AD0DD85E82A1B57@File-Server-HST.hst.e-technik.tu-darmstadt.de>
From: =?ISO-8859-15?Q?Horst_St=F6cker?= <horst.stoecker@web.de>
To: rsgb_lf_group@blacksheep.org
In-Reply-To: <38A51B74B884D74083D7950AD0DD85E82A1B57@File-Server-HST.hst.e-technik.tu-darmstadt.de>
Importance: normal
Sensitivity: Normal
Subject: Congrats: LF: DK7FC's 2nd VLF TX test...
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: quoted-printable
Sender: owner-rsgb_lf_group@blacksheep.org
Precedence: bulk
Reply-To: rsgb_lf_group@blacksheep.org


Hello all
Congratulations to Stefan.=20
Mathematically it might have been clear that this is possible. Not really=
 my business, But YOU just DID it.
I was not with the doubters but I never had expected such success after su=
ch a short time. Just a few weeks ago I started the thread with a simple=
 question . more or less something like: Has someone crossed his garden fe=
nce below 9kHz, hi. The response was amazing.
Unbelievable that even the few experiments below 9kHz had stopped for such=
 a long time after the 90s, even in DL after the Bundesnetzagentur estimat=
ed that frequencies below 9kHz are free - but officially not ham radio. Th=
e few interested in this band have worked as single experimenters until th=
e discussion on the reflector became so encouraging. Real HAM radio!
I am happy with Stefan and also Markus. And I am looking forward to who of=
 us is next.
Horst


-----Urspr=C3=BCngliche Nachricht-----
Von: "Stefan Sch=C3=A4fer"=20
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,=20
>
>Thank you for your assistance on that very successful experiment! It is=
 a good day for the VLF ham operations and it won't be the last. YOU are=
 a part of this success since i wouldn't have done all the effort to becom=
e QRV there if you all wouldn't have been so interested in the discussion=
 about <9.=20
>
>So, perhaps there will come up further TX stns, i hope so. With the resul=
ts we can see what can be reached with a given ERP in a given distance. So=
, all the theoretical calculations become less speculative...
>
>First, i confirm that i was QRV to the described time at 8,9700kHz. =20
>
>I will detailed describe now what happend on this experiment.
>
>Starting with buying a plastic spray paint and fixing the windings on the=
 water barrel was the first work. Than applying the variometer and the pri=
mary coil.=20
>
>The primary coil is inductive coupled to the secondary and isolate mounte=
d on the bottom side of the water barrel. It has just 9 turns out of 4*0,4=
mm diameter isolated copper wire. The 9 turns was an estimation but later=
 it is shown that it is optimal for getting the maximum output power at mo=
derate voltages and currents.
>
>On http://www.qrz.com/db/DK7FC i will show many photos i have taken on th=
e hill. So there may come up some questions and some may be answered by th=
e pictures ;-)
>
>After building up the kite (the 8,1m^2 type due to a little unstable wind=
) and applying the whole equipment i started some resonating tests. The va=
riometer part has a litte too much L so it is sensitive to adjust but neve=
r mind. It was easy to resonate and after transmitting a long carrier i no=
ted that the heat sink of the PA remained absoultely cold. Then i increase=
d the output voltage and got an average DC current (PA input at 13,8VDC by=
 a SMPS driven by my fuel generator) of about 13A during the whole transmi=
ssion time. The PA still remained cold but it was fused with 10A and i had=
 a amperemeter of 20A full range, so i didn't further increase the power.=
 The current came up to 18A and go down to 9A during the kite movement.=20
>
>During the whole transmission, there were no HV problems! Just one time=
 the wind turned and suddenly the antenna wire got disconnected with a 8,9=
7kHz noisy 2cm long spark ;-) The DC current immediately decreased to < 1A=
 so that case is no problem for the PA.
>
>I was in telephone contact with Bernd/DF8ZR and started to transmit some=
 undefined sequences. Later i built up the notebook and installed the LF=
 sequencer and keyed the TX in QRSS30. Bernd copied it difficultly in a di=
stance of 16km. He clearly catched a 2 minutes transmission to that time=
 i transmitted it.=20
>
>I forgot to take the 1 Ohm current shunt resistor and the probe to watch/=
measure the current with the oscilloscope but later i rembered that i have=
 a "true rms" digital multimeter with a range up to 10 kHz and so i could=
 easily measure the accurent antenna current. The average antenna current=
 was about 480mA!
>
>So, the voltage was abt 15kV rms. Since there were no HV problems there=
 is the possibility to increase the ERP at least by 3dB.
>
>Andrey: No, the coil does almost not sing. The sound of the PA transforme=
r is louder (only a little, not too nerving) but all that is blown in the=
 wind ;-)
>
>Paul: My exact QTH is http://maps.google.de/maps?hl=3Dde&ie=3DUTF8&ll=3D4=
9.77647,8.699525&spn=3D0.001607,0.003428&t=3Dh&z=3D18 (see the coordinates=
 in the link). So: >Bearing of this signal was 117/297 deg.  Frankfurt is=
 on 114.  This is pretty exact! Congrats to your RX antenna system, Paul,=
 very fine!! So, what is the new WR? I do not have a program that calculat=
es the distance accuratly out of the coordinates...
>
>Later i got a mobile call from DF6NM who told me that the signal is visib=
le on his grabber. To that time i tried an unsuccessful QRSS10 test with=
 Bernd. Later i switched to QRSS120 to write "DK7FC/P" there but it took=
 2,5 hours just for these few letters. Finally i just transmitted "DKM" si=
nce during the "7" the antenna wire (copper+steel-litz) broke. You can cle=
arly see the "M" at the DF6NM grabber, the last sent letter for this day.=
 The broken wire was due to strong wind: The kite needs a braid that is el=
astic (110% length at maximum force) to withstand the wind blasts, so the=
 ant wire needs to have some sag and this sag was not enough in that momen=
t, so the whole force turned to the wire. No problem about the wire, i hav=
e enough for the next test...
>
>To the earth resistance: R(coil)=3D300Ohm and P(PA (with abt 100% efficie=
ncy))=3D180W, so the earth resistance seems to be about 480 Ohm. Hmm, seem=
s to be a little much but it includes all the other additional losses such=
 as coil losses due to the H stray field near the earth... I will measure=
 this more accurately the next time. BTW i measured the voltage waveform=
 with a loosely capacitive coupled HV probe. The sinus form was OK but cou=
ld be better. But the C coupling is a high pass and so the harmonics may=
 be not so strong as displayed... Listening to the harmonics with my IC706=
 gave nothing, nice.
>
>My first question (others surely will come up later): What is the achieva=
ble groundwave distance on the 33422m band? ;-) And what do you expect is=
 possible at night? Maybe, if we now have 830km (?, not 840?) we could eve=
n get much more...
>
>Maybe i have forgotten to answer some questions but this mail is already=
 long enough. 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