Return-Path: Received: from rly-dd05.mx.aol.com (rly-dd05.mail.aol.com [172.19.141.152]) by air-dd01.mail.aol.com (v121.4) with ESMTP id MAILINDD013-b7b47d1c2fa19e; Fri, 07 Mar 2008 17:34:43 -0500 Received: from post.thorcom.com (post.thorcom.com [193.82.116.20]) by rly-dd05.mx.aol.com (v121.4) with ESMTP id MAILRELAYINDD055-b7b47d1c2fa19e; Fri, 07 Mar 2008 17:34:37 -0500 Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1JXl8j-0005uA-AA for rs_out_1@blacksheep.org; Fri, 07 Mar 2008 22:34:09 +0000 Received: from [83.244.159.144] (helo=relay3.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1JXl8i-0005u1-Kk for rsgb_lf_group@blacksheep.org; Fri, 07 Mar 2008 22:34:08 +0000 Received: from iasius.site5.com ([216.118.97.235]) by relay3.thorcom.net with esmtp (Exim 4.63) (envelope-from ) id 1JXl8a-0002GJ-VD for rsgb_lf_group@blacksheep.org; Fri, 07 Mar 2008 22:34:08 +0000 Received: from 62-249-237-217.no-dns-yet.enta.net ([62.249.237.217] helo=daddave) by iasius.site5.com with esmtp (Exim 4.68) (envelope-from ) id 1JXl88-000237-E4 for rsgb_lf_group@blacksheep.org; Fri, 07 Mar 2008 17:33:33 -0500 From: "Michael Probert" To: Date: Fri, 7 Mar 2008 22:37:08 -0000 MIME-Version: 1.0 X-Mailer: Microsoft Office Outlook, Build 11.0.5510 In-Reply-To: <47D1A6FF.1080803@telia.com> X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.3198 Thread-Index: AciAk6jD5g48YWy1RAO6/UWVESTrrQADTdcg X-PopBeforeSMTPSenders: mjprobert@ynysdawelcottages.com{ X-AntiAbuse: This header was added to track abuse, please include it with any abuse report X-AntiAbuse: Primary Hostname - iasius.site5.com X-AntiAbuse: Original Domain - blacksheep.org X-AntiAbuse: Originator/Caller UID/GID - [47 12] / [47 12] X-AntiAbuse: Sender Address Domain - ynysdawelcottages.com X-Source: X-Source-Args: X-Source-Dir: X-Spam-Score: 0.0 (/) X-Spam-Report: autolearn=disabled,none Message-Id: Subject: LF: RE: Smaller DC feeding choke in class E amplifier Content-Type: text/plain; charset="us-ascii" 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 Johan and LF, During my experiments with class E the choke was not a component to which I paid great attention. Having said that, when operating at 500khz, I tried reducing the value to around a few 100uH which resulted in instability. Increased to 4mH at which value the amplifier operated perfectly. That's where I left it and tolerate the very small increase in voltage drop. The amplifier operates at 90% or better efficiency when run at the design values As an aside, I have not blown a fet when running into open circuit or mis tuned antenna. Thanks for the info Johan 73 Mike GW4HXO. ----------------------------------------------------------- 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 __________ NOD32 2930 (20080307) Information __________ This message was checked by NOD32 antivirus system. http://www.eset.com