Return-Path: Received: from rly-me04.mx.aol.com (rly-me04.mail.aol.com [172.20.83.38]) by air-me04.mail.aol.com (v120.9) with ESMTP id MAILINME043-9b4472dc2b04a; Sun, 04 Nov 2007 08:01:53 -0400 Received: from post.thorcom.com (post.thorcom.com [193.82.116.20]) by rly-me04.mx.aol.com (v120.9) with ESMTP id MAILRELAYINME048-9b4472dc2b04a; Sun, 04 Nov 2007 08:01:38 -0400 Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1Iof6Y-0007uI-9v for rs_out_1@blacksheep.org; Sun, 04 Nov 2007 13:01:30 +0000 Received: from [193.82.116.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1Iof6X-0007u8-Rs for rsgb_lf_group@blacksheep.org; Sun, 04 Nov 2007 13:01:29 +0000 Received: from smtp813.mail.ird.yahoo.com ([217.146.188.73]) by relay1.thorcom.net with smtp (Exim 4.63) (envelope-from ) id 1Iof6U-0002km-CB for rsgb_lf_group@blacksheep.org; Sun, 04 Nov 2007 13:01:29 +0000 Received: (qmail 33506 invoked from network); 4 Nov 2007 13:01:00 -0000 DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws; s=s1024; d=btopenworld.com; h=Received:X-YMail-OSG:Received:Message-ID:From:To:References:Subject:Date:MIME-Version:Content-Type:Content-Transfer-Encoding:X-Priority:X-MSMail-Priority:X-Mailer:X-MimeOLE; b=laHDmFAkZwkvCcwCL/K0SwZ6N+Cze19+MUGqf7d1V9hPgIsh7PJqpBY/YGnyucvkEi6K7bxlNLtCYphgpV7+rypVAT7xpI2eBna9++Lan3jRNe2pMoNfuuZ5K7AsH26wU1/UwDzhwaHRyTBS3gifpZZMDrIpkKo5OqwkKFeY+00= ; Received: from unknown (HELO w4o8m9) (james.moritz@btopenworld.com@213.122.42.223 with login) by smtp813.mail.ird.yahoo.com with SMTP; 4 Nov 2007 13:00:59 -0000 X-YMail-OSG: 1B_OHLMVM1lAgzUMW1tgwTGqzf7YMhaE2XmlV74GJlAUE9Eo4rsl0zoMuV.8iF2B8jldw_nBjA-- Received: from 127.0.0.1 (AVG SMTP 7.5.503 [269.15.20/1108]); Sun, 04 Nov 2007 12:59:21 +0000 Message-ID: <000701c81ee2$84728900$df2a7ad5@w4o8m9> From: "James Moritz" To: References: <000701c81ede$3af050e0$1ae4fc3e@g3kev> Date: Sun, 4 Nov 2007 12:59:20 -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-Karma: 0: DomainKey-Status: good (testing) X-Spam-Score: 0.0 (/) X-Spam-Report: autolearn=disabled,none Subject: LF: Re: CLASS D and E Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on post.thorcom.com X-Spam-Level: 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-AOL-IP: 193.82.116.20 X-AOL-SCOLL-AUTHENTICATION: listenair ; SPF_helo : X-AOL-SCOLL-AUTHENTICATION: listenair ; SPF_822_from : Dear Mal, LF Group, > Hi all > Class D and E amplifiers are supposed to give around 80/90 % efficiency. Has > anyone actually achieved these figures. It seems anything above 60% is hard > to arrive at using normal coils/capacitors. > > 73 de Mal/G3KEV > Certainly you should be getting better than 80% for a reasonable class D or E design at LF or MF. I find about 90% is typical for a "good" design - it is actually quite hard to get an accurate figure due to the small difference between DC input and RF output powers. In my designs I have used silver-mica or polypropylene capacitors, which have very low losses at these frequencies. For inductors, I have used air-wound coils and Micrometals -2 mix iron-dust toroid cores - the rule here is if doesen't get excessively hot with the key down, the power loss is probably ok! For most class D and E designs, which have quite low loaded-Q tank circuits (<5, say) an inductor Q of 100 or more is probably adequate and fairly easy to achieve. If you want to use a high loaded-Q tank circuit, it might be another story... Cheers, Jim Moritz 73 de M0BMU