Return-Path: Received: from rly-me09.mx.aol.com (rly-me09.mail.aol.com [172.20.83.43]) by air-me02.mail.aol.com (v120.9) with ESMTP id MAILINME022-9dc472f014b231; Mon, 05 Nov 2007 06:41:11 -0400 Received: from post.thorcom.com (post.thorcom.com [193.82.116.20]) by rly-me09.mx.aol.com (v120.9) with ESMTP id MAILRELAYINME098-9dc472f014b231; Mon, 05 Nov 2007 06:41:02 -0400 Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1Ip0K8-0005yU-R0 for rs_out_1@blacksheep.org; Mon, 05 Nov 2007 11:40:56 +0000 Received: from [193.82.116.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1Ip0K8-0005yL-EZ for rsgb_lf_group@blacksheep.org; Mon, 05 Nov 2007 11:40:56 +0000 Received: from smtpout0160.sc1.he.tucows.com ([64.97.136.160] helo=n064.sc1.he.tucows.com) by relay1.thorcom.net with esmtp (Exim 4.63) (envelope-from ) id 1Ip0K4-0003rx-Ue for rsgb_lf_group@blacksheep.org; Mon, 05 Nov 2007 11:40:56 +0000 Received: from g3kev (62.252.235.101) by n064.sc1.he.tucows.com (7.2.069.1) id 47030C3D0027F331 for rsgb_lf_group@blacksheep.org; Mon, 5 Nov 2007 11:40:23 +0000 Message-ID: <007201c81fa0$a9154130$65ebfc3e@g3kev> From: "hamilton mal" To: References: <000701c81ede$3af050e0$1ae4fc3e@g3kev> <000701c81ee2$84728900$df2a7ad5@w4o8m9> Date: Mon, 5 Nov 2007 10:36:08 -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: 350: karmasphere.f2kintegrated=350.0 X-Spam-Score: 0.0 (/) X-Spam-Report: autolearn=disabled,none Subject: Re: 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 : ----- Original Message ----- From: "Andy Talbot" To: Sent: Sunday, November 04, 2007 4:57 PM Subject: Re: LF: Re: CLASS D and E > In my 700 Watt direct-from mains transmitter > http://www.scrbg.org/g4jnt/137tx.pdf > efficiency came out somewhere between 80 to 90%. As Jim says, its > difficult to measure accurately At one point, due to measurement > errors, the calculated efficiency ended up at 105%. This is what I mean. Now over 100% eff any advance on this figure!!! > > Andy G4JNT > > > > On 04/11/2007, James Moritz wrote: > > 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 > > > > > > >