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Date: Tue, 23 Feb 2010 09:33:34 +0100
Message-ID: <38A51B74B884D74083D7950AD0DD85E82A1B10@File-Server-HST.hst.e-technik.tu-darmstadt.de>
Thread-Topic: LF: VLF_8.79 kHz
Thread-Index: Acq0GIn7qOGjdrJCSJCNmlH9LZZtUQABJI1+ABFxtog=
References: <260427.39843.qm@web28105.mail.ukl.yahoo.com> <38A51B74B884D74083D7950AD0DD85E82A1B0C@File-Server-HST.hst.e-technik.tu-darmstadt.de>
From: =?iso-8859-1?Q?Stefan_Sch=E4fer?= <schaefer@hst.tu-darmstadt.de>
To: <rsgb_lf_group@blacksheep.org>
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Subject: WG: LF: VLF_8.79 kHz
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Pete,=20
=20
Yesterday in the night or today in the morning i had another idea. The mai=
l wasn't reflected, perhaps too much data volume (sri, have forgotten to=
 delete the old mails hanging on)
=20
73, Stefan/DK7FC

________________________________

Von: Stefan Sch=E4fer
Gesendet: Di 23.02.2010 01:35
An: rsgb_lf_group@blacksheep.org
Betreff: AW: LF: VLF_8.79 kHz


Pete,=20
=20
A last idea for today (PC was already shut down but i cannot slep now ;-)=
 ):
=20
The very simpelst, maybe not the worst, way to try it on VLF is using your=
 inv L antenna as a real vertical loop.
=20
That means you could try to take a wire and connect it to the end of your=
 L, place it on the ground back to the feed point. Then, all you need is=
 a C, probably some 10 =B5F, to compensate the L of the wire at that frequ=
ency. The current will be limited just by the resistance of the antenna wi=
re, and the power of course. There will be no loading coil, so you reduce=
 much work!=20
=20
Perhaps the overall resistance will even be in the region of 4 Ohm, so you=
 do not even need a transformation! Just connect the ground wire to the gr=
ound of your amplifier and the top wire of the antenna in series with the=
 C to the AF output and adjust C for maximum antenna current (e.g. measure=
d by a 0,1 Ohm shunt resistor and an oscilloscope). That could be done in=
 1...3 hours of work :-)
=20
If your signal will be received in 6,5km, you could tell us the difference=
 to the before mentioned ways of matching. And: Since Jacek has reached 75=
0m with 2W TX power and a 4m*14m loop, you could be successful with 100W=
 and a vertical loop with more area and QRSS...
=20
GL!! Stefan/DK7FC
=20

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<BODY>
<DIV dir=3Dltr id=3DidOWAReplyText61758>
<DIV dir=3Dltr><FONT color=3D#000000 size=3D2 face=3DArial>Pete, </FONT></=
DIV>
<DIV dir=3Dltr><FONT size=3D2 face=3DArial></FONT>&nbsp;</DIV>
<DIV dir=3Dltr><FONT size=3D2 face=3DArial>Yesterday in the night or&nbsp;=
today in the morning i had another idea. The mail wasn't reflected, perhap=
s too much data volume (sri, have forgotten to delete the old mails hangin=
g on)</FONT></DIV>
<DIV dir=3Dltr><FONT size=3D2 face=3DArial></FONT>&nbsp;</DIV>
<DIV dir=3Dltr><FONT size=3D2 face=3DArial>73, Stefan/DK7FC</FONT></DIV></=
DIV>
<DIV dir=3Dltr><BR>
<HR tabIndex=3D-1>
<FONT size=3D2 face=3DTahoma><B>Von:</B> Stefan Sch=E4fer<BR><B>Gesendet:<=
/B> Di 23.02.2010 01:35<BR><B>An:</B> rsgb_lf_group@blacksheep.org<BR><B>B=
etreff:</B> AW: LF: VLF_8.79 kHz<BR></FONT><BR></DIV>
<DIV dir=3Dltr>
<DIV dir=3Dltr id=3DidOWAReplyText6951>
<DIV dir=3Dltr><FONT color=3D#000000 size=3D2 face=3DArial>Pete, </FONT></=
DIV>
<DIV dir=3Dltr><FONT size=3D2 face=3DArial></FONT>&nbsp;</DIV>
<DIV dir=3Dltr><FONT size=3D2 face=3DArial>A last idea for today (PC was=
 already shut down but i cannot slep now ;-) ):</FONT></DIV>
<DIV dir=3Dltr><FONT size=3D2 face=3DArial></FONT>&nbsp;</DIV>
<DIV dir=3Dltr><FONT size=3D2 face=3DArial>The very simpelst, maybe not th=
e&nbsp;worst, way to try it on VLF is using your inv L antenna as a real=
 vertical loop.</FONT></DIV>
<DIV dir=3Dltr><FONT size=3D2 face=3DArial></FONT>&nbsp;</DIV>
<DIV dir=3Dltr><FONT size=3D2 face=3DArial>That means you could try to tak=
e a wire and connect it to the end of your L, place it on the ground back=
 to the feed point. Then, all you need is a C, probably some 10 =B5F, to=
 compensate the L of the wire at that frequency. The current will be limit=
ed just by the resistance of the antenna wire, and the power of course. Th=
ere will be no loading coil, so you reduce much work! </FONT></DIV>
<DIV dir=3Dltr><FONT size=3D2 face=3DArial></FONT>&nbsp;</DIV>
<DIV dir=3Dltr><FONT size=3D2 face=3DArial>Perhaps the overall resistance=
 will even be in the region of 4 Ohm, so you do not even need a transforma=
tion! Just connect the ground wire to the ground of your amplifier and the=
 top wire of the antenna in series with the C to the AF output and adjust=
 C for maximum antenna current (e.g. measured by a 0,1 Ohm shunt resistor=
 and an oscilloscope). That could be done in 1...3 hours of work :-)</FONT=
></DIV>
<DIV dir=3Dltr><FONT size=3D2 face=3DArial></FONT>&nbsp;</DIV>
<DIV dir=3Dltr><FONT size=3D2 face=3DArial>If your signal will be received=
 in 6,5km, you could tell us the difference to the before mentioned ways=
 of matching. And: Since Jacek has reached 750m with 2W TX power and a 4m*=
14m loop, you could be successful with 100W and a vertical loop with more=
 area and QRSS...</FONT></DIV>
<DIV dir=3Dltr><FONT size=3D2 face=3DArial></FONT>&nbsp;</DIV>
<DIV dir=3Dltr><FONT size=3D2 face=3DArial>GL!! Stefan/DK7FC</FONT></DIV><=
/DIV>
<DIV dir=3Dltr>&nbsp;</DIV></DIV></BODY></HTML>

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