Return-Path: Received: (qmail 70413 invoked from network); 3 Feb 2004 18:47:20 -0000 Received: from unknown (HELO ptb-mxscan02.plus.net) (212.159.14.236) by ptb-mailstore04.plus.net with SMTP; 3 Feb 2004 18:47:20 -0000 Received: (qmail 22141 invoked from network); 3 Feb 2004 18:47:20 -0000 X-Filtered-by: Plusnet (hmail v1.01) X-Spam-detection-level: 11 Received: from ptb-mxcore02.plus.net (212.159.14.216) by ptb-mxscan02.plus.net with SMTP; 3 Feb 2004 18:47:13 -0000 Received: from post.thorcom.com ([193.82.116.20]) by ptb-mxcore02.plus.net with esmtp (Exim) id 1Ao5Zp-0005HH-JY for dave@picks.force9.co.uk; Tue, 03 Feb 2004 18:47:13 +0000 X-Fake-Domain: majordom Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1Ao5Yi-0000nr-U3 for rs_out@blacksheep.org; Tue, 03 Feb 2004 18:46:04 +0000 Received: from [147.197.200.9] (helo=hestia.herts.ac.uk) by post.thorcom.com with esmtp (Exim 4.14) id 1Ao5Yh-0000nh-H3 for rsgb_lf_group@blacksheep.org; Tue, 03 Feb 2004 18:46:03 +0000 X-Fake-Domain: gemini Received: from gemini ([147.197.200.44] helo=gemini.herts.ac.uk) by hestia.herts.ac.uk with esmtp (Exim 3.22 #1) id 1Ao5Tw-0003qG-00 for rsgb_lf_group@blacksheep.org; Tue, 03 Feb 2004 18:41:08 +0000 X-No-DNS-For: 147.197.232.252 Received: from [147.197.232.252] (helo=rsch15) by gemini.herts.ac.uk with esmtp (Exim 3.33 #1) id 1Ao5Tv-00050S-00 for rsgb_lf_group@blacksheep.org; Tue, 03 Feb 2004 18:41:07 +0000 From: "James Moritz" To: rsgb_lf_group@blacksheep.org Date: Tue, 3 Feb 2004 18:41:09 -0000 Organization: University of Hertfordshire X-Bad-Message-ID: no DNS (rsch15) Message-ID: <000001c3ea85$4a539f10$fce8c593@rsch15> MIME-Version: 1.0 X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook, Build 10.0.2627 Importance: Normal In-reply-to: <008801c3ea2f$8a0a5000$062465d5@oemcomputer> X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1106 X-UH-MailScanner: No Virus detected Subject: LF: RE: Re: Schematics powersupplies 50-100Volt wanted Content-Type: text/plain; charset=us-ascii; 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: 2 Dear Dick, LF Group, > I want to run something with an fixed voltage between 50 to 100 Volt, > depending on what transformer configuration I'm using. One of the nice features of class D or other switching-mode amplifiers is that they work much the same when the supply voltage is reduced, except that the output power is also reduced. This means you can test your PA (or tune up the antenna)with a 12V or less current-limited supply and a few watts output, when there is very little chance of damaging components. Then when you are happy all is working OK, connect a higher supply voltage for QRO operation (however, the driver should always be run from its normal supply voltage to ensure proper switching operation of the output devices). It is quite possible to make voltage- and current regulated supplies for QRO transmitters, but they are usually more complicated and expensive than the TX they are supplying power to. Cheers, Jim Moritz 73 de M0BMU