Return-Path: Received: from mtain-dg06.r1000.mx.aol.com (mtain-dg06.r1000.mx.aol.com [172.29.65.14]) by air-dc08.mail.aol.com (v129.10) with ESMTP id MAILINDC083-86544dcfcb42296; Sun, 15 May 2011 08:46:58 -0400 Received: from post.thorcom.com (post.thorcom.com [195.171.43.25]) by mtain-dg06.r1000.mx.aol.com (Internet Inbound) with ESMTP id 34F6138000186; Sun, 15 May 2011 08:46:56 -0400 (EDT) Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1QLahZ-00086h-Fg for rs_out_1@blacksheep.org; Sun, 15 May 2011 13:45:41 +0100 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1QLahY-00086Y-UM for rsgb_lf_group@blacksheep.org; Sun, 15 May 2011 13:45:40 +0100 Received: from vader.london.02.net ([82.132.130.150] helo=mail.o2.co.uk) by relay1.thorcom.net with esmtp (Exim 4.63) (envelope-from ) id 1QLahW-0004K9-DG for rsgb_lf_group@blacksheep.org; Sun, 15 May 2011 13:45:40 +0100 Received: from [192.168.1.122] (87.194.98.211) by mail.o2.co.uk (8.5.119.05) (authenticated as m0dts@o2.co.uk) id 4DA2BC23058F8FD0 for rsgb_lf_group@blacksheep.org; Sun, 15 May 2011 13:50:34 +0100 Message-ID: <4DCFCAE6.8080407@m0dts.co.uk> Date: Sun, 15 May 2011 13:45:26 +0100 From: "Rob, M0DTS" User-Agent: Mozilla/5.0 (Windows; U; Windows NT 6.1; en-US; rv:1.9.2.13) Gecko/20101207 Thunderbird/3.1.7 MIME-Version: 1.0 To: rsgb_lf_group@blacksheep.org References: <80703.53770.qm@web28515.mail.ukl.yahoo.com> <4DCEDBB3.1020808@iup.uni-heidelberg.de> <4DCFA642.5070305@m0dts.co.uk> In-Reply-To: X-Spam-Score: 1.4 (+) X-Spam-Report: autolearn=disabled,RATWARE_GECKO_BUILD=1.426 Subject: Re: LF: Re: LF SWR Bridge 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: 3039ac1d410e4dcfcb4015b1 X-AOL-IP: 195.171.43.25 X-AOL-SPF: domain : blacksheep.org SPF : none X-Mailer: Unknown (No Version) Aha now I've got it.. Thanks for the tips and it was the winding phase i had incorrect.. obvious now ;-) I will examine at the tuning aids documents too, they look very helpful. Cheers Rob M0DTS On 15/05/2011 12:42, James Moritz wrote: > Dear Rob, LF Group, > > The inductance of the transformer is probably a bit on the low side > (the reactance of the total 24turn winding should be much greater than > the 68R load resistance), but should be enough to get at least > reasonably close to balance - you should be able to see at least some > reduction on the "reflect" side with 50R load connected. Check that > the phasing of the secondary winding is correct - the centre tap > should be the connection between the "start" of one winding and the > "finish" of the other. > > What should happen is the RF voltage on one half of the current > transformer secondary is equal in magnitude, but opposite in phase to > the load voltage sensed by the capacitive voltage divider when the > load is 50R. The component values shown look about right to do this. > One way to check this would be to: > > -Disconnect the "hot" end of the capacitive potential divider from the > TX input terminal. Note the meter readings with the TX running into > 50R load. > -Disable the current transformer by shorting the 24 turn secondary and > re-connect the capacitors .Check the meter deflections with 50R load - > it should be possible to get these the same as in the first test by > adjusting the trimmer capacitor. > > You can find some other ideas about LF antenna tuning aids in the file > LF_Tuning_aids.pdf at > https://sites.google.com/site/uk500khz/members-files/files > > Cheers, Jim Moritz > 73 de M0BMU > > >