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Message-ID: <1373275039.3815.YahooMailNeo@web133201.mail.ir2.yahoo.com>
Date: Mon, 8 Jul 2013 10:17:19 +0100 (BST)
From: M0FMT <m0fmt@yahoo.co.uk>
To: "rsgb_lf_group@blacksheep.org" <rsgb_lf_group@blacksheep.org>
In-Reply-To: <51DA1680.6030602@iup.uni-heidelberg.de>
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Subject: Re: LF: Re: MiniWhip antenna, fiber optic
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--1982344905-1924800410-1373275039=:3815
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Hi Stefan and Joe.=0AJust to say your publishing the results of the tests a=
nd ideas is very interesting to me and I guess to just about the whole MF/L=
F/VLF community.=0A=A0=0AThinking out side the "Box" is important and you a=
re certainly doing that. Please keep us informed.=0A=0A73 es GL Pete M0FMT =
IO91UX=0A=0A=A0=0A=0A>________________________________=0A> From: Stefan Sch=
=E4fer <Stefan.Schaefer@iup.uni-heidelberg.de>=0A>To: rsgb_lf_group@blacksh=
eep.org =0A>Sent: Monday, 8 July 2013, 2:31=0A>Subject: Re: LF: Re: MiniWhi=
p antenna, fiber optic=0A>  =0A>=0A>=0A>Hi all, =0A>=0A>Well, somehow i did=
n't want to stop, so i now built the RX too: https://dl.dropboxusercontent.=
com/u/19882028/LF/DK7FC_fiber%20optic%20active%20dipole_RX.jpg I made some =
changes in the RX schematic, using a J310 instead of the=0ABF862 but the pr=
inciple schematic is the same. The working points look=0Aas expected. BTW t=
hat electrical/optic/electrical converter must be=0Aquite wide in the trans=
ferred frequency range, i guess starting from a=0Afew 100 Hz to a few 100 k=
Hz.=0A>=0A>When connecting the BNC output to the scope, the noise shown fro=
m the=0Ascope does not change. When switching on the active probe there is =
some=0Anoise visible in the range of 2 ms/div. The probe stands in the lab=
=0Awhere many noise sources can be expected. =0A>=0A>And suddenly!!! : It w=
as 1:06 UTC. I am transmitting WSPR-2 each 6=0Aminutes on 630m, from the sa=
me building, in some 10m distance. Suddenly=0Athere was a 472 kHz signal on=
 the scope, although the antenna can't=0Awork :-) The short dipole is compl=
etely floating. See another photo=0Awhere the floating antenna is placed on=
 a (isolating and low coupling=0Acapacity to sourroundings) cardboard: http=
s://dl.dropboxusercontent.com/u/19882028/LF/Signal%21.jpg=0A>=0A>When switc=
hing off the active antenna, the signal disappears completely=0Aon the scop=
e, of course!=0A>=0A>When coming closer with my hand to one of the legs of =
the dipole or the=0Abattery, the signal rises, as expected. I think we can =
agree that this=0Aantenna IS floating!!=0A>=0A>So far for now. It's 3:26 AM=
 and i think i should take some sleep :-)=0ALooking forward to the tomorrow=
s experiments. Let me know if you have=0Asuggestions for experiments!=0A>=
=0A>73, GN, Stefan/DK7FC=0A>=0A>=0A>Am 08.07.2013 02:11, schrieb Stefan Sch=
=E4fer: =0A>3rd: https://dl.dropboxusercontent.com/u/19882028/LF/DK7FC_fibe=
r%20optic%20active%20dipole_TX3.jpg=0A>>=0A>>The optic cable is 9m long.=0A=
>>=0A>>Am 08.07.2013 02:04, schrieb Stefan Sch=E4fer: =0A>>another image of=
 the TX: https://dl.dropboxusercontent.com/u/19882028/LF/DK7FC_fiber%20opti=
c%20active%20dipole_TX2.jpg=0A>>>=0A>>>Am 08.07.2013 01:59, schrieb Stefan =
Sch=E4fer: =0A>>>Hi all, =0A>>>>=0A>>>>OK, although it can't work (do you r=
emember?!) i built an active=0Aantenna with battery supply and fiber optic =
output. The active part is=0Aa BF862.=0AThe=0Acircuit=0Ais=0Aquite simple: =
https://dl.dropboxusercontent.com/u/19882028/LF/DK7FC_fiber%20optic%20activ=
e%20dipole%20schematic.jpg It is a first idea for the schematic. Maybe i wi=
ll change it later so=0Athat the gate is shifted to 9V/2. Just for first ex=
periments. In=0Avarious tests with the BF862 i found that it was necessary =
to add a=0Aferrite bead directly in front of the gate to prevent VHF oscill=
ations=0Aof the JFET.=0A>>>>=0A>>>>The TX is already working: https://dl.dr=
opboxusercontent.com/u/19882028/LF/DK7FC_fiber%20optic%20active%20dipole_TX=
.jpg=0A>>>>Yes yes yes, it is not truely symmetric and the capacity at sour=
ce must=0Abe a bit larger than that of the leg connected to gate. Anyway it=
 will=0Abe useful for some basic and interesting experiments. =0A>>>>=0A>>>=
>RX is ready tomorrow. =0A>>>>=0A>>>>73, Stefan/DK7FC    =0A>=0A>    
--1982344905-1924800410-1373275039=:3815
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<html><body><div style=3D"color:#000; background-color:#fff; font-family:ar=
ial, helvetica, sans-serif;font-size:14pt"><span><div><span>Hi Stefan and J=
oe.</span></div><div><span>Just to say your publishing the results of the t=
ests and ideas is very interesting to me and I guess to just about the whol=
e MF/LF/VLF community.</span></div><div><span></span>&nbsp;</div><div><span=
>Thinking out side the "Box" is important and you are certainly doing that.=
 Please keep us informed.</span><br></div><div>73 es GL Pete M0FMT IO91UX</=
div></span><div><br>&nbsp;</div><div><blockquote style=3D"padding-left: 5px=
; margin-top: 5px; margin-left: 5px; border-left-color: rgb(16, 16, 255); b=
order-left-width: 2px; border-left-style: solid;">  <div style=3D"font-fami=
ly: arial, helvetica, sans-serif; font-size: 14pt;"> <div style=3D"font-fam=
ily: times new roman, new york, times, serif; font-size: 12pt;"> <div dir=
=3D"ltr"> <div class=3D"hr" style=3D"margin: 5px 0px; padding: 0px; border:=
 1px
 solid rgb(204, 204, 204); height: 0px; line-height: 0; font-size: 0px;" co=
ntenteditable=3D"false" readonly=3D"true"></div>  <font face=3D"Arial" size=
=3D"2"> <b><span style=3D"font-weight: bold;">From:</span></b> Stefan Sch=
=E4fer &lt;Stefan.Schaefer@iup.uni-heidelberg.de&gt;<br> <b><span style=3D"=
font-weight: bold;">To:</span></b> rsgb_lf_group@blacksheep.org <br> <b><sp=
an style=3D"font-weight: bold;">Sent:</span></b> Monday, 8 July 2013, 2:31<=
br> <b><span style=3D"font-weight: bold;">Subject:</span></b> Re: LF: Re: M=
iniWhip antenna, fiber optic<br> </font> </div> <div class=3D"y_msg_contain=
er"><var id=3D"yui-ie-cursor"></var><br><div id=3D"yiv2980112099">=0A=0A=0A=
  =0A=0A<div>=0AHi all, <br>=0A<br>=0AWell, somehow i didn't want to stop, =
so i now built the RX too:=0A<a class=3D"yiv2980112099moz-txt-link-freetext=
" href=3D"https://dl.dropboxusercontent.com/u/19882028/LF/DK7FC_fiber%20opt=
ic%20active%20dipole_RX.jpg" target=3D"_blank" rel=3D"nofollow">https://dl.=
dropboxusercontent.com/u/19882028/LF/DK7FC_fiber%20optic%20active%20dipole_=
RX.jpg</a>=0AI made some changes in the RX schematic, using a J310 instead =
of the=0ABF862 but the principle schematic is the same. The working points =
look=0Aas expected. BTW that electrical/optic/electrical converter must be=
=0Aquite wide in the transferred frequency range, i guess starting from a=
=0Afew 100 Hz to a few 100 kHz.<br>=0A<br>=0AWhen connecting the BNC output=
 to the scope, the noise shown from the=0Ascope does not change. When switc=
hing on the active probe there is some=0Anoise visible in the range of 2 ms=
/div. The probe stands in the lab=0Awhere many noise sources can be expecte=
d. <br>=0A<br>=0AAnd suddenly!!! : It was 1:06 UTC. I am transmitting WSPR-=
2 each 6=0Aminutes on 630m, from the same building, in some 10m distance. <=
b>Suddenly=0Athere was a 472 kHz signal on the scope</b>, although the ante=
nna can't=0Awork :-) The short dipole is completely floating. See another p=
hoto=0Awhere the floating antenna is placed on a (isolating and low couplin=
g=0Acapacity to sourroundings) cardboard:=0A<a class=3D"yiv2980112099moz-tx=
t-link-freetext" href=3D"https://dl.dropboxusercontent.com/u/19882028/LF/Si=
gnal%21.jpg" target=3D"_blank" rel=3D"nofollow">https://dl.dropboxuserconte=
nt.com/u/19882028/LF/Signal%21.jpg</a><br>=0A<br>=0AWhen switching off the =
active antenna, the signal disappears completely=0Aon the scope, of course!=
<br>=0A<br>=0AWhen coming closer with my hand to one of the legs of the dip=
ole or the=0Abattery, the signal rises, as expected. I think we can agree t=
hat this=0Aantenna IS floating!!<br>=0A<br>=0ASo far for now. It's 3:26 AM =
and i think i should take some sleep :-)=0ALooking forward to the tomorrows=
 experiments. Let me know if you have=0Asuggestions for experiments!<br>=0A=
<br>=0A73, GN, Stefan/DK7FC<br>=0A<br>=0A<br>=0AAm 08.07.2013 02:11, schrie=
b Stefan Sch=E4fer:=0A<blockquote type=3D"cite">=0A  =0A3rd:=0A  <a class=
=3D"yiv2980112099moz-txt-link-freetext" href=3D"https://dl.dropboxuserconte=
nt.com/u/19882028/LF/DK7FC_fiber%20optic%20active%20dipole_TX3.jpg" target=
=3D"_blank" rel=3D"nofollow">https://dl.dropboxusercontent.com/u/19882028/L=
F/DK7FC_fiber%20optic%20active%20dipole_TX3.jpg</a><br>=0A  <br>=0AThe opti=
c cable is 9m long.<br>=0A  <br>=0AAm 08.07.2013 02:04, schrieb Stefan Sch=
=E4fer:=0A  <blockquote type=3D"cite">=0A    =0Aanother image of the TX: <a=
 class=3D"yiv2980112099moz-txt-link-freetext" href=3D"https://dl.dropboxuse=
rcontent.com/u/19882028/LF/DK7FC_fiber%20optic%20active%20dipole_TX2.jpg" t=
arget=3D"_blank" rel=3D"nofollow">https://dl.dropboxusercontent.com/u/19882=
028/LF/DK7FC_fiber%20optic%20active%20dipole_TX2.jpg</a><br>=0A    <br>=0AA=
m 08.07.2013 01:59, schrieb Stefan Sch=E4fer:=0A    <blockquote type=3D"cit=
e">=0A      =0AHi all, <br>=0A      <br>=0AOK, although it can't work (do y=
ou remember?!) i built an active=0Aantenna with battery supply and fiber op=
tic output. The active part is=0Aa <a href=3D"https://dl.dropboxusercontent=
.com/u/19882028/Datenbl%C3%A4tter/BF862.pdf" target=3D"_blank" rel=3D"nofol=
low">BF862</a>.=0AThe=0Acircuit=0Ais=0Aquite simple: <a class=3D"yiv2980112=
099moz-txt-link-freetext" href=3D"https://dl.dropboxusercontent.com/u/19882=
028/LF/DK7FC_fiber%20optic%20active%20dipole%20schematic.jpg" target=3D"_bl=
ank" rel=3D"nofollow">https://dl.dropboxusercontent.com/u/19882028/LF/DK7FC=
_fiber%20optic%20active%20dipole%20schematic.jpg</a>=0AIt is a first idea f=
or the schematic. Maybe i will change it later so=0Athat the gate is shifte=
d to 9V/2. Just for first experiments. In=0Avarious tests with the BF862 i =
found that it was necessary to add a=0Aferrite bead directly in front of th=
e gate to prevent VHF oscillations=0Aof the JFET.<br>=0A      <br>=0AThe TX=
 is already working: <a class=3D"yiv2980112099moz-txt-link-freetext" href=
=3D"https://dl.dropboxusercontent.com/u/19882028/LF/DK7FC_fiber%20optic%20a=
ctive%20dipole_TX.jpg" target=3D"_blank" rel=3D"nofollow">https://dl.dropbo=
xusercontent.com/u/19882028/LF/DK7FC_fiber%20optic%20active%20dipole_TX.jpg=
</a><br>=0AYes yes yes, it is not truely symmetric and the capacity at sour=
ce must=0Abe a bit larger than that of the leg connected to gate. Anyway it=
 will=0Abe useful for some basic and interesting experiments. <br>=0A      =
<br>=0ARX is ready tomorrow. <br>=0A      <br>=0A73, Stefan/DK7FC</blockquo=
te>=0A  </blockquote>=0A</blockquote>=0A</div>=0A</div><br><br></div> </div=
> </div> </blockquote>  </div></div></body></html>
--1982344905-1924800410-1373275039=:3815--