Return-Path: Received: from post.thorcom.com (post.thorcom.com [195.171.43.25]) by mtain-dl05.r1000.mx.aol.com (Internet Inbound) with ESMTP id 13111380000A7; Thu, 28 Jun 2012 10:30:16 -0400 (EDT) Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1SkFih-0006Js-O8 for rs_out_1@blacksheep.org; Thu, 28 Jun 2012 15:29:19 +0100 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1SkFih-0006Jh-2a for rsgb_lf_group@blacksheep.org; Thu, 28 Jun 2012 15:29:19 +0100 Received: from elasmtp-galgo.atl.sa.earthlink.net ([209.86.89.61]) by relay1.thorcom.net with esmtp (Exim 4.77) (envelope-from ) id 1SkFiY-0002mk-Ar for rsgb_lf_group@blacksheep.org; Thu, 28 Jun 2012 15:29:17 +0100 DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws; s=dk20050327; d=earthlink.net; b=Jypzi2EUumUg9x+MuCFGnsEIpW+iMeGSXGVbMibHBXXLP76XDPpE9gCpdJcFgCY5; h=Message-ID:Date:From:Reply-To:To:Subject:Mime-Version:Content-Type:Content-Transfer-Encoding:X-Mailer:X-ELNK-Trace:X-Originating-IP; Received: from [209.86.224.68] (helo=wamui-hunyo.atl.sa.earthlink.net) by elasmtp-galgo.atl.sa.earthlink.net with esmtpa (Exim 4.67) (envelope-from ) id 1SkFiC-0003sO-4a; Thu, 28 Jun 2012 10:28:48 -0400 Received: from 97.117.196.160 by webmail.c.earthlink.net with HTTP; Thu, 28 Jun 2012 10:28:47 -0400 Message-ID: <9632772.1340893727946.JavaMail.root@wamui-hunyo.atl.sa.earthlink.net> Date: Thu, 28 Jun 2012 07:28:47 -0700 (GMT-07:00) From: Chris Trask To: rsgb_lf_group@blacksheep.org, "rsgb_lf_group@blacksheep.org" Mime-Version: 1.0 X-Mailer: EarthLink Zoo Mail 1.0 X-ELNK-Trace: b77fdb70683249914713efb067f9a722239a348a220c2609aa86267d27a100d00c3863e78b47d2fca2d4e88014a4647c350badd9bab72f9c350badd9bab72f9c X-Originating-IP: 209.86.224.68 X-Spam-Score: -0.0 (/) 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: > > 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? > [...] Content analysis details: (-0.0 points, 5.0 required) pts rule name description ---- ---------------------- -------------------------------------------------- -0.0 RCVD_IN_DNSWL_NONE RBL: Sender listed at http://www.dnswl.org/, no trust [209.86.89.61 listed in list.dnswl.org] -0.0 T_RP_MATCHES_RCVD Envelope sender domain matches handover relay domain X-Scan-Signature: e09cca6d8e44a91eadbdfb3e1b8aec09 Subject: Re: LF: Coupling a LF resonant ferrite rx antenna Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on post.thorcom.com X-Spam-Level: X-Spam-Status: No, hits=0.0 required=5.0 tests=none 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: 0:2:360579168:93952408 X-AOL-SCOLL-URL_COUNT: 0 x-aol-sid: 3039ac1d4ad34fec6a78707f X-AOL-IP: 195.171.43.25 X-AOL-SPF: domain : blacksheep.org SPF : none > > it seems I managed to build a pretty good ferrite coil (abot 80 > turns of Litz wire over a bundle of=C2=A0seven 20cmx1cm rods). > Nulling and peaking seem acceptable for my purposes. With current > var cap, tuning range is about 160-650 kHz and could=C2=A0easily 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? > You may want to look at how I approached this in an active ferrite rod= antenna that I designed some time ago: http://www.home.earthlink.net/~christrask/Paper006.html Chris Trask N7ZWY / WDX3HLB Senior Member IEEE http://www.home.earthlink.net/~christrask/