Return-Path: Received: from mtain-dc04.r1000.mx.aol.com (mtain-dc04.r1000.mx.aol.com [172.29.64.132]) by air-da07.mail.aol.com (v129.4) with ESMTP id MAILINDA074-86674be97f1812a; Tue, 11 May 2010 12:00:24 -0400 Received: from post.thorcom.com (post.thorcom.com [193.82.116.20]) by mtain-dc04.r1000.mx.aol.com (Internet Inbound) with ESMTP id B365F3800008C; Tue, 11 May 2010 12:00:20 -0400 (EDT) Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1OBrqj-0003uI-6g for rs_out_1@blacksheep.org; Tue, 11 May 2010 16:58:25 +0100 Received: from [193.82.59.130] (helo=relay2.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1OBrqg-0003sJ-7d for rsgb_lf_group@blacksheep.org; Tue, 11 May 2010 16:58:22 +0100 Received: from moutng.kundenserver.de ([212.227.17.10]) by relay2.thorcom.net with esmtp (Exim 4.63) (envelope-from ) id 1OBrqc-0005ji-NA for rsgb_lf_group@blacksheep.org; Tue, 11 May 2010 16:58:22 +0100 Received: from [192.168.1.64] (188-221-89-85.zone12.bethere.co.uk [188.221.89.85]) by mrelayeu.kundenserver.de (node=mreu1) with ESMTP (Nemesis) id 0Lb6lR-1NRUU91kCH-00l2nJ; Tue, 11 May 2010 17:58:12 +0200 From: "Dave Sergeant" To: rsgb_lf_group@blacksheep.org Date: Tue, 11 May 2010 16:58:11 +0100 MIME-Version: 1.0 Message-ID: <4BE97E93.12009.23FC007@dave.davesergeant.com> In-reply-to: References: , <28093526.109907.1273582377168.JavaMail.fmail@mwmweb078>, X-mailer: Pegasus Mail for Windows (4.52) Content-description: Mail message body X-Provags-ID: V01U2FsdGVkX18S+wNS/LubiV6i6ws49/nW0I7mx2JblG2r2+a +bybjHkunMoEyfhRL9GCAfgZCeeXUkNC/i0pDiO2N4/S3wMqmN DHDWvyNaCp8rJ3e8bMLUghDPImLXR5f X-Spam-Score: 0.0 (/) X-Spam-Report: autolearn=disabled,none Subject: LF: Re: Sub-9kHz walkabout tests 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-sid: 3039ac1d40844be97f143422 X-AOL-IP: 193.82.116.20 On 11 May 2010 at 15:55, Roger Lapthorn wrote: > There are several sources in the UK for toroidal mains transformers with > various step-down ratios. See for example > http://www.airlinktransformers.com/toroidal-transformers.asp . These > sell for =A312 to =A320 for ratings up to 160VA. They are available up= to > at least 1kVA, but get expensive. >=20 Not sure that mains transformers are appropriate for 9kHz. Probably=20 better would be switch mode psu transformers (normally operate 25kHz- 75kHz) and you could probably design what you wanted with readily=20 available cores (toroid and other). 73 Dave G3YMC http://www.davesergeant.com