Received: from post.thorcom.com (post.thorcom.com [195.171.43.25]) by mtain-de04.r1000.mx.aol.com (Internet Inbound) with ESMTP id A1B013800020A; Thu, 1 Sep 2011 10:00:00 -0400 (EDT) Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1Qz7mu-0000Wf-Ef for rs_out_1@blacksheep.org; Thu, 01 Sep 2011 14:58:36 +0100 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1Qz7mu-0000WQ-1U for rsgb_lf_group@blacksheep.org; Thu, 01 Sep 2011 14:58:36 +0100 Received: from moutng.kundenserver.de ([212.227.17.10]) by relay1.thorcom.net with esmtp (Exim 4.63) (envelope-from ) id 1Qz7ms-0008Jb-Fg for rsgb_lf_group@blacksheep.org; Thu, 01 Sep 2011 14:58:36 +0100 Received: from [192.168.2.102] (p548D59DD.dip.t-dialin.net [84.141.89.221]) by mrelayeu.kundenserver.de (node=mrbap1) with ESMTP (Nemesis) id 0LnDqv-1RQDH72Y4j-00hBb0; Thu, 01 Sep 2011 15:58:28 +0200 Message-ID: <4E5F8F83.7050404@legal-medicine.de> Date: Thu, 01 Sep 2011 15:58:27 +0200 From: pws User-Agent: Mozilla/5.0 (X11; U; Linux i686; de; rv:1.9.2.18) Gecko/20110616 SUSE/3.1.11 Thunderbird/3.1.11 MIME-Version: 1.0 To: rsgb_lf_group@blacksheep.org References: <16BC8B3CA8672445BC2A29B4C14A26D4379ED2AAB4@exlnmb01.eur.nsroot.net> <4DF9EFD1.5010208@iup.uni-heidelberg.de> <1313780109.51443.YahooMailNeo@web111907.mail.gq1.yahoo.com> <9CD1E11E8BC9402CB4AECECAC4088443@JimPC> <1314394178.5030.YahooMailNeo@web111905.mail.gq1.yahoo.com> <1314641183.5605.YahooMailNeo@web111910.mail.gq1.yahoo.com> <4E5CBC9A.5020900@iup.uni-heidelberg.de> <1314705226.37125.YahooMailNeo@web111901.mail.gq1.yahoo.com> <4E5CF192.3040905@legal-medicine.de> <8CA4D9371AE446EDAA7576F42D258CF1@JimPC> In-Reply-To: <8CA4D9371AE446EDAA7576F42D258CF1@JimPC> X-Provags-ID: V02:K0:v7GkWCg66lE0AozAf58ns9crnyICFTUrfCy/2yWraP0 xOr4r51/DlNR0NifZ080QJxL00m6dtgjzMaYPvA0HqihqslnDm 1/0mzuVvL9hRXF7VHu+X6W6vMpEIgG291dPCYGTwDYwDabB3HF d6NfeZhLjHsvHR8xPTWEWtw2uTQvJEUi4pFBZsD2B9JpBhHAGM YpUA0wyliXlRtXxGnbP5aY6MNw5C4ESqxp2sryrzQA7jVshWh8 M/GiLMmA0CWUw2xv4oTCMP4qFT71pclOUEOz9V2W6O9B4U0Id0 N40/EYI0tWaY9aPgTTLbkGDqK7N/ikblt7r6PcuaGCkEO1qyD+ Aedy1C3K4Ei+Q3YOyF6QqNayRMFHZMZvoppJZDY69 X-Spam-Score: 1.4 (+) X-Spam-Report: autolearn=disabled,RATWARE_GECKO_BUILD=1.426 Subject: Re: LF: Re: Ferrite wideband antennas? 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: 0:2:323529728:93952408 X-AOL-SCOLL-URL_COUNT: 0 x-aol-sid: 3039ac1d40cc4e5f8fdf66b4 X-AOL-IP: 195.171.43.25 X-AOL-SPF: domain : blacksheep.org SPF : none Hi Jim, You wrote: > ... > I would be interested to know what method you used to determine SNR for the > different rod configurations. > ... Simply by going the broadband way and using a very low noise, very low impedance pre-amplifier. It's easy to get voltage noises below 1nV/sqrt(Hz) by running some transistors in parallel. Today I know that it's a low "Rbb" of the transistor type what makes the difference. Unfortunately it's hard to find this value in datasheets. I remember using BC327 or BC337 running at ~10mA each. Fortunately current noise doesn't matter here. The antennas had an inductance elsewhere around 0.5 mH. So the self resonances lowered by 200-300pF added by the transistors had been at least 1 octave above the region of interest. Obtaining spectra at a quiet spot will immediately showed the differences of SNRs since some constant signals were available not influenced by the ionosphere e.g. 147 kHz or Loran-C. I had/have such quiet spot here for field-days, a constructor's trailer made of sheet included. This was of importance for shielding the computer. Checking the depths of *both* "nulls" will give some hints about the balance. Peter, df3lp