Return-Path: Received: (qmail 42560 invoked from network); 11 Jan 2004 12:22:32 -0000 Received: from unknown (HELO ptb-mxscan01.plus.net) (212.159.14.235) by ptb-mailstore01.plus.net with SMTP; 11 Jan 2004 12:22:32 -0000 Received: (qmail 1662 invoked from network); 11 Jan 2004 12:22:32 -0000 X-Filtered-by: Plusnet (hmail v1.01) X-Priority: 3 X-MSMail-Priority: Normal X-Spam-detection-level: 11 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1106 Received: from ptb-mxcore01.plus.net (212.159.14.215) by ptb-mxscan01.plus.net with SMTP; 11 Jan 2004 12:22:31 -0000 Received: from post.thorcom.com ([193.82.116.20]) by ptb-mxcore01.plus.net with esmtp (Exim) id 1Afebv-0000JY-Kt for dave@picks.force9.co.uk; Sun, 11 Jan 2004 12:22:31 +0000 X-Fake-Domain: majordom Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1Afebd-0004z0-Nd for rs_out@blacksheep.org; Sun, 11 Jan 2004 12:22:13 +0000 Received: from [217.72.192.165] (helo=mailgate5.cinetic.de) by post.thorcom.com with esmtp (Exim 4.14) id 1Afebd-0004yr-64 for rsgb_lf_group@blacksheep.org; Sun, 11 Jan 2004 12:22:13 +0000 Received: from web.de (fmomail03.dlan.cinetic.de [172.20.1.236]) by mailgate5.cinetic.de (8.11.6p2/8.11.2/SuSE Linux 8.11.0-0.4) with SMTP id i0BCLgQ13690 for rsgb_lf_group@blacksheep.org; Sun, 11 Jan 2004 13:21:42 +0100 Date: Sun, 11 Jan 2004 13:21:42 +0100 Message-ID: <200401111221.i0BCLgQ13690@mailgate5.cinetic.de> MIME-Version: 1.0 Organization: http://freemail.web.de/ From: "Hans-Albrecht Haffa" To: rsgb_lf_group@blacksheep.org Subject: Re: LF: 300W-TX-G0MRF Content-Type: text/plain; charset=iso-8859-1; format=flowed Content-Transfer-Encoding: 8bit X-Spam-Checker-Version: SpamAssassin 2.60 (1.212-2003-09-23-exp) on post.thorcom.com X-Spam-Status: No, hits=0.0 required=5.0 tests=none autolearn=no version=2.60 X-SA-Exim-Scanned: Yes Sender: Precedence: bulk Reply-To: rsgb_lf_group@blacksheep.org X-Listname: rsgb_lf_group X-SA-Exim-Rcpt-To: rs_out@blacksheep.org X-SA-Exim-Scanned: No; SAEximRunCond expanded to false X-PN-SPAMFiltered: yes X-Spam-Rating: 1 Dear Peter, I have had similar problems in constructing PAs. First: One reason for the ringing might be the transistors. Put a capacitor 2n7/ 3kV ceramic from drain to source at each PA-transistor. This is likeliy if the pa is operated with an quiescent current. sec.: If You dont have any quiescent current at all, than there is no damping resistor at the transformer for the winding that is not driven . Any winding of a transformer that carries no current will ring. This effect has been never described in amateur radio . The only thing You can do against is adding an quiescent current or using an topology where all windings carry allways a current, that is only two windings, pri and sec. More upon request. Hans-Albrecht Haffa DK 8 ND CBA, ++49-(0)7161 - 87847 rsgb_lf_group@blacksheep.org schrieb am 07.01.04 16:04:23: > > dj9dw schrieb: > > Hello group, > > as I can't get in contact with David, G0MRF, I want to spread out my problem > > here. > > The TX works fine except the outputtransformer T2. There is heavy ringing at > > abt 1 MHz. Now I figured, the inductance seems to be abt 300uH from drain to > > drain. That shure is far too much. > > Could it be that David has changed the toroid - type to one with higher u so > > that 10 turns primary has to be reduced? > > Your help is very welcom, I am stuck. > > > > Regards, dj9dw, Peter. > > Hi Peter, > > pse see > > http://www.qsl.net/dj8wx/My%20second%20transmitter.htm > > if T2 is not pressed p.e. between two ceramic pieces > it should be coold by a fan or else it vibrates on subharmonics of the > transmitted QRG. > > btw. how did you find out a "ringing" at abt 1MHz ? > > best regards > > Uwe/dj8wx > > > > > ______________________________________________________________________________ Nachrichten, Musik und Spiele schnell und einfach per Quickstart im WEB.DE Screensaver - Gratis downloaden: http://screensaver.web.de/?mc=021110