Return-Path: X-Spam-DCC: paranoid 1290; Body=2 Fuz1=2 Fuz2=2 X-Spam-Checker-Version: SpamAssassin 3.1.3 (2006-06-01) on lipkowski.org X-Spam-Level: X-Spam-Status: No, score=-1.2 required=5.0 tests=BAYES_00,DNS_FROM_AHBL_RHSBL, SUBJ_RE_NUM autolearn=no version=3.1.3 Received: from post.thorcom.com (post.thorcom.com [195.171.43.25]) by paranoid.lipkowski.org (8.13.7/8.13.7) with ESMTP id t9G8YPWg016016 for ; Fri, 16 Oct 2015 10:34:25 +0200 Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1Zn0Q4-0002pF-UR for rs_out_1@blacksheep.org; Fri, 16 Oct 2015 09:31:20 +0100 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1Zn0Q4-0002p6-Ln for rsgb_lf_group@blacksheep.org; Fri, 16 Oct 2015 09:31:20 +0100 Received: from smarthost01b.mail.zen.net.uk ([212.23.1.3]) by relay1.thorcom.net with esmtp (Exim 4.86) (envelope-from ) id 1Zn0P5-0004yU-Bh for rsgb_lf_group@blacksheep.org; Fri, 16 Oct 2015 09:31:19 +0100 Received: from [82.70.254.222] (helo=[192.168.1.64]) by smarthost01b.mail.zen.net.uk with esmtp (Exim 4.80) (envelope-from ) id 1Zn0Oo-0007pD-Px for rsgb_lf_group@blacksheep.org; Fri, 16 Oct 2015 08:30:02 +0000 Date: Fri, 16 Oct 2015 09:30:02 +0100 From: Chris Wilson Organization: Gatesgarth Developments X-Priority: 3 (Normal) Message-ID: <1658039786.20151016093002@chriswilson.tv> To: John Rabson In-Reply-To: References: <1541636554.20151013163425@chriswilson.tv> <43464DACBFAA49C08A73FB93FFF52105@gnat> <603371935.20151014123307@chriswilson.tv> <9E19F2EA072B4AE3A7A112534A29B460@gnat> <323462263.20151015234436@chriswilson.tv> MIME-Version: 1.0 X-Originating-smarthost01b-IP: [82.70.254.222] X-Scan-Signature: a6b6ffaf48fdddf1ed5c25dc4bf03ee1 Subject: Re[2]: LF: Re: Should I be aiming for a better match than this? Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit 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-Scanned-By: MIMEDefang 2.56 on 10.1.3.10 Status: O X-Status: X-Keywords: X-UID: 4401 Hello John, Friday, October 16, 2015 Ah, right, OK John, thanks for that. I may try a galvanically isolated matching transformer. I realised late last night that my wife's complaining of the workshop alarm having gone off seemingly randomly a couple of times, was associated with me transmitting when it went off again. The RCD in the main fuse box tripping a little earlier has now got her wound up about this new facet to my hobby and extremist views such as "you'll burn the house down", and "you'll pay for the freezer contents if it goes off whilst we are away"... are being uttered :) > Hello Chris, > I use the term “isolation” to emphasise the fact that it does > provide galvanic isolation, which an auto-transformer does not. > The transformer here is a ferrite ring type N90AB from Maplin, with > a 5 turn primary winding and a 10 turn secondary. The transmitter is > a 30 W class E design based on the spreadsheet by G3NYK. In this > configuration, with the antenna system presenting 50 ohms, the > amplifier sees the desired load of about 12 ohms. > 73 John F5VLF -- Best regards, Chris mailto:chris@chriswilson.tv