Return-Path: Received: from post.thorcom.com (post.thorcom.com [195.171.43.25]) by mtain-dc06.r1000.mx.aol.com (Internet Inbound) with ESMTP id 2E52C380000F3; Thu, 28 Jun 2012 11:25:57 -0400 (EDT) Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1SkGaN-0006di-Ub for rs_out_1@blacksheep.org; Thu, 28 Jun 2012 16:24:47 +0100 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1SkGaL-0006dZ-Hy for rsgb_lf_group@blacksheep.org; Thu, 28 Jun 2012 16:24:45 +0100 Received: from relay.uni-heidelberg.de ([129.206.100.212]) by relay1.thorcom.net with esmtps (TLSv1:AES256-SHA:256) (Exim 4.77) (envelope-from ) id 1SkGaJ-0003KZ-DR for rsgb_lf_group@blacksheep.org; Thu, 28 Jun 2012 16:24:44 +0100 Received: from freitag.iup.uni-heidelberg.de (freitag.iup.uni-heidelberg.de [129.206.29.204]) by relay.uni-heidelberg.de (8.14.1/8.14.1) with ESMTP id q5SFOgRj009465 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=NO) for ; Thu, 28 Jun 2012 17:24:42 +0200 Received: from [129.206.22.206] (pc206.iup.uni-heidelberg.de [129.206.22.206]) by freitag.iup.uni-heidelberg.de (8.12.11.20060308/8.11.2) with ESMTP id q5SFOg5N001607 for ; Thu, 28 Jun 2012 17:24:42 +0200 Message-ID: <4FEC76C8.9040700@iup.uni-heidelberg.de> Date: Thu, 28 Jun 2012 17:22:48 +0200 From: =?ISO-8859-1?Q?Stefan_Sch=E4fer?= User-Agent: Mozilla/5.0 (Windows; U; Windows NT 6.1; de; rv:1.9.1.8) Gecko/20100227 Thunderbird/3.0.3 MIME-Version: 1.0 To: rsgb_lf_group@blacksheep.org References: <1474092.1340466836144.JavaMail.root@wamui-june.atl.sa.earthlink.net> <1340474829.4474.YahooMailNeo@web29504.mail.ird.yahoo.com> <1340892687.85075.YahooMailNeo@web29503.mail.ird.yahoo.com> <1340892873.80692.YahooMailNeo@web29505.mail.ird.yahoo.com> <4FEC7008.9010001@iup.uni-heidelberg.de> In-Reply-To: <4FEC7008.9010001@iup.uni-heidelberg.de> X-Spam-Score: -0.7 (/) X-Spam-Report: Spam detection software, running on the system "relay1.thorcom.net", has identified this incoming email as possible spam. The original message has been attached to this so you can view it (if it isn't spam) or label similar future email. If you have any questions, see the administrator of that system for details. Content preview: PS: For a 50 Ohm output, just 2 or 3 turns on the out-coupling winding was the best choice for my ferrite antenna. Am 28.06.2012 16:54, schrieb Stefan Schäfer: > Hi Daniele. > > If your RX is successful enough, maybe a simple transformer works well. > > Apply a test signal by using a loop, say 20cm diameter, inductively > coupling to the ferrite. Then use a secondary winding which goes > directly to the coax of the RX. Use a 50 Ohm resistor or an > oscilloscope with a 50 Ohm input directly. Adjust the number of turns > to get a maximum signal voltage on the scope. The match also strongly > depends on the position of this secondary winding on the coil. The > impedance becomes lower when you come closer to the center of the rod. > > The will affect the Q of the resonated system. So you may build an > arrangement which allows you to move and fix the secondary coil on the > rod. If the signal is strong enough, maybe from a nearby BCD station, > you can reduce the "gain" a bit. I have done it similarly with my > active ferrite antenna, see > https://dl.dropbox.com/u/19882028/LF/DK7FC_LF_p_active_ferrite_antenna.JPG > > 73, Stefan/DK7FC > > > Am 28.06.2012 16:14, schrieb Daniele Tincani: >> Hello LF, >> it seems I managed to build a pretty good ferrite coil (abot 80 turns >> of Litz wire over a bundle of seven 20cmx1cm rods). Nulling and >> peaking seem acceptable for my purposes. With current var cap, tuning >> range is about 160-650 kHz and could easily be moved to lower >> frequencies by adding a parallel fixed capacitor. Until now I have >> only made some quick tests by inductively coupling the coil with the >> internal ferrite of a portable radio. I would like now to make the >> antenna suitable also for direct connection with a 50 ohm input. What >> do you suggest: to add for example a transformer or a buffer >> amplifier (or both :-))? If a transformer is recommended, is it >> advisable to use the main coil as the primary winding? >> 73 >> Daniele IZ5WWB [...] Content analysis details: (-0.7 points, 5.0 required) pts rule name description ---- ---------------------- -------------------------------------------------- -0.7 RCVD_IN_DNSWL_LOW RBL: Sender listed at http://www.dnswl.org/, low trust [129.206.100.212 listed in list.dnswl.org] -0.0 T_RP_MATCHES_RCVD Envelope sender domain matches handover relay domain 0.0 HTML_MESSAGE BODY: HTML included in message X-Scan-Signature: 9be3f060697a097db7a337109fbeece1 Subject: Re: LF: Coupling a LF resonant ferrite rx antenna Content-Type: multipart/alternative; boundary="------------040304070206080106030807" X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on post.thorcom.com X-Spam-Level: X-Spam-Status: No, hits=0.5 required=5.0 tests=HTML_20_30,HTML_MESSAGE autolearn=no version=2.63 X-SA-Exim-Scanned: Yes Sender: owner-rsgb_lf_group@blacksheep.org Precedence: bulk Reply-To: rsgb_lf_group@blacksheep.org X-Listname: rsgb_lf_group X-SA-Exim-Rcpt-To: rs_out_1@blacksheep.org X-SA-Exim-Scanned: No; SAEximRunCond expanded to false x-aol-global-disposition: G X-AOL-SCOLL-SCORE: 0:2:409444960:93952408 X-AOL-SCOLL-URL_COUNT: 0 x-aol-sid: 3039ac1d40864fec778547c2 X-AOL-IP: 195.171.43.25 X-AOL-SPF: domain : blacksheep.org SPF : none This is a multi-part message in MIME format. --------------040304070206080106030807 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: quoted-printable X-MIME-Autoconverted: from 8bit to quoted-printable by relay.uni-heidelberg.de id q5SFOgRj009465 PS: For a 50 Ohm output, just 2 or 3 turns on the out-coupling winding=20 was the best choice for my ferrite antenna. Am 28.06.2012 16:54, schrieb Stefan Sch=E4fer: > Hi Daniele. > > If your RX is successful enough, maybe a simple transformer works well. > > Apply a test signal by using a loop, say 20cm diameter, inductively=20 > coupling to the ferrite. Then use a secondary winding which goes=20 > directly to the coax of the RX. Use a 50 Ohm resistor or an=20 > oscilloscope with a 50 Ohm input directly. Adjust the number of turns=20 > to get a maximum signal voltage on the scope. The match also strongly=20 > depends on the position of this secondary winding on the coil. The=20 > impedance becomes lower when you come closer to the center of the rod. > > The will affect the Q of the resonated system. So you may build an=20 > arrangement which allows you to move and fix the secondary coil on the=20 > rod. If the signal is strong enough, maybe from a nearby BCD station,=20 > you can reduce the "gain" a bit. I have done it similarly with my=20 > active ferrite antenna, see=20 > https://dl.dropbox.com/u/19882028/LF/DK7FC_LF_p_active_ferrite_antenna.= JPG > > 73, Stefan/DK7FC > > > Am 28.06.2012 16:14, schrieb Daniele Tincani: >> Hello LF, >> it seems I managed to build a pretty good ferrite coil (abot 80 turns=20 >> of Litz wire over a bundle of seven 20cmx1cm rods). Nulling and=20 >> peaking seem acceptable for my purposes. With current var cap, tuning=20 >> range is about 160-650 kHz and could easily be moved to lower=20 >> frequencies by adding a parallel fixed capacitor. Until now I have=20 >> only made some quick tests by inductively coupling the coil with the=20 >> internal ferrite of a portable radio. I would like now to make the=20 >> antenna suitable also for direct connection with a 50 ohm input. What=20 >> do you suggest: to add for example a transformer or a buffer=20 >> amplifier (or both :-))? If a transformer is recommended, is it=20 >> advisable to use the main coil as the primary winding? >> 73 >> Daniele IZ5WWB --------------040304070206080106030807 Content-Type: text/html; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit PS: For a 50 Ohm output, just 2 or 3 turns on the out-coupling winding was the best choice for my ferrite antenna.

Am 28.06.2012 16:54, schrieb Stefan Schäfer:
Hi Daniele.

If your RX is successful enough, maybe a simple transformer works well.

Apply a test signal by using a loop, say 20cm diameter, inductively coupling to the ferrite. Then use a secondary winding which goes directly to the coax of the RX. Use a 50 Ohm resistor or an oscilloscope with a 50 Ohm input directly. Adjust the number of turns to get a maximum signal voltage on the scope. The match also strongly depends on the position of this secondary winding on the coil. The impedance becomes lower when you come closer to the center of the rod.

The will affect the Q of the resonated system. So you may build an arrangement which allows you to move and fix the secondary coil on the rod. If the signal is strong enough, maybe from a nearby BCD station, you can reduce the "gain" a bit. I have done it similarly with my active ferrite antenna, see https://dl.dropbox.com/u/19882028/LF/DK7FC_LF_p_active_ferrite_antenna.JPG

73, Stefan/DK7FC


Am 28.06.2012 16:14, schrieb Daniele Tincani:
Hello LF,
 
it seems I managed to build a pretty good ferrite coil (abot 80 turns of Litz wire over a bundle of seven 20cmx1cm rods). Nulling and peaking seem acceptable for my purposes. With current var cap, tuning range is about 160-650 kHz and could easily be moved to lower frequencies by adding a parallel fixed capacitor. Until now I have only made some quick tests by inductively coupling the coil with the internal ferrite of a portable radio. I would like now to make the antenna suitable also for direct connection with a 50 ohm input. What do you suggest: to add for example a transformer or a buffer amplifier (or both :-))? If a transformer is recommended, is it advisable to use the main coil as the primary winding?
 
73
Daniele IZ5WWB
 
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