Message-ID: <001701cb29c2$3b42f830$0401a8c0@xphd97xgq27nyf>
From: "mal hamilton" <g3kevmal@talktalk.net>
To: "rsgb" <rsgb_lf_group@blacksheep.org>
Date: Thu, 22 Jul 2010 18:20:49 +0100
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Subject: LF: Fw: earth antenna
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----- Original Message -----=20
From: mal hamilton=20
To: rsgb_lf_group@blacksheep.org=20
Sent: Tuesday, July 20, 2010 6:58 PM
Subject: Re: earth antenna


Stefan
Keep climbing until you get enough height for an airborne Antenna., tr=
y a 300metre tree in the black forest, I might hear you then

g3kev

  ----- Original Message -----=20
  From: Stefan Sch=E4fer=20
  To: rsgb_lf_group@blacksheep.org=20
  Sent: Tuesday, July 20, 2010 6:50 PM
  Subject: VLF: earth antenna


  Dear VLF,

  Today i was in the forest for more than 10 hours doing the following=
 tests/works :-) :

  Today i did my test on 8,97 and 7,97 and 6,97 kHz. It was possible=
 to transmit on the lower frequencies like one can still see on my gra=
bber2. The antenna current was just about 220 mA and 130mA in the 8,97=
 test. There were some problems with a step up transformer in combinat=
ion with the big PA, thus the low current (i used a 12V/150V DC/DC con=
verter and batteries, not my generator for high power). So the signal=
 was even 3 dB lower than in the "73" test on 8,97 before some weeks.=
 On 8,97 the power was 8 dB lower, thus there was no reception on 8,97=
 today but as we know, it works best on 8,97 in 5km distance. The lowe=
r the frequency the more i am again in the near field. This improves=
 the propagation i suppose.

  If my 5 km distance could be "utility assisted" like in Rogers tests=
 is not sure. A wider distance reception has to be done!

  After that i increased the earth antenna length to 500m, 420m ground=
 electrode spacing!! :-) The average height above ground is still abou=
t 4m. Orientation of the antenna is N<=3D>S.
  This was a hard work since i had to climb many trees since i had to=
 cross 2 ways in a hight of about 6m. Since it is a conferous forest,=
 i have 100s of scratches now but all in all it was a inspiring work=
 :-).
  I removed the far ends ground rods and will place them on the new en=
d that will be found on thursday! Adding the last 200m part will be ra=
ther easy since there are no ways to cross any more and the tree-densi=
ty is rather low ;-) Than, i will have a 700m long wire and the ground=
 electrode distance will be about 600m!! With that antenna i will try=
 to be received in 50km distance on 8,97 kHz when Michael Oexner is co=
ming back from holidays in abt 2 weeks.=20
  Before this test i will try to reduce the overall losses below 500=
 Ohm and do some RX tests watching the new VLF transmitter levels (DHO=
38 and so on).

  Any bets about the signal increase when increasing the spacing from=
 280m to 600m?

  73, Stefan/DK7FC


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<META http-equiv=3DContent-Type content=3D"text/html; charset=3DISO-88=
59-1">
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<DIV>&nbsp;</DIV>
<DIV style=3D"FONT: 10pt arial">----- Original Message -----=20
<DIV style=3D"BACKGROUND: #e4e4e4; font-color: black"><B>From:</B> <A=
   title=3Dg3kevmal@talktalk.net href=3D"mailto:g3kevmal@talktalk.net"=
>mal hamilton</A>=20
</DIV>
<DIV><B>To:</B> <A title=3Drsgb_lf_group@blacksheep.org   href=3D"mail=
to:rsgb_lf_group@blacksheep.org">rsgb_lf_group@blacksheep.org</A>=20
</DIV>
<DIV><B>Sent:</B> Tuesday, July 20, 2010 6:58 PM</DIV>
<DIV><B>Subject:</B> Re: earth antenna</DIV></DIV>
<DIV><BR></DIV>
<DIV><FONT face=3DArial size=3D2>Stefan</FONT></DIV>
<DIV><FONT face=3DArial size=3D2>Keep climbing until you get enough he=
ight for an=20
airborne Antenna., try a 300metre tree in the black forest, I might he=
ar you=20
then</FONT></DIV>
<DIV>&nbsp;</DIV>
<DIV><FONT face=3DArial size=3D2>g3kev</FONT></DIV>
<DIV><FONT face=3DArial size=3D2></FONT>&nbsp;</DIV>
<BLOCKQUOTE   style=3D"PADDING-RIGHT: 0px; PADDING-LEFT: 5px; MARGIN-L=
EFT: 5px; BORDER-LEFT: #000000 2px solid; MARGIN-RIGHT: 0px">
  <DIV style=3D"FONT: 10pt arial">----- Original Message ----- </DIV>
  <DIV     style=3D"BACKGROUND: #e4e4e4; FONT: 10pt arial; font-color:=
 black"><B>From:</B>=20
  <A title=3Dschaefer@iup.uni-heidelberg.de     href=3D"mailto:schaefe=
r@iup.uni-heidelberg.de">Stefan Sch=E4fer</A> </DIV>
  <DIV style=3D"FONT: 10pt arial"><B>To:</B> <A title=3Drsgb_lf_group@=
blacksheep.org     href=3D"mailto:rsgb_lf_group@blacksheep.org">rsgb_l=
f_group@blacksheep.org</A>=20
  </DIV>
  <DIV style=3D"FONT: 10pt arial"><B>Sent:</B> Tuesday, July 20, 2010=
 6:50=20
PM</DIV>
  <DIV style=3D"FONT: 10pt arial"><B>Subject:</B> VLF: earth antenna</=
DIV>
  <DIV><BR></DIV>Dear VLF,<BR><BR>Today i was in the forest for more=
 than 10=20
  hours doing the following tests/works :-) :<BR><BR>Today i did my te=
st on=20
  <B>8,97 and 7,97 and 6,97 kHz</B>. It was possible to transmit on th=
e lower=20
  frequencies like one can still see on my grabber2. The antenna curre=
nt was=20
  just about 220 mA and 130mA in the 8,97 test. There were some proble=
ms with a=20
  step up transformer in combination with the big PA, thus the low cur=
rent (i=20
  used a 12V/150V DC/DC converter and batteries, not my generator for=
 high=20
  power). So the signal was even 3 dB lower than in the "73" test on=
 8,97 before=20
  some weeks. On 8,97 the power was 8 dB lower, thus there was no rece=
ption on=20
  8,97 today but as we know, it works best on 8,97 in 5km distance. Th=
e lower=20
  the frequency the more i am again in the near field. This improves=
 the=20
  propagation i suppose.<BR><BR>If my 5 km distance could be "utility=
 assisted"=20
  like in Rogers tests is not sure. A wider distance reception has to=
 be=20
  done!<BR><BR>After that i increased the <B>earth antenna length to=
 500m, 420m=20
  ground electrode spacing</B>!! :-) The average height above ground=
 is still=20
  about 4m. Orientation of the antenna is N&lt;=3D&gt;S.<BR>This was=
 a hard work=20
  since i had to climb many trees since i had to cross 2 ways in a hig=
ht of=20
  about 6m. Since it is a conferous forest, i have 100s of scratches=
 now but all=20
  in all it was a inspiring work :-).<BR>I removed the far ends ground=
 rods and=20
  will place them on the new end that will be found on thursday! Addin=
g the last=20
  200m part will be rather easy since there are no ways to cross any=
 more and=20
  the tree-density is rather low ;-) Than, i will have a 700m long wir=
e and the=20
  ground electrode distance will be about 600m!! With that antenna i=
 will try to=20
  be received in 50km distance on 8,97 kHz when Michael Oexner is comi=
ng back=20
  from holidays in abt 2 weeks. <BR>Before this test i will try to red=
uce the=20
  overall losses below 500 Ohm and do some RX tests watching the new=
 VLF=20
  transmitter levels (DHO38 and so on).<BR><BR>Any bets about the sign=
al=20
  increase when increasing the spacing from 280m to 600m?<BR><BR>73,=
=20
  Stefan/DK7FC<BR><BR></BLOCKQUOTE></BODY></HTML>

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