Return-Path: <owner-rsgb_lf_group@blacksheep.org> Received: (qmail 22315 invoked from network); 29 Apr 2003 14:53:12 -0000 Content-Transfer-Encoding: 8bit Received: from warrior.services.quay.plus.net (212.159.14.227) by mailstore with SMTP; 29 Apr 2003 14:53:12 -0000 X-Priority: 3 X-MSMail-Priority: Normal Received: (qmail 24165 invoked from network); 29 Apr 2003 14:53:15 -0000 Received: from post.thorcom.com (193.82.116.70) by warrior.services.quay.plus.net with SMTP; 29 Apr 2003 14:53:15 -0000 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1106 X-SQ: A Received: from majordom by post.thorcom.com with local (Exim 4.14) id 19AWTL-00069m-MO for rsgb_lf_group-outgoing@blacksheep.org; Tue, 29 Apr 2003 15:52:43 +0100 Received: from [212.227.126.188] (helo=moutng.kundenserver.de) by post.thorcom.com with esmtp (Exim 4.14) id 19AWTG-00069d-QJ for rsgb_lf_group@blacksheep.org; Tue, 29 Apr 2003 15:52:38 +0100 Received: from [212.227.126.160] (helo=mrelayng.kundenserver.de) by moutng.kundenserver.de with esmtp (Exim 3.35 #1) id 19AWTG-0007h4-00 for rsgb_lf_group@blacksheep.org; Tue, 29 Apr 2003 16:52:38 +0200 Received: from [80.130.83.78] (helo=FABIAN.diolog.de) by mrelayng.kundenserver.de with asmtp (TLSv1:DES-CBC3-SHA:168) (Exim 3.35 #1) id 19AWT9-0004Dx-00 for rsgb_lf_group@blacksheep.org; Tue, 29 Apr 2003 16:52:35 +0200 Message-ID: <5.2.0.9.0.20030429145028.01d507b0@pop.1und1.com> X-Sender: pt8152986-6@pop.1und1.com X-Mailer: QUALCOMM Windows Eudora Version 5.2.0.9 Date: Tue, 29 Apr 2003 14:51:20 +0100 To: rsgb_lf_group@blacksheep.org From: "Fabian Kurz" <fk@diolog.de> In-reply-to: <5.1.0.14.0.20030429145925.00ae4c60@gemini.herts.ac.uk> MIME-Version: 1.0 Subject: Re: LF: LF Tuning meter Content-Type: text/plain; charset=us-ascii; format=flowed X-Spam-Status: No, hits=-9.8 required=5.0tests=EMAIL_ATTRIBUTION,IN_REP_TOversion=2.53 X-Spam-Checker-Version: SpamAssassin 2.53 (1.174.2.15-2003-03-30-exp) 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: rsgb_lf_group-outgoing@blacksheep.org X-SA-Exim-Scanned: No; SAEximRunCond expanded to false At 15:36 29.04.2003 +0100, you wrote: >Dear LF Group, > >For tuning LF antennas, I have for some time been using an oscilloscope to >monitor the current and voltage waveforms at the TX output. Resonance >occurs when V and I are in phase, and the load resistance is 50ohms when >V/I = 50. This is very easy to use provided a scope is to hand, but not >very useful if it isn't. An SWR bridge can be used, but it only indicates >the degree of mismatch, so tuning is still a matter of trial and error. So >with a mind towards future /P operations, I have built a self-contained >tuning meter. > >The prototype has 2 meters - one indicates phase, while the other can be >switched between voltage and current to determine the load resistance. The >circuit is slightly more complex than an SWR bridge, but not by very much >- it uses 12 diodes, 3 toroid cores and a few other passive components. It >does not require an external power supply, and is usable with TX power >between about 20W and 1.8kW. I have written a 3 page article about it - it >is a pdf file of about 190k, so too big for the reflector, but I can >e-mail it as an attachment to those who are interested. If someone would >like to put it on their web site, they would be more than welcome! I'd appreciate a copy of the pdf-File! 73, Fabian DJ1YFK (currently upgrading the PA some 10dB, so a normal CW QSO is certainly possible soon ;) >Cheers, Jim Moritz >73 de M0BMU >