Return-Path: Received: (qmail 31948 invoked from network); 28 Mar 2005 19:44:37 -0000 Received: from unknown (HELO ptb-spamcore01.plus.net) (192.168.71.1) by ptb-mailstore04.plus.net with SMTP; 28 Mar 2005 19:44:37 -0000 Received: from mailnull by ptb-spamcore01.plus.net with spamcore-l-b (Exim 4.32; FreeBSD) id 1DG0FZ-0003bD-B1 for dave@picks.force9.co.uk; Mon, 28 Mar 2005 20:50:13 +0100 Received: from [192.168.67.2] (helo=ptb-mxcore02.plus.net) by ptb-spamcore01.plus.net with esmtp (Exim 4.32; FreeBSD) id 1DG0FZ-0003bA-82 for dave@picks.force9.co.uk; Mon, 28 Mar 2005 20:50:13 +0100 Received: from post.thorcom.com ([193.82.116.20]) by ptb-mxcore02.plus.net with esmtp (Exim) id 1DG0A9-000CHn-CO for dave@picks.force9.co.uk; Mon, 28 Mar 2005 19:44:37 +0000 Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1DG09U-0002UI-Su for rs_out_1@blacksheep.org; Mon, 28 Mar 2005 20:43:56 +0100 Received: from [193.82.116.30] (helo=relay.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1DG09U-0002U9-Dq for rsgb_lf_group@blacksheep.org; Mon, 28 Mar 2005 20:43:56 +0100 Received: from smtp2.versatel.nl ([62.58.50.89]) by relay.thorcom.net with esmtp (Exim 4.43) id 1DG09R-0001oE-SD for rsgb_lf_group@blacksheep.org; Mon, 28 Mar 2005 20:43:56 +0100 Received: (qmail 22416 invoked by uid 10); 28 Mar 2005 19:43:48 -0000 Received: (vexira-qq 22319-484AEA30 invoked from network) 28 Mar 2005 21:43:47 +0200 Received: from unknown (HELO ibm) ([62.59.190.16]) (envelope-sender ) by smtp2.versatel.nl (qmail-ldap-1.03) with SMTP for < >; 28 Mar 2005 19:43:47 -0000 Message-ID: <000801c533ce$756d3ce0$2102000a@ibm> From: "Dick" To: rsgb_lf_group@blacksheep.org References: <001301c533a6$e3f37c60$2102000a@ibm> <004701c533c7$5f9b2a00$546ca450@preinstapdq0tf> Date: Mon, 28 Mar 2005 21:43:45 +0200 MIME-Version: 1.0 X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 5.00.2615.200 X-MimeOLE: Produced By Microsoft MimeOLE V5.00.2615.200 X-AntiVirus: checked by Vexira MailArmor (version: 2.0.1.16; VAE: 6.30.0.2; VDF: 6.30.0.11; host: postbode02.zonnet.nl) X-SPF-Result: relay.thorcom.net: 62.58.50.89 is neither permitted nor denied by domain of zonnet.nl X-Spam-Score: 0.5 (/) X-Spam-Report: autolearn=no,FROM_ENDS_IN_NUMS=0.516 Subject: LF: Re: 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=1.9 required=5.0 tests=FROM_ENDS_IN_NUMS, 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) Well that might be the answer!!!!!!!! I am using 15 turns of 2.36mm wire. The 50 ohm tap is at 9 turns. I will try again ith more turns of a bit thinner wire to see what happens. Thanks Niels! 73, Dick PA4VHF ----- Original Message ----- From: Niels Rudberg J?rgensen To: Sent: Monday, March 28, 2005 8:52 PM Subject: LF: Re: the use of Epcos cores on LF > > ----- 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+ >