Return-Path: Received: from post.thorcom.com (post.thorcom.com [195.171.43.25]) by mtain-dl06.r1000.mx.aol.com (Internet Inbound) with ESMTP id 1AC42380000AA; Mon, 16 Jul 2012 21:45:12 -0400 (EDT) Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1SquqN-0004PL-00 for rs_out_1@blacksheep.org; Tue, 17 Jul 2012 00:36:47 +0100 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1SquqM-0004PC-DP for rsgb_lf_group@blacksheep.org; Tue, 17 Jul 2012 00:36:46 +0100 Received: from relay.uni-heidelberg.de ([129.206.100.212]) by relay1.thorcom.net with esmtps (TLSv1:AES256-SHA:256) (Exim 4.77) (envelope-from ) id 1SquqK-0007sU-SU for rsgb_lf_group@blacksheep.org; Tue, 17 Jul 2012 00:36:45 +0100 Received: from freitag.iup.uni-heidelberg.de (freitag.iup.uni-heidelberg.de [129.206.29.204]) by relay.uni-heidelberg.de (8.14.1/8.14.1) with ESMTP id q6GNahta019213 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=NO) for ; Tue, 17 Jul 2012 01:36:44 +0200 Received: from [129.206.22.206] (pc206.iup.uni-heidelberg.de [129.206.22.206]) by freitag.iup.uni-heidelberg.de (8.12.11.20060308/8.11.2) with ESMTP id q6GNahFP022093 for ; Tue, 17 Jul 2012 01:36:43 +0200 Message-ID: <5004A507.7050508@iup.uni-heidelberg.de> Date: Tue, 17 Jul 2012 01:34:31 +0200 From: =?ISO-8859-15?Q?Stefan_Sch=E4fer?= User-Agent: Mozilla/5.0 (Windows; U; Windows NT 6.1; de; rv:1.9.1.8) Gecko/20100227 Thunderbird/3.0.3 MIME-Version: 1.0 To: rsgb_lf_group@blacksheep.org X-Spam-Score: -0.7 (/) 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: MF, Today i've build a box for matching different antenna impedances to the 50 Ohm output of my PA. An amperemeter is inserted in the coax output, so the antenna current can be measured directly, in certain antenna configurations. The circuit is of course nothing special, just a switch with many steps and a transformer with many taps :-) The amperemeter is analog, class 1.5 (made in England, about 40 years old) and i like the rapid moving of the needle (could be a bit slower though, will add some C...). [...] Content analysis details: (-0.7 points, 5.0 required) pts rule name description ---- ---------------------- -------------------------------------------------- -0.7 RCVD_IN_DNSWL_LOW RBL: Sender listed at http://www.dnswl.org/, low trust [129.206.100.212 listed in list.dnswl.org] -0.0 T_RP_MATCHES_RCVD Envelope sender domain matches handover relay domain X-Scan-Signature: 2e2f7cbbe9f38dd7bf3fac4fc012e6fc Subject: LF: MF antenna measurements Content-Type: text/plain; charset=ISO-8859-15; 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: 0:2:408498336:93952408 X-AOL-SCOLL-URL_COUNT: 0 x-aol-sid: 3039ac1d4ad45004c3a83362 X-AOL-IP: 195.171.43.25 X-AOL-SPF: domain : blacksheep.org SPF : none MF, Today i've build a box for matching different antenna impedances to the 50 Ohm output of my PA. An amperemeter is inserted in the coax output, so the antenna current can be measured directly, in certain antenna configurations. The circuit is of course nothing special, just a switch with many steps and a transformer with many taps :-) The amperemeter is analog, class 1.5 (made in England, about 40 years old) and i like the rapid moving of the needle (could be a bit slower though, will add some C...). Now it was possible to accurately measure the resonance of my antenna system using a fixed coil, it is actually 475.5 kHz, exactly the middle of the band. However the Q is very high, the antenna current drops by 3 dB at 472.25 kHz and 478.25 kHz, i.e. the -3 dB BW is 6 kHz and so the (loaded) Q is 79. Thus i think i will need some kind of reactance compensation and intend to use a series configuration of a L and a C, also added by a stepped switch... The impedance switch will allow to match the full size dipole when beeing /p. I will do this test in the coming days. 73 and funny MF times. Stefan/DK7FC