Return-Path: Received: from mtain-dg09.r1000.mx.aol.com (mtain-dg09.r1000.mx.aol.com [172.29.65.17]) by air-mb07.mail.aol.com (v127_r1.1) with ESMTP id MAILINMB071-a7844bafaa01307; Sun, 28 Mar 2010 15:12:01 -0400 Received: from post.thorcom.com (post.thorcom.com [193.82.116.20]) by mtain-dg09.r1000.mx.aol.com (Internet Inbound) with ESMTP id C1E94380000A3; Sun, 28 Mar 2010 15:11:59 -0400 (EDT) Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1NvxsO-0004va-Qr for rs_out_1@blacksheep.org; Sun, 28 Mar 2010 20:10:24 +0100 Received: from [193.82.116.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1NvxsO-0004vR-Ad for rsgb_lf_group@blacksheep.org; Sun, 28 Mar 2010 20:10:24 +0100 Received: from mail.gmx.net ([213.165.64.20]) by relay1.thorcom.net with smtp (Exim 4.63) (envelope-from ) id 1NvxsL-0001F5-Oe for rsgb_lf_group@blacksheep.org; Sun, 28 Mar 2010 20:10:24 +0100 Received: (qmail invoked by alias); 28 Mar 2010 19:10:15 -0000 Received: from p5DC429E4.dip.t-dialin.net (EHLO Clemens04) [93.196.41.228] by mail.gmx.net (mp010) with SMTP; 28 Mar 2010 21:10:15 +0200 X-Authenticated: #17214767 X-Provags-ID: V01U2FsdGVkX1987RkUovN8eVDP3skdUpqAMdK0dP09D0kQXKcJ1k Z/HoMs3h2v35aE Message-ID: <021b01caceaa$4c358ae0$0201a8c0@Clemens04> From: "Clemens Paul" To: References: <71A8DF2CFC0B4036B2664789F2AC98E0@PCCasa> Date: Sun, 28 Mar 2010 21:10:09 +0200 MIME-Version: 1.0 X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2900.3598 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.3350 X-Y-GMX-Trusted: 0 X-FuHaFi: 0.51000000000000001,0.5 X-Spam-Score: 0.0 (/) X-Spam-Report: autolearn=disabled,HTML_MESSAGE=0.001 Subject: LF: Re: Balun for tuned loop antenna Content-Type: multipart/alternative; boundary="----=_NextPart_000_0217_01CACEBB.0CA33830" 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-sid: 3039ac1d41114bafa9ff7a5b X-AOL-IP: 193.82.116.20 ------=_NextPart_000_0217_01CACEBB.0CA33830 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Hi Daniele, according to your description your magnetic loop has an inductively co= upled secondary coil, the pickup coil as you call it, which presumably performs a step-down= transformation of around 10:1. Therefore -because of the inductive coupling - you can operate unbalanced on the secondary,i.e. rx side ,without dist= urbing the receiving=20 loop's balance itself. As to mismatch losses you need not worry at all. If the rx had 50 Ohm and the antenna output 1000 Ohm you would just lo= ose 7,4dB, with 2500 Ohm it would be 8,3dB. If your rx had say 10 kOhm and the antenna 500Ohm you would loose agai= n 7,4dB. This is of *any* importance for SNR on MW/LW because of the high atms= opheric noise. Probably your low cost RX even will benefit from this small signal att= enuation in terms of less overloading. 73 Clemens DL4RAJ ----- Original Message -----=20 From: Daniele Tincani To: rsgb_lf_group@blacksheep.org Sent: Sunday, March 28, 2010 8:08 PM Subject: LF: Balun for tuned loop antenna Hi all, I'm new to the LF and just starting to play with an homebrew tuned= magloop and my small=20 portable (Tecsun PL-600). I managed to enable (by means of the soldering iron :-)) the externa= l antenna jack also for MF=20 and LF on PL-600 (normally it only works in HF). Now I can connect the= pick-up turn of my=20 magloop directly to the radio but I know it would be better to try to= keep it balanced by means=20 of a balun. Here my problem: magloop simulation (with rjeloop3.exe) te= lls the antenna has an=20 impedance of between 500 and 2500 ohms (on the frequencies it covers,= from 280KHz up to=20 1000KHz). On the other hand, I don't think the receiver have a 50ohm= input. In fact, it is=20 designed typically for HF random wires and has a JFET input buffer sta= ge that should ensure an=20 high impedance. Given these conditions, does it still make sense to bu= ild a balun? If yes, how=20 could it be designed in terms of number of turns (primary side and sec= ondary side), etc.? Many thanks for any feedback. Reg's Daniele ----------------------------------------------------------------------= -------- Eingehende eMail ist virenfrei. Von AVG =FCberpr=FCft - www.avg.de Version: 9.0.791 / Virendatenbank: 271.1.1/2775 - Ausgabedatum: 03/2= 8/10 08:32:00 ------=_NextPart_000_0217_01CACEBB.0CA33830 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
Hi Daniele,
 
according to your description your ma= gnetic loop=20 has an inductively coupled secondary coil,
the pickup coil as you call it,=20 which presumably performs a step-down transformation
of around 10:1.
Therefore -because of the inductive= coupling -=20
you can operate unbalanced on th= e=20 secondary,i.e. rx side ,without disturbing the receiving=20 loop's
balance itself.
As to mismatch losses you need not wo= rry at=20 all.
If the rx had 50 Ohm and the antenna= output 1000=20 Ohm you would just loose 7,4dB= ,
with 2500 Ohm it would be 8,3dB.=
If your rx had say 10 kOhm and the an= tenna 500Ohm=20 you would loose again 7,4dB.
This is of *any* importance for = SNR on MW/LW=20 because of the high atmsopheric noise.
Probably your low cost RX even will= benefit from=20 this small signal attenuation in terms of less
overloading.
 
73
Clemens
DL4RAJ
----- Original Message -----
From:=20 Daniele Tincani
Sent: Sunday, March 28, 2010= 8:08=20 PM
Subject: LF: Balun for tuned= loop=20 antenna

Hi all,
I'm new to the LF and just starting= to play with=20 an homebrew tuned magloop and my small portable (Tecsun PL-600).
I managed to enable (by means of th= e soldering=20 iron :-)) the external antenna jack also for MF and LF on PL-600 (no= rmally it=20 only works in HF). Now I can connect the pick-up turn of my magloop= directly=20 to the radio but I know it would be better to try to keep it balance= d by means=20 of a balun. Here my problem: magloop simulation (with rjeloop3.= exe)=20 tells the antenna has an impedance of between 500 and 2500= ohms (on=20 the frequencies it covers, from 280KHz up to 1000KHz). On the other= hand, I=20 don't think the receiver have a 50ohm input. In fact, it is designed= typically=20 for HF random wires and has a JFET input buffer stage that should en= sure an=20 high impedance. Given these conditions, does it still make sense to= build a=20 balun? If yes, how could it be designed in terms of number of turns= (primary=20 side and secondary side), etc.?
Many thanks for any feedback.
Reg's
Daniele
 


Eingehende eMail ist virenfrei.
Von AVG =FCberpr=FCft= - www.avg.de=20
Version: 9.0.791 / Virendatenbank: 271.1.1/2775 - Ausgabedatum:= 03/28/10=20 08:32:00
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