Return-Path: Received: (qmail 11640 invoked from network); 1 Apr 2005 09:09:44 -0000 Received: from unknown (HELO ptb-spamcore03.plus.net) (192.168.71.7) by ptb-mailstore04.plus.net with SMTP; 1 Apr 2005 09:09:44 -0000 Received: from Debian-exim by ptb-spamcore03.plus.net with spam-scanned (Exim 4.44) id 1DHI9U-0001BK-31 for dave@picks.force9.co.uk; Fri, 01 Apr 2005 10:09:16 +0100 Received: from [192.168.67.1] (helo=ptb-mxcore01.plus.net) by ptb-spamcore03.plus.net with esmtp (Exim 4.44) id 1DHI9T-0001BH-W3 for dave@picks.force9.co.uk; Fri, 01 Apr 2005 10:09:16 +0100 Received: from post.thorcom.com ([193.82.116.20]) by ptb-mxcore01.plus.net with esmtp (Exim) id 1DHID5-0000ym-G9 for dave@picks.force9.co.uk; Fri, 01 Apr 2005 10:12:59 +0100 Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1DHI8L-00045s-CJ for rs_out_1@blacksheep.org; Fri, 01 Apr 2005 10:08:05 +0100 Received: from [193.82.116.30] (helo=relay.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1DHI8K-00045j-Uk for rsgb_lf_group@blacksheep.org; Fri, 01 Apr 2005 10:08:04 +0100 Received: from hestia.herts.ac.uk ([147.197.200.9]) by relay.thorcom.net with esmtp (Exim 4.43) id 1DHI8J-0006hp-F0 for rsgb_lf_group@blacksheep.org; Fri, 01 Apr 2005 10:08:04 +0100 Received: from [147.197.200.10] (helo=altair2.herts.ac.uk) by hestia.herts.ac.uk with esmtp (Exim 3.22 #1) id 1DHI85-0004oq-00 for rsgb_lf_group@blacksheep.org; Fri, 01 Apr 2005 10:07:49 +0100 Received: from [147.197.164.230] (helo=RD40002) by altair2.herts.ac.uk with esmtp (Exim 3.36 #1) id 1DHI84-0005rV-00 for rsgb_lf_group@blacksheep.org; Fri, 01 Apr 2005 10:07:48 +0100 From: "james moritz" To: rsgb_lf_group@blacksheep.org Date: Fri, 1 Apr 2005 10:07:47 +0100 Message-ID: <000001c5369a$46212d10$e6a4c593@RD40002> MIME-Version: 1.0 X-Priority: 3 (Normal) X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook, Build 10.0.4510 Importance: Normal In-Reply-To: <003201c535ee$e61a50a0$39e4fc3e@l8p8y6> X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1165 X-UH-MailScanner: No Virus detected X-UH-MailScanner-From: j.r.moritz@herts.ac.uk X-SPF-Result: relay.thorcom.net: 147.197.200.9 is neither permitted nor denied by domain of herts.ac.uk X-Spam-Score: 0.0 (/) X-Spam-Report: autolearn=failed,HTML_MESSAGE=0.001 Subject: LF: RE: TX Cores Content-Type: text/html; charset=windows-1252 X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on post.thorcom.com X-Spam-Status: No, hits=0.3 required=5.0 tests=HTML_50_60, HTML_FONTCOLOR_UNKNOWN,HTML_MESSAGE 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-Spam-Filtered: by PlusNet SpamCORE (v4.00) Content-transfer-encoding: 8bit

Dear Mal, LF Group,

No – it is possible to design these transformers with a small air gap, but there does not appear to be a great advantage to doing so because the required number of turns increases, increasing the “copper” losses and offsetting any reduction in core loss. There is always a quite large gap in the original LOPT – often this is produced by inserting plastic film spacers between the core halves. These, and any glue, should be removed so that the core halves fit together perfectly. Sometimes the gap is produced by machining the core legs to unequal lengths, in which case you can’t really use the core in this application.

Cheers, Jim Moritz

73 de M0BMU

-----Original Message-----
From: owner-rsgb_lf_group@blacksheep.org [mailto:owner-rsgb_lf_group@blacksheep.org] On Behalf Of hamilton mal
Sent: 31 March 2005 13:36
To: rsgb_lf_group@blacksheep.org
Subject: LF: TX Cores

Hi All Jim M0BMU.

Jim ur mod to the G0MRF using a TV line output transformer. Did u leave a gap between the cores or not ?

73 de Mal/G3KEV