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Date: Thu, 28 Jun 2012 17:00:43 +0100 (BST)
From: Daniele Tincani <danieletincani@yahoo.com>
To: "rsgb_lf_group@blacksheep.org" <rsgb_lf_group@blacksheep.org>
In-Reply-To: <4FEC76C8.9040700@iup.uni-heidelberg.de>
MIME-Version: 1.0
Subject: Re: LF: Coupling a LF resonant ferrite rx antenna
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Hello Stefan, your hand-sketched schematics (and also the way you=A0built=
=A0the antenna,=A0etc.)=A0look just like my idea of the final result I woul=
d like to obtain. BTW I still have some BF862s from my experiments with you=
r VLF E-probe :-) I think I would try to replicate your example.=0A73=0ADan=
iele IZ5WWB=0A =0A=0A________________________________=0A Da: Stefan Sch=E4f=
er <Stefan.Schaefer@iup.uni-heidelberg.de>=0AA: rsgb_lf_group@blacksheep.or=
g =0AInviato: Gioved=EC 28 Giugno 2012 17:22=0AOggetto: Re: LF: Coupling a =
LF resonant ferrite rx antenna=0A  =0A=0A =0APS: For a 50 Ohm output, just =
2 or 3 turns on the out-coupling winding=0Awas the best choice for my ferri=
te antenna.=0A=0AAm 28.06.2012 16:54, schrieb Stefan Sch=E4fer: =0A Hi Dani=
ele.=0A>=0A>If your RX is successful enough, maybe a simple transformer wor=
ks well. =0A>=0A>Apply a test signal by using a loop, say 20cm diameter, in=
ductively=0Acoupling to the ferrite. Then use a secondary winding which goe=
s=0Adirectly to the coax of the RX. Use a 50 Ohm resistor or an=0Aoscillosc=
ope with a 50 Ohm input directly. Adjust the number of turns=0Ato get a max=
imum signal voltage on the scope. The match also strongly=0Adepends on the =
position of this secondary winding on the coil. The=0Aimpedance becomes low=
er when you come closer to the center of the rod. =0A>=0A>The will affect t=
he Q of the resonated system. So you may build an=0Aarrangement which allow=
s you to move and fix the secondary coil on the=0Arod. If the signal is str=
ong enough, maybe from a nearby BCD station,=0Ayou can reduce the "gain" a =
bit. I have done it similarly with my=0Aactive ferrite antenna, see https:/=
/dl.dropbox.com/u/19882028/LF/DK7FC_LF_p_active_ferrite_antenna.JPG=0A>=0A>=
73, Stefan/DK7FC=0A>=0A>=0A>Am 28.06.2012 16:14, schrieb Daniele Tincani: =
=0A>Hello LF, =0A>>=0A>>=0A>>it seems I managed to build a pretty good ferr=
ite coil (abot=0A80=0Aturns of Litz wire over a bundle of=A0seven 20cmx1cm =
rods). Nulling and=0Apeaking seem acceptable for my purposes. With current =
var cap, tuning=0Arange is about 160-650 kHz and could=A0easily be moved to=
 lower=0Afrequencies by adding a parallel fixed capacitor. Until now I have=
 only=0Amade some quick tests by inductively coupling the coil with the=0Ai=
nternal ferrite of a portable radio. I would like now to make the antenna s=
uitable also for=0Adirect connection with a 50 ohm input. What do you sugge=
st: to add for=0Aexample a transformer or a buffer amplifier (or both :-))?=
 If a=0Atransformer is recommended, is it advisable to use the main coil as=
 the=0Aprimary winding? =0A>>=0A>>73 =0A>>Daniele IZ5WWB =0A>>         
--671563967-845364515-1340899243=:16908
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<html><body><div style=3D"color:#000; background-color:#fff; font-family:Co=
urier New, courier, monaco, monospace, sans-serif;font-size:10pt"><div><spa=
n>Hello Stefan, your hand-sketched schematics (and also the way you&nbsp;bu=
ilt&nbsp;the antenna,&nbsp;etc.)&nbsp;look just like my idea of the final r=
esult I would like to obtain. BTW I still have some BF862s from my experime=
nts with your VLF E-probe :-) I think I would try to replicate your example=
.</span></div><div><span>73</span></div><div><span>Daniele IZ5WWB</span></d=
iv><div><br></div>  <div style=3D"font-family: Courier New, courier, monaco=
, monospace, sans-serif; font-size: 10pt;"> <div style=3D"font-family: time=
s new roman, new york, times, serif; font-size: 12pt;"> <div dir=3D"ltr"> <=
font size=3D"2" face=3D"Arial"> <div style=3D"margin: 5px 0px; padding: 0px=
; border: 1px solid rgb(204, 204, 204); height: 0px; line-height: 0; font-s=
ize: 0px;" class=3D"hr" contentEditable=3D"false" readonly=3D"true"></div> =
 <b><span
 style=3D"font-weight: bold;">Da:</span></b> Stefan Sch=E4fer &lt;Stefan.Sc=
haefer@iup.uni-heidelberg.de&gt;<br> <b><span style=3D"font-weight: bold;">=
A:</span></b> rsgb_lf_group@blacksheep.org <br> <b><span style=3D"font-weig=
ht: bold;">Inviato:</span></b> Gioved=EC 28 Giugno 2012 17:22<br> <b><span =
style=3D"font-weight: bold;">Oggetto:</span></b> Re: LF: Coupling a LF reso=
nant ferrite rx antenna<br> </font> </div> <br><meta content=3D"off" http-e=
quiv=3D"x-dns-prefetch-control"><div id=3D"yiv2012386837">=0A=0A=0A=0A  =0A=
=0A<div>=0APS: For a 50 Ohm output, just 2 or 3 turns on the out-coupling w=
inding=0Awas the best choice for my ferrite antenna.<br>=0A<br>=0AAm 28.06.=
2012 16:54, schrieb Stefan Sch=E4fer:=0A<blockquote type=3D"cite">=0A=0A  =
=0A  <title></title>=0AHi Daniele.<br>=0A  <br>=0AIf your RX is successful =
enough, maybe a simple transformer works well.=0A  <br>=0A  <br>=0AApply a =
test signal by using a loop, say 20cm diameter, inductively=0Acoupling to t=
he ferrite. Then use a secondary winding which goes=0Adirectly to the coax =
of the RX. Use a 50 Ohm resistor or an=0Aoscilloscope with a 50 Ohm input d=
irectly. Adjust the number of turns=0Ato get a maximum signal voltage on th=
e scope. The match also strongly=0Adepends on the position of this secondar=
y winding on the coil. The=0Aimpedance becomes lower when you come closer t=
o the center of the rod. <br>=0A  <br>=0AThe will affect the Q of the reson=
ated system. So you may build an=0Aarrangement which allows you to move and=
 fix the secondary coil on the=0Arod. If the signal is strong enough, maybe=
 from a nearby BCD station,=0Ayou can reduce the "gain" a bit. I have done =
it similarly with my=0Aactive ferrite antenna, see=0A  <a class=3D"yiv20123=
86837moz-txt-link-freetext" href=3D"https://dl.dropbox.com/u/19882028/LF/DK=
7FC_LF_p_active_ferrite_antenna.JPG" rel=3D"nofollow" target=3D"_blank">htt=
ps://dl.dropbox.com/u/19882028/LF/DK7FC_LF_p_active_ferrite_antenna.JPG</a>=
<br>=0A  <br>=0A73, Stefan/DK7FC<br>=0A  <br>=0A  <br>=0AAm 28.06.2012 16:1=
4, schrieb Daniele Tincani:=0A  <blockquote type=3D"cite">=0A    <div style=
=3D"color: rgb(0, 0, 0); font-family: Courier New, courier, monaco, monospa=
ce, sans-serif; font-size: 10pt; background-color: rgb(255, 255, 255);">=0A=
    <div>Hello LF,</div>=0A    <div style=3D"font-family: Courier New, cour=
ier, monaco, monospace, sans-serif; font-size: 10pt;">=0A    <div style=3D"=
font-family: times new roman, new york, times, serif; font-size: 12pt;">=0A=
    <div id=3D"yiv2012386837">=0A    <div>=0A    <div style=3D"color: rgb(0=
, 0, 0); font-family: Courier New, courier, monaco, monospace, sans-serif; =
font-size: 10pt; background-color: rgb(255, 255, 255);">=0A    <div>&nbsp;<=
/div>=0A    <div>it seems I managed to build a pretty good ferrite coil (ab=
ot=0A80=0Aturns of Litz wire over a bundle of&nbsp;seven 20cmx1cm rods). Nu=
lling and=0Apeaking seem acceptable for my purposes. With current var cap, =
tuning=0Arange is about 160-650 kHz and could&nbsp;easily be moved to lower=
=0Afrequencies by adding a parallel fixed capacitor. Until now I have only=
=0Amade some quick tests by inductively coupling the coil with the=0Aintern=
al ferrite of a portable radio. I would like now to mak<var id=3D"yiv201238=
6837yui-ie-cursor"></var>e the antenna suitable also for=0Adirect connectio=
n with a 50 ohm input. What do you suggest: to add for=0Aexample a transfor=
mer or a buffer amplifier (or both :-))? If a=0Atransformer is recommended,=
 is it advisable to use the main coil as the=0Aprimary winding?</div>=0A   =
 <div>&nbsp;</div>=0A    <div>73</div>=0A    <div>Daniele IZ5WWB</div>=0A  =
  <div>&nbsp;</div>=0A    </div>=0A    </div>=0A    </div>=0A    </div>=0A =
   </div>=0A    </div>=0A  </blockquote>=0A</blockquote>=0A</div>=0A=0A</di=
v><meta content=3D"on" http-equiv=3D"x-dns-prefetch-control"><br><br> </div=
> </div>  </div></body></html>
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