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Message-ID: <996785.96604.qm@web28105.mail.ukl.yahoo.com>
Date: Sun, 7 Mar 2010 05:41:23 -0800 (PST)
From: M0FMT <m0fmt@yahoo.co.uk>
To: rsgb_lf_group@blacksheep.org
In-Reply-To: <Pine.LNX.4.64.1003061659430.27602@plato.ucs.mun.ca>
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Subject: Re: LF: 12 km on Dream(ers) Band
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Well done Markus

You are an example to us all you have gone out there and done it. More str=
ength to you and thanks for a nice write up and picture... brilliant!!

73 es GL petefmt

--- On Sat, 6/3/10, jcraig@mun.ca <jcraig@mun.ca> wrote:


From: jcraig@mun.ca <jcraig@mun.ca>
Subject: Re: LF: 12 km on Dream(ers) Band
To: rsgb_lf_group@blacksheep.org
Date: Saturday, 6 March, 2010, 20:31


Congrats Markus and thank-you for providing the interesting details.

73
Joe VO1NA


On Sat, 6 Mar 2010, Markus Vester wrote:

> Dear LF,
>
> on two evenings this week, I have transmitted an 8.97 kHz signal from my=
 LF Marconi at home, and attempted to receive it at various locations. The=
 experiment was very similar to the one in April 2003, but with a moderate=
 improvement in ERP and FFT bandwidth. Now on both occasions, the carrier=
 could be detected at a distance of 12.1 km: http://www.mydarc.de/df6nm/vl=
f/vlf_12km.jpg
>
> My transmit antenna is relatively small, about 220 pF and 9 m effective=
 height at 137 kHz. Assuming a 20% reduction due to shielding, radiation=
 resistance would be around 74 microohms at 9 kHz. The 1.4 henry loading=
 coil is about 30 cm long by 12 cm diameter, and is split into seven sligh=
tly conical sections, partly inserted into one another (http://www.mydarc.=
de/df6nm/vlf/9kHz_aircoil.jpg). Each section has 700 turns of 0.2 mm ename=
led wire, total DC resistance is 830 ohms. Fine tuning is achieved by shif=
ting a thick block of ferrite into the last section. Using a 35 W car-radi=
o audio amplifier and a 1:32 ferrite transformer, I now got up to 0.135 A=
 and 11 kV rms at the antenna. Radiated power was thus approximately 1.3=
 uW (EMRP).
>




     =20

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<table cellspacing=3D"0" cellpadding=3D"0" border=3D"0" ><tr><td valign=3D=
"top" style=3D"font: inherit;"><DIV>Well done Markus<BR></DIV>
<DIV>You are an example to us all you have gone out there and done it. Mor=
e strength to you and thanks for a nice write up and picture... brilliant!=
!</DIV>
<DIV><BR>73 es GL petefmt<BR><BR>--- On <B>Sat, 6/3/10, jcraig@mun.ca <I>&=
lt;jcraig@mun.ca&gt;</I></B> wrote:<BR></DIV>
<BLOCKQUOTE style=3D"BORDER-LEFT: rgb(16,16,255) 2px solid; PADDING-LEFT:=
 5px; MARGIN-LEFT: 5px"><BR>From: jcraig@mun.ca &lt;jcraig@mun.ca&gt;<BR>S=
ubject: Re: LF: 12 km on Dream(ers) Band<BR>To: rsgb_lf_group@blacksheep.o=
rg<BR>Date: Saturday, 6 March, 2010, 20:31<BR><BR>
<DIV class=3DplainMail>Congrats Markus and thank-you for providing the int=
eresting details.<BR><BR>73<BR>Joe VO1NA<BR><BR><BR>On Sat, 6 Mar 2010, Ma=
rkus Vester wrote:<BR><BR>&gt; Dear LF,<BR>&gt;<BR>&gt; on two evenings th=
is week, I have transmitted an 8.97 kHz signal from my LF Marconi at home,=
 and attempted to receive it at various locations. The experiment was very=
 similar to the one in April 2003, but with a moderate improvement in ERP=
 and FFT bandwidth. Now on both occasions, the carrier could be detected=
 at a distance of 12.1 km: <A href=3D"http://www.mydarc.de/df6nm/vlf/vlf_1=
2km.jpg" target=3D_blank>http://www.mydarc.de/df6nm/vlf/vlf_12km.jpg</A><B=
R>&gt;<BR>&gt; My transmit antenna is relatively small, about 220 pF and=
 9 m effective height at 137 kHz. Assuming a 20% reduction due to shieldin=
g, radiation resistance would be around 74 microohms at 9 kHz. The 1.4 hen=
ry loading coil is about 30 cm long by 12 cm diameter, and is split into=
 seven slightly
 conical sections, partly inserted into one another (<A href=3D"http://www=
.mydarc.de/df6nm/vlf/9kHz_aircoil.jpg" target=3D_blank>http://www.mydarc.d=
e/df6nm/vlf/9kHz_aircoil.jpg</A>). Each section has 700 turns of 0.2 mm en=
ameled wire, total DC resistance is 830 ohms. Fine tuning is achieved by=
 shifting a thick block of ferrite into the last section. Using a 35 W car=
-radio audio amplifier and a 1:32 ferrite transformer, I now got up to 0.1=
35 A and 11 kV rms at the antenna. Radiated power was thus approximately=
 1.3 uW (EMRP).<BR>&gt;<BR><BR></DIV></BLOCKQUOTE></td></tr></table><br>



     =20

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