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Date: Tue, 16 Mar 2010 06:40:27 +0000
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From: Roger Lapthorn <rogerlapthorn@gmail.com>
To: rsgb_lf_group@blacksheep.org
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Subject: Re: LF: DK7FC's 2nd VLF TX test...
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*Testing on the 33km band*

Where does one start?*

*
*Stefan* - this is simply BRILLIANT experimental work. Thank you for your
hard work and for sharing it with us here. I wish you and everyone else al=
l
the very best in pursuing this further. Clearly this is just the start.

*Paul, Marcus* etc - thanks for watching at the other end and making the
screen shots.

*Mal -* your comments are noted, but I think there is little room for doub=
t
that the signals received were from Stefan. It will be good to get a full
and positive identification in a later test everyone would clearly agree.
Everyone is now awaiting your big signal on this band from the UK.

And to think I get excited over a few hundred kilometres on 500kHz.

Wow!! This has been *so* exciting to follow.

73s
Roger G3XBM



2010/3/16 Stefan Sch=E4fer <schaefer@hst.tu-darmstadt.de>

> Dear LF group, RXers and 9Dreamers and doubters,
>
> 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 become QRV
> there if you all wouldn't have been so interested in the discussion abou=
t
> <9.
>
> So, perhaps there will come up further TX stns, i hope so. With the resu=
lts
> 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.
>
> I will detailed describe now what happend on this experiment.
>
> Starting with buying a plastic spray paint and fixing the windings on th=
e
> water barrel was the first work. Than applying the variometer and the
> primary coil.
>
> The primary coil is inductive coupled to the secondary and isolate mount=
ed
> 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 moderat=
e
> voltages and currents.
>
> On http://www.qrz.com/db/DK7FC i will show many photos i have taken on=
 the
> 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 win=
d)
> and applying the whole equipment i started some resonating tests. The
> variometer part has a litte too much L so it is sensitive to adjust but
> never mind. It was easy to resonate and after transmitting a long carrie=
r i
> noted that the heat sink of the PA remained absoultely cold. Then i
> increased 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
> transmission 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.
>
> During the whole transmission, there were no HV problems! Just one time=
 the
> wind turned and suddenly the antenna wire got disconnected with a 8,97kH=
z
> 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
> distance of 16km. He clearly catched a 2 minutes transmission to that ti=
me i
> transmitted it.
>
> 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 tha=
t 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 transform=
er
> 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=3D49.77647,8.699525&spn=
=3D0.001607,0.003428&t=3Dh&z=3D18(see the coordinates in the link). So: >B=
earing 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 calculates the distance accuratly out of the coordinates...
>
> Later i got a mobile call from DF6NM who told me that the signal is visi=
ble
> on his grabber. To that time i tried an unsuccessful QRSS10 test with Be=
rnd.
> Later i switched to QRSS120 to write "DK7FC/P" there but it took 2,5 hou=
rs
> just for these few letters. Finally i just transmitted "DKM" since durin=
g
> the "7" the antenna wire (copper+steel-litz) broke. You can clearly 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 elastic (110% len=
gth
> 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 moment, so the whole=
 force
> turned to the wire. No problem about the wire, i have enough for the nex=
t
> test...
>
> To the earth resistance: R(coil)=3D300Ohm and P(PA (with abt 100%
> efficiency))=3D180W, so the earth resistance seems to be about 480 Ohm.=
 Hmm,
> seems to be a little much but it includes all the other additional losse=
s
> 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 could be better. But the C coupling is a high pass and so the harmon=
ics
> 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
> achievable 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 even 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
>
>


--=20

http://g3xbm-qrp.blogspot.com/
http://www.g3xbm.co.uk
http://www.youtube.com/user/G3XBM
G3XBM    GQRP 1678      ISWL G11088

--00151758aa6ce722a40481e545cd
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<b><u>Testing on the 33km band</u></b><br><br>Where does one start?<b><br>=
<br></b><div style=3D"margin-left: 40px;"><b>Stefan</b> - this is simply=
 BRILLIANT experimental work. Thank you for your hard work and for sharing=
 it with us here. I wish you and everyone else all the very best in pursui=
ng this further. Clearly this is just the start.<br>
<br><b>Paul, Marcus</b> etc - thanks for watching at the other end and mak=
ing the screen shots.<br><br><b>Mal -</b> your comments are noted, but I=
 think there is little room for doubt that the signals received were from=
 Stefan. It will be good to get a full and positive identification in a la=
ter test everyone would clearly agree. Everyone is now awaiting your big=
 signal on this band from the UK.<br>
</div>
<br>And to think I get excited over a few hundred kilometres on 500kHz.<br=
><br>Wow!! This has been <i>so</i> exciting to follow.<br><br>73s<br>Roger=
 G3XBM<br><br><br><br><div class=3D"gmail_quote">2010/3/16 Stefan Sch=E4fe=
r <span dir=3D"ltr">&lt;<a href=3D"mailto:schaefer@hst.tu-darmstadt.de">sc=
haefer@hst.tu-darmstadt.de</a>&gt;</span><br>
<blockquote class=3D"gmail_quote" style=3D"margin: 0pt 0pt 0pt 0.8ex; bord=
er-left: 1px solid rgb(204, 204, 204); padding-left: 1ex;">Dear LF group,=
 RXers and 9Dreamers and doubters,<br>
<br>
Thank you for your assistance on that very successful experiment! It is a=
 good day for the VLF ham operations and it won&#39;t be the last. YOU are=
 a part of this success since i wouldn&#39;t have done all the effort to=
 become QRV there if you all wouldn&#39;t have been so interested in the=
 discussion about &lt;9.<br>

<br>
So, perhaps there will come up further TX stns, i hope so. With the result=
s we can see what can be reached with a given ERP in a given distance. So,=
 all the theoretical calculations become less speculative...<br>
<br>
First, i confirm that i was QRV to the described time at 8,9700kHz.<br>
<br>
I will detailed describe now what happend on this experiment.<br>
<br>
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.<br>
<br>
The primary coil is inductive coupled to the secondary and isolate mounted=
 on the bottom side of the water barrel. It has just 9 turns out of 4*0,4m=
m 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.<br>

<br>
On <a href=3D"http://www.qrz.com/db/DK7FC" target=3D"_blank">http://www.qr=
z.com/db/DK7FC</a> i will show many photos i have taken on the hill. So th=
ere may come up some questions and some may be answered by the pictures ;-=
)<br>

<br>
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 var=
iometer part has a litte too much L so it is sensitive to adjust but never=
 mind. It was easy to resonate and after transmitting a long carrier i not=
ed that the heat sink of the PA remained absoultely cold. Then i increased=
 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&#39;t further increase the pow=
er. The current came up to 18A and go down to 9A during the kite movement.=
<br>

<br>
During the whole transmission, there were no HV problems! Just one time th=
e wind turned and suddenly the antenna wire got disconnected with a 8,97kH=
z noisy 2cm long spark ;-) The DC current immediately decreased to &lt; 1A=
 so that case is no problem for the PA.<br>

<br>
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.<br>

<br>
I forgot to take the 1 Ohm current shunt resistor and the probe to watch/m=
easure the current with the oscilloscope but later i rembered that i have=
 a &quot;true rms&quot; digital multimeter with a range up to 10 kHz and=
 so i could easily measure the accurent antenna current. The average anten=
na current was about 480mA!<br>

<br>
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.<br>
<br>
Andrey: No, the coil does almost not sing. The sound of the PA transformer=
 is louder (only a little, not too nerving) but all that is blown in the=
 wind ;-)<br>
<br>
Paul: My exact QTH is <a href=3D"http://maps.google.de/maps?hl=3Dde&amp;ie=
=3DUTF8&amp;ll=3D49.77647,8.699525&amp;spn=3D0.001607,0.003428&amp;t=3Dh&a=
mp;z=3D18" target=3D"_blank">http://maps.google.de/maps?hl=3Dde&amp;ie=3DU=
TF8&amp;ll=3D49.77647,8.699525&amp;spn=3D0.001607,0.003428&amp;t=3Dh&amp;z=
=3D18</a> (see the coordinates in the link). So: &gt;Bearing of this signa=
l was 117/297 deg. =A0Frankfurt is on 114. =A0This is pretty exact! Congra=
ts to your RX antenna system, Paul, very fine!! So, what is the new WR? I=
 do not have a program that calculates the distance accuratly out of the=
 coordinates...<br>

<br>
Later i got a mobile call from DF6NM who told me that the signal is visibl=
e on his grabber. To that time i tried an unsuccessful QRSS10 test with Be=
rnd. Later i switched to QRSS120 to write &quot;DK7FC/P&quot; there but it=
 took 2,5 hours just for these few letters. Finally i just transmitted &qu=
ot;DKM&quot; since during the &quot;7&quot; the antenna wire (copper+steel=
-litz) broke. You can clearly see the &quot;M&quot; 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 elastic (110% length at maximum force) to=
 withstand the wind blasts, so the ant wire needs to have some sag and thi=
s sag was not enough in that moment, so the whole force turned to the wire=
. No problem about the wire, i have enough for the next test...<br>

<br>
To the earth resistance: R(coil)=3D300Ohm and P(PA (with abt 100% efficien=
cy))=3D180W, so the earth resistance seems to be about 480 Ohm. Hmm, seems=
 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.<br>

<br>
My first question (others surely will come up later): What is the achievab=
le 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...<br>

<br>
Maybe i have forgotten to answer some questions but this mail is already=
 long enough. So, will go on tomorrow. Now uploading the pics...<br>
<br>
73 es GL, GN, 9 dreaming...<br>
<br>
Stefan/DK7FC<br>
<br>
</blockquote></div><br><br clear=3D"all"><br>-- <br><br><a href=3D"http://=
g3xbm-qrp.blogspot.com/">http://g3xbm-qrp.blogspot.com/</a><br><a href=3D"=
http://www.g3xbm.co.uk">http://www.g3xbm.co.uk</a><br><a href=3D"http://ww=
w.youtube.com/user/G3XBM">http://www.youtube.com/user/G3XBM</a><br>
G3XBM =A0 =A0GQRP 1678 =A0 =A0 =A0ISWL G11088<br>

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