Return-Path: Received: (qmail 31874 invoked from network); 22 Apr 2004 20:05:55 -0000 Received: from unknown (HELO ptb-mxscan03.plus.net) (212.159.14.237) by ptb-mailstore04.plus.net with SMTP; 22 Apr 2004 20:05:55 -0000 Received: (qmail 77394 invoked from network); 22 Apr 2004 20:05:54 -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; 22 Apr 2004 20:05:53 -0000 Received: from post.thorcom.com ([193.82.116.20]) by ptb-mxcore03.plus.net with esmtp (Exim) id 1BGkSH-000K0N-I2 for dave@picks.force9.co.uk; Thu, 22 Apr 2004 21:05:53 +0100 X-Fake-Domain: majordom Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1BGkQg-0006kG-E5 for rs_out_1@blacksheep.org; Thu, 22 Apr 2004 21:04:14 +0100 Received: from [213.232.95.59] (helo=relay.salmark.net) by post.thorcom.com with esmtp (Exim 4.14) id 1BGkQf-0006k7-JW for rsgb_lf_group@blacksheep.org; Thu, 22 Apr 2004 21:04:13 +0100 Received: from postbode02.zonnet.nl ([62.58.50.89]) by relay.salmark.net with esmtp (Exim 4.24) id 1BGkQc-00034Q-LI for rsgb_lf_group@blacksheep.org; Thu, 22 Apr 2004 21:04:10 +0100 Received: (qmail 26274 invoked by uid 10); 22 Apr 2004 20:03:39 -0000 Received: (vexira-qq 26114-D61A8DE5 invoked from network) 22 Apr 2004 22:03:35 +0200 X-Fake-Domain: unknown Received: from unknown (HELO ibm) ([62.59.191.127]) (envelope-sender ) by postbode02.zonnet.nl (qmail-ldap-1.03) with SMTP for < >; 22 Apr 2004 20:03:35 -0000 X-Bad-Message-ID: no DNS (ibm) Message-ID: <001301c428a3$91696400$2102000a@ibm> From: "Dick" To: rsgb_lf_group@blacksheep.org Date: Thu, 22 Apr 2004 21:53:22 +0200 MIME-Version: 1.0 X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 5.00.2615.200 X-MIMEOLE: Produced By Microsoft MimeOLE V5.00.2615.200 X-AntiVirus: checked by Vexira MailArmor (version: 2.0.1.16; VAE: 6.25.0.2; VDF: 6.25.0.26; host: postbode02.zonnet.nl) X-Spam-Score: 1.0 (+) X-Spam-Report: FROM_ENDS_IN_NUMS=0.869,RCVD_IN_SORBS=0.1 Subject: LF: Questions about (G0MRF) 136kHz transmitter Content-Type: text/plain; charset=iso-8859-1; 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=0.9 required=5.0 tests=FROM_ENDS_IN_NUMS 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 all, Finally I got all the important components to get started with G0MRF's transmitter, as published in Radcom Jan-2003. I still have some questions left, and as I don't want to re-invent the wheel, I hope others can answer them. First of all the FET's used. The original design uses 2 times 34NB20 FET's Vds200V/Id 34A, Rds(on) <0,075 Ohm I don't have them, but I can replace them by IRFP260N or IRFP360 The figures for a IRF360 are: 400V/23A Rds 0.2Ohm I'll plan to run the stuff on 50Volt. The IRF360 has an higher Vds but also a litle higher Rds, I wonder if the Rds has an effect on the output power. Second and more important question is about the output transformer. I don't have the original 3C90 core, so I'm planning to use the core of an old computer monitor for this. Did any of you do this before on the G0MRF's design, and if so I would like to know if there was any difference in number of turns used. I guess the amount of power greatly depends on this output transformer, so that makes it to one of the important parts of the project........ Maybe the number of turns might also be dependend in some kind of way to the type of FET's used. 73 Dick, pa4vhf