Return-Path: Received: from post.thorcom.com (post.thorcom.com [195.171.43.25]) by mtain-dd05.r1000.mx.aol.com (Internet Inbound) with ESMTP id 72143380000F0; Fri, 22 Jun 2012 12:35:30 -0400 (EDT) Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1Si6oh-0006qy-Tn for rs_out_1@blacksheep.org; Fri, 22 Jun 2012 17:34:39 +0100 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1Si6oh-0006qp-Gd for rsgb_lf_group@blacksheep.org; Fri, 22 Jun 2012 17:34:39 +0100 Received: from moutng.kundenserver.de ([212.227.126.171]) by relay1.thorcom.net with esmtp (Exim 4.77) (envelope-from ) id 1Si6of-0007uC-6W for rsgb_lf_group@blacksheep.org; Fri, 22 Jun 2012 17:34:38 +0100 Received: from [192.168.2.104] (p4FD17106.dip.t-dialin.net [79.209.113.6]) by mrelayeu.kundenserver.de (node=mrbap3) with ESMTP (Nemesis) id 0MBSfG-1SYmtO1bEs-00AW6E; Fri, 22 Jun 2012 18:34:36 +0200 Message-ID: <4FE49E9C.4000306@legal-medicine.de> Date: Fri, 22 Jun 2012 18:34:36 +0200 From: pws User-Agent: Mozilla/5.0 (X11; U; Linux i686; de; rv:1.9.2.24) Gecko/20111101 SUSE/3.1.16 Thunderbird/3.1.16 MIME-Version: 1.0 To: rsgb_lf_group@blacksheep.org References: <1340350943.68546.YahooMailNeo@web29504.mail.ird.yahoo.com> <1340375757.35583.YahooMailNeo@web29503.mail.ird.yahoo.com> In-Reply-To: <1340375757.35583.YahooMailNeo@web29503.mail.ird.yahoo.com> X-Provags-ID: V02:K0:4KRkOH+/04+kk422gGEqLujLoXJqcTGZPKTvLv24Crv Ez+yar6iHmgX3oa0R7zfJlzgmLaxHpEyiqOkuzMyJP+eaNMAtB iMz6osUMtMbGmTWNftwXbMyDsR4loDnsnpleKZOE0Xt9CP9CrA v3KmCM5YblCJbNvcyM0SwAWZgPFSP/6JicC04yl4RAlN91QhUB j/p9orUj+Q1K+qD7KUIbDLA1IoUbUd+ze5Ue6/vgpS2wOY3zOc XoixuN27MJfkCHdDhxtaqv7M4oJBpdkkUHWzAIuRWNHXs+5ri8 zqJc5RG55f9kxdC9/GFcU95x7wi86oQw0tTqAGUTZUzSapx+Hz 18clCmpBl1lR65OaEQiM= 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: Hi Daniele, You wrote: > ... As for the BD139, I didn't even suspect it could be used in a RF preamp, I tought of it as good for power stages... > Yes, it's the low Rbb what matters. See: http://www.janascard.cz/PDF/Design%20of%20ultra%20low%20noise%20amplifiers.pdf [...] 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 [212.227.126.171 listed in list.dnswl.org] -0.0 SPF_HELO_PASS SPF: HELO matches SPF record X-Scan-Signature: f62c7cf8eeb8e5a327b71719e9bffff1 Subject: Re: LF: RE: Ferrite broadband (LF-MF) antenna? Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit 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: 0:2:434094304:93952408 X-AOL-SCOLL-URL_COUNT: 0 x-aol-sid: 3039ac1d40914fe49ed17800 X-AOL-IP: 195.171.43.25 X-AOL-SPF: domain : blacksheep.org SPF : none Hi Daniele, You wrote: > ... As for the BD139, I didn't even suspect it could be used in a RF preamp, I tought of it as good for power stages... > Yes, it's the low Rbb what matters. See: http://www.janascard.cz/PDF/Design%20of%20ultra%20low%20noise%20amplifiers.pdf And for ferrite loops I would recommend the antenna section of those doctoral thesis available there: www.vhl.tudelft.nl/pelgrum/DissertationPelgrum.tcl I'm running a "counter wound" ferrite loop along with 3 x BC550 in parallel since many years. Another option could be using an instrumentation amplifier with low noise at low input impedance like INA217 (G=100 up to 800 kHz). So you don't need any kind of push-pull amplifier or balancing input transformator. See: http://www.ti.com/lit/ds/symlink/ina217.pdf BTW: even that old low noise version of the video amplifier NE592 works fine. It's called "TL592". Since it's input impedance is not very low using somewhat higher inductance is recommended (~2-5 mH). 73, Peter, df3lp