Received: from post.thorcom.com (post.thorcom.com [195.171.43.25]) by mtain-da01.r1000.mx.aol.com (Internet Inbound) with ESMTP id 780AA380000A4; Mon, 5 Sep 2011 16:50:49 -0400 (EDT) Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1R0g6f-0004FD-02 for rs_out_1@blacksheep.org; Mon, 05 Sep 2011 21:49:25 +0100 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1R0g6e-0004F4-8w for rsgb_lf_group@blacksheep.org; Mon, 05 Sep 2011 21:49:24 +0100 Received: from nm8.bullet.mail.ird.yahoo.com ([77.238.189.23]) by relay1.thorcom.net with smtp (Exim 4.63) (envelope-from ) id 1R0g6d-0008B8-GD for rsgb_lf_group@blacksheep.org; Mon, 05 Sep 2011 21:49:24 +0100 Received: from [77.238.189.55] by nm8.bullet.mail.ird.yahoo.com with NNFMP; 05 Sep 2011 20:49:15 -0000 Received: from [212.82.108.112] by tm8.bullet.mail.ird.yahoo.com with NNFMP; 05 Sep 2011 20:49:15 -0000 Received: from [127.0.0.1] by omp1021.mail.ird.yahoo.com with NNFMP; 05 Sep 2011 20:49:15 -0000 X-Yahoo-Newman-Property: ymail-3 X-Yahoo-Newman-Id: 47483.29262.bm@omp1021.mail.ird.yahoo.com Received: (qmail 22075 invoked by uid 60001); 5 Sep 2011 20:49:15 -0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=yahoo.com; s=s1024; t=1315255754; bh=xdK02RXyvCisWrMpIZddk9LzzGXVoIVLZfXsYxDdfJw=; h=X-YMail-OSG:Received:X-Mailer:References:Message-ID:Date:From:Reply-To:Subject:To:MIME-Version:Content-Type; b=UbIQyArwIfSd9HsR7xDUd+06xU6/5GyfwM8uE9WyKEodU/7EoGCsJz0jOJajCQZFfKjkFNhqhHCx1fmlA/5HX+iMvjQYdCCR6N1vKncYA6EM421ufC+a6lF/woZTaCqYTj25BXtsKv+q6EWn1/fF3TwiPvGo8uptrtMtkhqH1Yk= DomainKey-Signature:a=rsa-sha1; q=dns; c=nofws; s=s1024; d=yahoo.com; h=X-YMail-OSG:Received:X-Mailer:References:Message-ID:Date:From:Reply-To:Subject:To:MIME-Version:Content-Type; b=YZCvrWFHLDQweb3nZt32MUyBDBMUz2iYgW1T+HnHUx360DW6E3lVjcBwFsfFEwY/Pr2bBElWOa9H8jHHczV6fhkQgUc4HI3eU+TdrN9Z6IOzEvkq6bK9tYFF50E2y6bY3qluFX2OyaYfKUxUC9193AJ795Ifbuq8bcPvVJ6BLIY=; X-YMail-OSG: 26DxN50VM1mP4IWhaPTLtAWY2lbs38LhpvaB0fWaFa1RpiY wlCm5oYuhfYBT4hntjS1Qh_vc_a8uMMCyNMLp2YD68EKaox1R_b4agRw7TtS FNr4nTf6hHUIfb.3XFGTn2gfcH63ImynnXWg5N_j7XUEK_iMSAu8B2Csxlcp H_H1Z9vu_9tS7gFCN5eaLJEW42sF2CDxE_5rfwQJDdv1C.W0_3tOOSkMx5NM MTbW7Jn5eAYQrvIwZuFQV1tCdqlWrhoE0kFhYNLXFjoxp4whLXguX.tW4wK. Wsfa.J1gA2CtVwrH_AR7CQii3NC0G2hbWcEe2Oia1symKopmaYJv8xliX_a9 Wdy9FiUV2BJXMXlmD Received: from [87.3.23.169] by web29501.mail.ird.yahoo.com via HTTP; Mon, 05 Sep 2011 21:49:14 BST X-Mailer: YahooMailWebService/0.8.113.315625 References: <4E64BEB6.7000002@iup.uni-heidelberg.de> <1315225979.12868.YahooMailNeo@web111901.mail.gq1.yahoo.com> <07BFB60B5E834C13864621EBED0D4D51@JimPC> Message-ID: <1315255754.22040.YahooMailNeo@web29501.mail.ird.yahoo.com> Date: Mon, 5 Sep 2011 21:49:14 +0100 (BST) From: Daniele Tincani To: "rsgb_lf_group@blacksheep.org" MIME-Version: 1.0 DomainKey-Status: good (testing) X-Spam-Score: 1.4 (+) X-Spam-Report: autolearn=disabled,HTML_MESSAGE=0.001,HTML_TINY_FONT=1.425 Subject: Re: LF: Loop vs. ferrite antenna tests... Content-Type: multipart/alternative; boundary="-67346210-370953510-1315255754=:22040" X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on post.thorcom.com X-Spam-Level: * X-Spam-Status: No, hits=1.3 required=5.0 tests=FORGED_YAHOO_RCVD,HTML_30_40, HTML_MESSAGE,TO_ADDRESS_EQ_REAL 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: 0:2:468786176:93952408 X-AOL-SCOLL-URL_COUNT: 0 X-AOL-SCOLL-AUTHENTICATION: mail_rly_antispam_dkim-d001.2 ; domain : yahoo.com DKIM : fail x-aol-sid: 3039ac1d40494e6536282837 X-AOL-IP: 195.171.43.25 X-AOL-SPF: domain : blacksheep.org SPF : none ---67346210-370953510-1315255754=:22040 Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: quoted-printable Hello Jim,=0A=A0=0Athank you very much for your help.=0A=A0=0AAlso thanks t= o Stefan and Piotr for their replies and suggestions.=0A=A0=0ABest regards= =0ADaniele=0A=0ADa: James Moritz =0AA: rsgb_l= f_group@blacksheep.org=0AInviato: Luned=EC 5 Settembre 2011 21:21=0AOggetto= : Re: LF: Loop vs. ferrite antenna tests...=0A=0ADear Daniele, LF Group,=0A= =0AThe high-impedance buffer type of loop preamp as I used with my ferrite = rod is probably the best choice for your experiments - it has a number of a= dvantages:=0A=0ALow noise - for loops that have an equivalent parallel resi= stance at resonance of a few kilohms or more, the noise added by the FET bu= ffer is negligible (noise figure <1dB). Almost any practical values of ferr= ite rod L and C will meet this criterion.=0A=0AHigh gain - the output from = the circuit is=0A nearly equal to the EMF induced in the loop multiplied by= the Q of the loop, which will typically mean 40 - 50dB voltage gain. This = increases the rather small induced signal to a level that most reasonably s= ensitive receivers can hear.=0A=0AGood linearity - the unity-gain buffer ha= s inherently large negative feedback, and strong-signal handling is good.= =0A=0ASimplicity - a small number of cheap components, instability is unlik= ely.=0A=0AIf you use this type of circuit (and you have a reasonably sensit= ive receiver), simply connecing the input to the terminals of the resonant = loop will almost guarantee that you will be able to detect any signal that = is above the thermal noise of the loop (and above the external noise level = of course), without having to do detailed design of the preamp or matching = arrangements. So it is good for playing with different designs of loops and= rods.=0A=0AThe main drawback is that the antenna bandwidth is defined by t= he=0A loop Q, and can be very narrow. But if your loop is to be tunable any= way, this does not matter much, and the narrow bandwidth will help prevent = receiver overloading.=0A=0ACheers, Jim Moritz=0A73 de M0BMU ---67346210-370953510-1315255754=:22040 Content-Type: text/html; charset=iso-8859-1 Content-Transfer-Encoding: quoted-printable
Hello Jim,
 
thank you very much for your help.
 
Also thanks to Stefan and= Piotr for their replies and suggestions.
&nb= sp;
Best regards
Daniele

Da: James Moritz <james.moritz@btopenworld.com>
A: rsgb_lf_group@blacksheep.org<= br>Inviato: Luned=EC 5 Set= tembre 2011 21:21
Oggetto:<= /b> Re: LF: Loop vs. ferrite antenna tests...

Dear Daniele, L= F Group,

The high-impedance buffer type of loop preamp as I used with my ferrite rod is= probably the best choice for your experiments - it has a number of advanta= ges:

Low noise - for loops that have an equivalent parallel resistan= ce at resonance of a few kilohms or more, the noise added by the FET buffer= is negligible (noise figure <1dB). Almost any practical values of ferri= te rod L and C will meet this criterion.

High gain - the output from= the circuit is=0A nearly equal to the EMF induced in the loop multiplied b= y the Q of the loop, which will typically mean 40 - 50dB voltage gain. This= increases the rather small induced signal to a level that most reasonably = sensitive receivers can hear.

Good linearity - the unity-gain buffer= has inherently large negative feedback, and strong-signal handling is good= .

Simplicity - a small number of cheap components, instability is un= likely.

If you use this type of circuit (and you have a reasonably s= ensitive receiver), simply connecing the input to the terminals of the reso= nant loop will almost guarantee that you will be able to detect any signal = that is above the thermal noise of the loop (and above the external noise l= evel of course), without having to do detailed design of the preamp or matc= hing arrangements. So it is good for playing with different designs of loop= s and rods.

The main drawback is that the antenna bandwidth is defin= ed by the=0A loop Q, and can be very narrow. But if your loop is to be tuna= ble anyway, this does not matter much, and the narrow bandwidth will help p= revent receiver overloading.

Cheers, Jim Moritz
73 de M0BMU



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