Return-Path: Received: from rly-mf09.mx.aol.com (rly-mf09.mail.aol.com [172.20.29.179]) by air-mf04.mail.aol.com (v121.4) with ESMTP id MAILINMF041-97e47d1b407128; Fri, 07 Mar 2008 16:30:55 -0500 Received: from post.thorcom.com (post.thorcom.com [193.82.116.20]) by rly-mf09.mx.aol.com (v121.4) with ESMTP id MAILRELAYINMF094-97e47d1b407128; Fri, 07 Mar 2008 16:30:51 -0500 Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1JXk8p-0005gB-5A for rs_out_1@blacksheep.org; Fri, 07 Mar 2008 21:30:11 +0000 Received: from [193.82.59.130] (helo=relay2.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1JXk8o-0005g2-K0 for rsgb_lf_group@blacksheep.org; Fri, 07 Mar 2008 21:30:10 +0000 Received: from smtp811.mail.ird.yahoo.com ([217.146.188.71]) by relay2.thorcom.net with smtp (Exim 4.63) (envelope-from ) id 1JXk8j-0000sV-ND for rsgb_lf_group@blacksheep.org; Fri, 07 Mar 2008 21:30:10 +0000 Received: (qmail 7038 invoked from network); 7 Mar 2008 21:29:55 -0000 DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws; s=s1024; d=btinternet.com; h=Received:X-YMail-OSG:X-Yahoo-Newman-Property:Message-ID:From:To:References:Subject:Date:MIME-Version:Content-Type:Content-Transfer-Encoding:X-Priority:X-MSMail-Priority:X-Mailer:X-MimeOLE; b=E7okg7Zs5Ng0QlDQE686qr89ZY2e6hcgchMPDWpo8qQS2jrRJygicLWUXwMYPHR45PuZlfMI6u7TnxCTUjsaF7Gt/hmrmsxXnXLbbsHnKzEMkwiVBGB78L3s8VGjHmv4P3y3NNEmh5UfPfxxbYB15Kfep34f6HAhAxBtMqlQ/q4= ; Received: from unknown (HELO Lark) (alan.melia@btinternet.com@81.131.7.138 with login) by smtp811.mail.ird.yahoo.com with SMTP; 7 Mar 2008 21:29:55 -0000 X-YMail-OSG: w6er.ScVM1lwz4sVxBxUzRpHvz8ZK1MdT46bQy6Yu27MVD0lt.ps_2Cu60k3eS7ddcG8_znv0a3KtDDK2DS6A6fS9KXVEmB400ieLDbcCrsAQrU5 X-Yahoo-Newman-Property: ymail-3 Message-ID: <00d001c8809a$71f10940$0900a8c0@Lark> From: "Alan Melia" To: References: <47D1A6FF.1080803@telia.com> Date: Fri, 7 Mar 2008 21:26:37 -0000 MIME-Version: 1.0 X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2600.0000 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2600.0000 DomainKey-Status: good (testing) X-Spam-Score: -0.4 (/) X-Spam-Report: autolearn=disabled,AWL=-0.417 Subject: LF: Re: Smaller DC feeding choke in class E amplifier 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 : n X-AOL-SCOLL-AUTHENTICATION: listenair ; SPF_822_from : n Hi Johan, yes a quick look suggests a value of anything over about 120uH would do the job at 136 with a 10ohm load. I looked for data when I started to experiment as I am sure you did and just built a big choke with thick wire in a 50mm FX2240 pot core. It measured out at about 2mH and really "clunked" at switching on. I must read in more detail as at a first scan I did not see the choke resistance in any equation. Most test amps made used at least 500mH I think at 136, though what the effect of the current thought the choke and the field in the ferrite was I havent a clue. I did not look for saturation. Nice Find Thanks Alan G3NYK ----- Original Message ----- From: "Johan H. Bodin" To: Sent: Friday, March 07, 2008 8:35 PM Subject: LF: Smaller DC feeding choke in class E amplifier > LFers, > > the usual design equations for class E amplifiers assume that the DC feeding > choke has a very large inductance in order to keep the DC current practically > constant over the RF cycle. I am in the process of building (yet another) class > E CW QRP transmitter and the need for an almost infinite inductance has annoyed > me for quite a while. Somewhere between the solder smoke puffs, I did some > googling and found this interesting paper: > > http://www.msm.ele.tue.nl/~dmilosev/ECCTD2005.pdf > > My current project is a small 80m TX but I think this information is applicable > to LF as well. > > 73 > Johan SM6LKM >