Return-Path: Received: from post.thorcom.com (post.thorcom.com [195.171.43.25]) by mtain-db03.r1000.mx.aol.com (Internet Inbound) with ESMTP id 89BBF3800009A; Fri, 16 Dec 2011 15:21:48 -0500 (EST) Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1RbeGn-00067J-3f for rs_out_1@blacksheep.org; Fri, 16 Dec 2011 20:20:41 +0000 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1RbeGm-00067A-IZ for rsgb_lf_group@blacksheep.org; Fri, 16 Dec 2011 20:20:40 +0000 Received: from mail-iy0-f171.google.com ([209.85.210.171]) by relay1.thorcom.net with esmtp (Exim 4.63) (envelope-from ) id 1RbeGi-0004nx-ON for rsgb_lf_group@blacksheep.org; Fri, 16 Dec 2011 20:20:40 +0000 Received: by iagw33 with SMTP id w33so4997407iag.16 for ; Fri, 16 Dec 2011 12:20:29 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :content-type:content-transfer-encoding; bh=lSVIuxubmJbJlgUF5SQZLapm2ap301qyNb4jYZYnt34=; b=qkSH9hubJyqINo4iaKAlOA6p/Ee4WgxVHax2P/dk/FIudcogI29RM1G0y3fy2rZWtN NtS88wz3IuxChnL4BmdzPHENdwxsf86Kg8TDb48xhBfooF2dr++kWQHoZ/gk8lM1C/1E np37+oqVo6YPWYJsYlcX7kADUU/hA5ciTmh08= MIME-Version: 1.0 Received: by 10.50.183.233 with SMTP id ep9mr10470217igc.67.1324066829443; Fri, 16 Dec 2011 12:20:29 -0800 (PST) Received: by 10.231.66.5 with HTTP; Fri, 16 Dec 2011 12:20:29 -0800 (PST) In-Reply-To: References: <9147461.1324046122200.JavaMail.root@wamui-bucket.atl.sa.earthlink.net> Date: Fri, 16 Dec 2011 20:20:29 +0000 Message-ID: From: Andy Talbot To: rsgb_lf_group@blacksheep.org X-Spam-Score: 0.0 (/) X-Spam-Report: autolearn=disabled,none Subject: Re: LF: RE: Wellbrook Loop Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable 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-global-disposition: G X-AOL-SCOLL-SCORE: 0:2:442407680:93952408 X-AOL-SCOLL-URL_COUNT: 0 X-AOL-SCOLL-AUTHENTICATION: mail_rly_antispam_dkim-m025.1 ; domain : gmail.com DKIM : pass x-aol-sid: 3039ac1d40574eeba85c6e4a X-AOL-IP: 195.171.43.25 X-AOL-SPF: domain : blacksheep.org SPF : none This sort of outline concept for a balanced augmented configuration... http://www.g4jnt.com/LFLoopAnt.gif Not sure if the emitter centre tap needs to be decoupled to actual ground. If not, the whole amp is completely RF floating wrt the ground connection. The input certainly doesn't Andy On 16 December 2011 18:54, Andy Talbot wrote: >> But, looking at the circuit of the preamp in Figure 6, I'm wondering > if, instead of what is virtually two independent input stages, with > their own separate transformers, you considered a differential > push-pull feedback as a single entity. =A0 Have a centre tapped > secondary in the bases (with the centre tap to AC ground), =A0but with > the primary connected between the two emitters, ie directly across the > loop input. > > The two input transistors now operate in true differential mode, > rather than as mostly-independent amplifier stages, and with only one > feedback transformer, complexity and wire losses are reduced. =A0 This > will give even more decoupling of the loop from ground. > > Andy > www.g4jnt.com > >