Return-Path: Received: (qmail 19676 invoked from network); 11 May 2004 21:23:14 -0000 Received: from unknown (HELO ptb-mxscan03.plus.net) (212.159.14.237) by ptb-mailstore04.plus.net with SMTP; 11 May 2004 21:23:14 -0000 Received: (qmail 46436 invoked from network); 11 May 2004 21:23:14 -0000 X-Filtered-by: Plusnet (hmail v1.01) X-Spam-detection-level: 11 Received: from ptb-mxcore03.plus.net (212.159.14.217) by ptb-mxscan03.plus.net with SMTP; 11 May 2004 21:23:13 -0000 Received: from post.thorcom.com ([193.82.116.20]) by ptb-mxcore03.plus.net with esmtp (Exim) id 1BNeiW-000Bx5-Te for dave@picks.force9.co.uk; Tue, 11 May 2004 22:23:12 +0100 X-Fake-Domain: majordom Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1BNehO-0003gd-6R for rs_out_1@blacksheep.org; Tue, 11 May 2004 22:22:02 +0100 Received: from [213.232.95.59] (helo=relay.salmark.net) by post.thorcom.com with esmtp (Exim 4.14) id 1BNehN-0003gU-DS for rsgb_lf_group@blacksheep.org; Tue, 11 May 2004 22:22:01 +0100 Received: from smtp.wp.pl ([212.77.101.160]) by relay.salmark.net with esmtp (Exim 4.24) id 1BNlFm-000323-Bv for rsgb_lf_group@blacksheep.org; Wed, 12 May 2004 05:21:58 +0100 Received: (wp-smtpd smtp.wp.pl 25878 invoked from network); 11 May 2004 23:01:21 +0200 Received: from pa136.sulejowek.sdi.tpnet.pl (HELO sp5zcctrx1) (sq5bpm@[217.99.156.136]) (envelope-sender ) by smtp.wp.pl (wp-smtpd) with SMTP for ; 11 May 2004 23:01:21 +0200 X-Bad-Message-ID: no DNS (men.edu.pl) Message-ID: <000f01c4379b$1cc8d980$c510a8c0@men.edu.pl> From: "Marek SQ5BPM" To: rsgb_lf_group@blacksheep.org Date: Tue, 11 May 2004 21:01:15 -0000 MIME-Version: 1.0 X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2800.1106 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1106 X-AntiVirus: skaner antywirusowy poczty Wirtualnej Polski S. A. [wersja 2.0c] X-WP-AntySpam-Rezultat: NIE-SPAM X-Spam-Score: 0.0 (/) X-Spam-Report: autolearn=no, Subject: Re: LF: G0MRF transmitter problems Content-Type: text/plain; charset=windows-1250; format=flowed Content-Transfer-Encoding: 8bit X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on post.thorcom.com 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-PN-SPAMFiltered: yes X-Spam-Rating: 2 Hello Dick and all, > Hello all, > > well I rewound the ouput transformer. > Again I have problems, and when checking the signal on > a spectrum analyzer I found that it is peaking on the second harmonic. > So it transmits the main signal on 272kHz......... > 136kHz is also present at the ouput, but much much weaker. > > It really makes me puzzling. > > Dick, pa4vhf You're lucky to owe a spectrum analyzer! It would have saved me a lot of time in some projects... However, if you have an oscilloscope as well, check the waveform on FETs, should be fairly close to a square wave. Heavy ringing can pull the output waveform almost to zero after the initial peak, thus making the double frequency (at least this happened to me). Check also for possible coupling of the ouput stage with CMOS driver. What helped in my case was a solution by G3YXM (thank you!) : a capacitor around 1nF in series with around 22 ohms resistor, both connected in parallel to the primary winding of the transformer (marked as Z on the schematic here http://www.wireless.org.uk/136bigtx2.gif ). I am still trying to get some motivation for finishing the RX loop... 73! Marek SQ5BPM