Return-Path: Received: from mtain-dg03.r1000.mx.aol.com (mtain-dg03.r1000.mx.aol.com [172.29.65.11]) by air-mc03.mail.aol.com (v129.4) with ESMTP id MAILINMC033-a8dd4d8761aa17b; Mon, 21 Mar 2011 10:33:14 -0400 Received: from post.thorcom.com (post.thorcom.com [195.171.43.25]) by mtain-dg03.r1000.mx.aol.com (Internet Inbound) with ESMTP id 1FA52380000D4; Mon, 21 Mar 2011 10:33:12 -0400 (EDT) Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1Q1g9f-0004Xv-RM for rs_out_1@blacksheep.org; Mon, 21 Mar 2011 14:32:23 +0000 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1Q1g9f-0004Xm-Fc for rsgb_lf_group@blacksheep.org; Mon, 21 Mar 2011 14:32:23 +0000 Received: from relay00.pair.com ([209.68.5.9]) by relay1.thorcom.net with smtp (Exim 4.63) (envelope-from ) id 1Q1g9d-0005Sa-Jx for rsgb_lf_group@blacksheep.org; Mon, 21 Mar 2011 14:32:23 +0000 Received: (qmail 52800 invoked from network); 21 Mar 2011 14:32:18 -0000 Received: from 74.94.151.157 (HELO ?192.168.1.56?) (74.94.151.157) by relay00.pair.com with SMTP; 21 Mar 2011 14:32:18 -0000 X-pair-Authenticated: 74.94.151.157 Message-ID: <4D8763CB.4060009@charter.net> Date: Mon, 21 Mar 2011 10:42:19 -0400 From: John Andrews User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.9.2.15) Gecko/20110303 Thunderbird/3.1.9 MIME-Version: 1.0 To: rsgb_lf_group@blacksheep.org References: <4D83D475.9090609@telus.net><000b01cbe622$6a23f8d0$8d01a8c0@JAYDELL>, ,<4D86BD6F.8020006@telus.net> <004101cbe7c1$5171ada0$4001a8c0@lark> <4D874AEC.7000204@charter.net> <004d01cbe7d2$203d0750$4001a8c0@lark> In-Reply-To: <004d01cbe7d2$203d0750$4001a8c0@lark> X-Spam-Score: 1.4 (+) X-Spam-Report: autolearn=disabled,RATWARE_GECKO_BUILD=1.426 Subject: Re: LF: Loop TX antennas at VLF? Content-Type: text/plain; charset=ISO-8859-1; format=flowed 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-global-disposition: G x-aol-sid: 3039ac1d410b4d8761a83919 X-AOL-IP: 195.171.43.25 X-AOL-SPF: domain : blacksheep.org SPF : none X-Mailer: Unknown (No Version) Alan, Yes, you could split the series cap -- assuming that the values were close, the balance would be excellent. Given an audio amp with a bridged output configuration, and the matching network set up for 10-12 Ohms or so, you'd be all set. As Steve points out, variable caps are a problem at 9 kHz, and you'd be compounding it a bit by trying to keep the symmetry. But if you use a transformer to couple to a coax or other line, you can use any tuning/matching setup, and the balance to ground will be OK. John, W1TAG On 3/21/2011 10:13 AM, Alan Melia wrote: > Hi John that is a good point, balanced is always better . I had wondered > whether the cap in series with the loop could be split into two parts to > retain the balance. The article is in the blue backed "Source book" and is > called High Power Matching at VLF by G3OKA ..........split C1 into two parts > ?? This was originally intended for driving a73kHz loop from an 8ohm audio > amp.