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Message-ID: <51DA0212.8020808@iup.uni-heidelberg.de>
Date: Mon, 08 Jul 2013 02:04:34 +0200
From: =?UTF-8?B?U3RlZmFuIFNjaMOkZmVy?= <Stefan.Schaefer@iup.uni-heidelberg.de>
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Subject: LF: Re: MiniWhip antenna, fiber optic
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another image of the TX:=20
https://dl.dropboxusercontent.com/u/19882028/LF/DK7FC_fiber%20optic%20act=
ive%20dipole_TX2.jpg

Am 08.07.2013 01:59, schrieb Stefan Sch=C3=A4fer:
> Hi all,
>
> OK, although it can't work (do you remember?!) i built an active=20
> antenna with battery supply and fiber optic output. The active part is=20
> a BF862=20
> <https://dl.dropboxusercontent.com/u/19882028/Datenbl%C3%A4tter/BF862.p=
df>.=20
> The circuit is quite simple:=20
> https://dl.dropboxusercontent.com/u/19882028/LF/DK7FC_fiber%20optic%20a=
ctive%20dipole%20schematic.jpg=20
> It is a first idea for the schematic. Maybe i will change it later so=20
> that the gate is shifted to 9V/2. Just for first experiments. In=20
> various tests with the BF862 i found that it was necessary to add a=20
> ferrite bead directly in front of the gate to prevent VHF oscillations=20
> of the JFET.
>
> The TX is already working:=20
> https://dl.dropboxusercontent.com/u/19882028/LF/DK7FC_fiber%20optic%20a=
ctive%20dipole_TX.jpg
> Yes yes yes, it is not truely symmetric and the capacity at source=20
> must be a bit larger than that of the leg connected to gate. Anyway it=20
> will be useful for some basic and interesting experiments.
>
> RX is ready tomorrow.
>
> 73, Stefan/DK7FC

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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
  <meta content=3D"text/html; charset=3DUTF-8" http-equiv=3D"Content-Type=
">
</head>
<body bgcolor=3D"#ffffff" text=3D"#000000">
another image of the TX:
<a class=3D"moz-txt-link-freetext" href=3D"https://dl.dropboxusercontent.=
com/u/19882028/LF/DK7FC_fiber%20optic%20active%20dipole_TX2.jpg">https://=
dl.dropboxusercontent.com/u/19882028/LF/DK7FC_fiber%20optic%20active%20di=
pole_TX2.jpg</a><br>
<br>
Am 08.07.2013 01:59, schrieb Stefan Sch=C3=A4fer:
<blockquote cite=3D"mid:51DA00C8.6000600@iup.uni-heidelberg.de"
 type=3D"cite">
  <meta content=3D"text/html; charset=3DUTF-8" http-equiv=3D"Content-Type=
">
Hi all, <br>
  <br>
OK, although it can't work (do you remember?!) i built an active
antenna with battery supply and fiber optic output. The active part is
a <a moz-do-not-send=3D"true"
 href=3D"https://dl.dropboxusercontent.com/u/19882028/Datenbl%C3%A4tter/B=
F862.pdf">BF862</a>.
The
circuit is quite simple:
  <a moz-do-not-send=3D"true" class=3D"moz-txt-link-freetext"
 href=3D"https://dl.dropboxusercontent.com/u/19882028/LF/DK7FC_fiber%20op=
tic%20active%20dipole%20schematic.jpg">https://dl.dropboxusercontent.com/=
u/19882028/LF/DK7FC_fiber%20optic%20active%20dipole%20schematic.jpg</a>
It is a first idea for the schematic. Maybe i will change it later so
that the gate is shifted to 9V/2. Just for first experiments. In
various tests with the BF862 i found that it was necessary to add a
ferrite bead directly in front of the gate to prevent VHF oscillations
of the JFET.<br>
  <br>
The TX is already working:
  <a moz-do-not-send=3D"true" class=3D"moz-txt-link-freetext"
 href=3D"https://dl.dropboxusercontent.com/u/19882028/LF/DK7FC_fiber%20op=
tic%20active%20dipole_TX.jpg">https://dl.dropboxusercontent.com/u/1988202=
8/LF/DK7FC_fiber%20optic%20active%20dipole_TX.jpg</a><br>
Yes yes yes, it is not truely symmetric and the capacity at source must
be a bit larger than that of the leg connected to gate. Anyway it will
be useful for some basic and interesting experiments. <br>
  <br>
RX is ready tomorrow. <br>
  <br>
73, Stefan/DK7FC</blockquote>
</body>
</html>

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