Return-Path: Received: (qmail 89870 invoked from network); 24 Nov 2004 21:28:15 -0000 Received: from unknown (HELO ptb-spamcore02.plus.net) (192.168.71.3) by ptb-mailstore02.plus.net with SMTP; 24 Nov 2004 21:28:15 -0000 Received: from mailnull by ptb-spamcore02.plus.net with spamcore-l-b (Exim 4.32; FreeBSD) id 1CX4gj-000Eo4-55 for dave@picks.force9.co.uk; Wed, 24 Nov 2004 21:28:33 +0000 Received: from [192.168.67.2] (helo=ptb-mxcore02.plus.net) by ptb-spamcore02.plus.net with esmtp (Exim 4.32; FreeBSD) id 1CX4gj-000Eo1-2F for dave@picks.force9.co.uk; Wed, 24 Nov 2004 21:28:33 +0000 Received: from post.thorcom.com ([193.82.116.20]) by ptb-mxcore02.plus.net with esmtp (Exim) id 1CX4gL-000K15-IA for dave@picks.force9.co.uk; Wed, 24 Nov 2004 21:28:09 +0000 Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1CX4fn-0003FF-RZ for rs_out_1@blacksheep.org; Wed, 24 Nov 2004 21:27:35 +0000 Received: from [193.82.116.30] (helo=relay.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1CX4fn-0003F6-G2 for rsgb_lf_group@blacksheep.org; Wed, 24 Nov 2004 21:27:35 +0000 Received: from msgdirector2.onetel.net.uk ([212.67.96.149] ident=mirapoint) by relay.thorcom.net with esmtp (Exim 4.41) id 1CX4fj-0005vI-90 for rsgb_lf_group@blacksheep.org; Wed, 24 Nov 2004 21:27:35 +0000 Received: from mail05.onetel.net.uk (mail05.onetel.net.uk [212.67.96.157]) by msgdirector2.onetel.net.uk (MOS 3.4.6-GR) with ESMTP id CCN02882; Wed, 24 Nov 2004 21:26:57 GMT Received: from mail05.onetel.net.uk (localhost.onetel.net.uk [127.0.0.1]) by mail05.onetel.net.uk (MOS 3.4.6-GR) with ESMTP id CDJ25618; Wed, 24 Nov 2004 21:26:56 GMT Received: from 213.78.182.231 by mail05.onetel.net.uk (MOS 3.4.6-GR) with HTTP/1.1; Wed, 24 Nov 2004 21:26:56 GMT Date: Wed, 24 Nov 2004 21:26:56 GMT From: Brian G3YKB To: rsgb_lf_group@blacksheep.org X-Mailer: Webmail Mirapoint Direct 3.4.6-GR MIME-Version: 1.0 Message-Id: X-SPF-Result: relay.thorcom.net: 212.67.96.149 is neither permitted nor denied by domain of onetel.com X-Spam-Score: 0.0 (/) X-Spam-Report: autolearn=no, Subject: Re: LF: Linear amplifiers Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 8bit X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on post.thorcom.com 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-Spam-Filtered: by PlusNet SpamCORE (v3.00) >What circuits do they use? How do they ensure they are >linear? What efficiency do they get?> My amp uses a darlington pair/PNP-NPN complementary arrangement - much like some early audio amplifiers. Only linearity checks I've made are by staring at the waveforms on a scope and asking for IMD on air checks. The amp is basically a bunch of emitter followers so I hope it is inherently linear. The efficiency is pathetic. I would have expected to get at least 60% from a class AB circuit but it is below 40 !! Brian G3YKB