Return-Path: Received: (qmail 4791 invoked from network); 28 Mar 2005 17:53:56 -0000 Received: from unknown (HELO ptb-spamcore02.plus.net) (192.168.71.3) by ptb-mailstore01.plus.net with SMTP; 28 Mar 2005 17:53:56 -0000 Received: from mailnull by ptb-spamcore02.plus.net with spamcore-l-b (Exim 4.32; FreeBSD) id 1DFyX6-00096Z-Tl for dave@picks.force9.co.uk; Mon, 28 Mar 2005 19:00:13 +0100 Received: from [192.168.67.3] (helo=ptb-mxcore03.plus.net) by ptb-spamcore02.plus.net with esmtp (Exim 4.32; FreeBSD) id 1DFyX4-00095R-9k for dave@picks.force9.co.uk; Mon, 28 Mar 2005 19:00:10 +0100 Received: from post.thorcom.com ([193.82.116.20]) by ptb-mxcore03.plus.net with esmtp (Exim) id 1DFyTW-0006qY-Hb for dave@picks.force9.co.uk; Mon, 28 Mar 2005 18:56:30 +0100 Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1DFyQX-0002MH-2g for rs_out_1@blacksheep.org; Mon, 28 Mar 2005 18:53:25 +0100 Received: from [193.82.116.30] (helo=relay.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1DFyQW-0002M8-KW for rsgb_lf_group@blacksheep.org; Mon, 28 Mar 2005 18:53:24 +0100 Received: from pfepc.post.tele.dk ([195.41.46.237]) by relay.thorcom.net with esmtp (Exim 4.43) id 1DFyQV-0001M5-91 for rsgb_lf_group@blacksheep.org; Mon, 28 Mar 2005 18:53:24 +0100 Received: from preinstapdq0tf (0x50a46c54.virnxx14.adsl-dhcp.tele.dk [80.164.108.84]) by pfepc.post.tele.dk (Postfix) with SMTP id 0221E262899 for ; Mon, 28 Mar 2005 19:52:45 +0200 (CEST) Message-ID: <004701c533c7$5f9b2a00$546ca450@preinstapdq0tf> From: "Niels Rudberg J?rgensen" To: rsgb_lf_group@blacksheep.org References: <001301c533a6$e3f37c60$2102000a@ibm> Date: Mon, 28 Mar 2005 20:52:36 +0200 MIME-Version: 1.0 X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2800.1437 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1441 X-SPF-Result: relay.thorcom.net: domain of post.tele.dk designates 195.41.46.237 as permitted sender X-Spam-Score: 0.0 (/) X-Spam-Report: autolearn=failed,none Subject: LF: Re: the use of Epcos cores on LF Content-Type: text/plain; charset=iso-8859-1; format=flowed Content-Transfer-Encoding: 8bit X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on post.thorcom.com X-Spam-Level: * X-Spam-Status: No, hits=1.1 required=5.0 tests=MAILTO_TO_SPAM_ADDR 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 (v3.00) ----- Original Message ----- From: "Dick" To: Sent: Monday, March 28, 2005 5:00 PM Subject: LF: the use of Epcos cores on LF > A question, especially for our German members. > > Epcos makes (big) cores of so called N30 material. > I previously used an 58mm core to match 50 Ohm to 135Ohm, but it got > really hot at around 400-500Watt or so. > I wonder if this is normal or not (Ui=4300) > > These cores are relatively cheap, so I hoped it was a good solution for big > (output) transformers. > Now I am not to sure anymore........... > > Also interested to know if anyone has experience in using a low beverage, > let's say 400-500m long at 1m heigth as TX antenna. > Not earthed/resistor at the end, just a simple very long wire at 1m heigth. > > 73 > > Dick, pa4vhf > The core mentioned is OK for this purpose. I suspect you made the transformer with too few turns. For 500 W (SWR = 1:1) a turns number of 25:40 will be OK. Too few turns causes a too high magnetizing current with subsequent heating of the core. 73 Niels, OZ8NJ+