Return-Path: Received: (qmail 50858 invoked from network); 27 Sep 2004 09:56:52 -0000 Received: from unknown (HELO ptb-spamcore02.plus.net) (192.168.71.3) by ptb-mailstore02.plus.net with SMTP; 27 Sep 2004 09:56:52 -0000 Received: from mailnull by ptb-spamcore02.plus.net with spamcore-l-b (Exim 4.32; FreeBSD) id 1CBsJu-000OCD-Nj for dave@picks.force9.co.uk; Mon, 27 Sep 2004 11:01:24 +0100 Received: from [192.168.67.2] (helo=ptb-mxcore02.plus.net) by ptb-spamcore02.plus.net with esmtp (Exim 4.32; FreeBSD) id 1CBsJu-000OCA-L4 for dave@picks.force9.co.uk; Mon, 27 Sep 2004 11:01:22 +0100 Received: from post.thorcom.com ([193.82.116.20]) by ptb-mxcore02.plus.net with esmtp (Exim) id 1CBsFW-000Fo2-Cg for dave@picks.force9.co.uk; Mon, 27 Sep 2004 09:56:50 +0000 Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1CBsEF-0002bi-AH for rs_out_1@blacksheep.org; Mon, 27 Sep 2004 10:55:31 +0100 Received: from [193.82.116.30] (helo=relay.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1CBsEE-0002bZ-Un for rsgb_lf_group@blacksheep.org; Mon, 27 Sep 2004 10:55:30 +0100 Received: from smtp802.mail.ukl.yahoo.com ([217.12.12.139]) by relay.thorcom.net with smtp (Exim 4.41) id 1CBsEA-00048l-TI for rsgb_lf_group@blacksheep.org; Mon, 27 Sep 2004 10:55:31 +0100 Received: from unknown (HELO Main) (Alan.Melia@81.131.210.101 with login) by smtp802.mail.ukl.yahoo.com with SMTP; 27 Sep 2004 09:55:21 -0000 Message-ID: <006e01c4a478$0c006600$6507a8c0@Main> From: "Alan Melia" To: rsgb_lf_group@blacksheep.org References: <006701c4a41a$a3893640$216e7ad5@jgtdiynm> Date: Mon, 27 Sep 2004 10:02:23 +0100 MIME-Version: 1.0 X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 5.50.4522.1200 X-MimeOLE: Produced By Microsoft MimeOLE V5.50.4522.1200 X-SPF-Result: relay.thorcom.net: 217.12.12.139 is neither permitted nor denied by domain of btinternet.com X-Spam-Score: 0.1 (/) X-Spam-Report: autolearn=no,RCVD_IN_SORBS=0.1 Subject: LF: Re: Re: fluted ferrite cores 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-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-Spam-Filtered: by PlusNet SpamCORE (v3.00) Hi Jim, Thanks for that, It seems that these could well be useful. they certainly work well tuning my receive solenoid. You certainly get a good sized lump or ferrite for your £3-00 Cheers de Alan G3NYK alan.melia(at)btinternet.com ----- Original Message ----- From: "James Moritz" To: Sent: 26 September 2004 23:45 Subject: LF: Re: fluted ferrite cores Dear Alan, LF Group, The fluted ferrite rods are probably "impeder rods" - these are used for induction welding of the seams in metal tubing produced by rolling strip metal. They fit inside the tube at the point where the weld is being made. Their purpose is to force the induced current to flow through the weld, rather than around the circumference of the tube; there is a fairly good description at: http://www.impeder.com/Efficiency/efficiency.html The purose of the flutes is to allow the circulation of cooling water, allthough it may also be significant in reducing eddy currents. My old Philips ferrite data book lists these as available in either 3C85 or 3D3 (a somewhat lower permeability ferrite otherwise similar to 3C85). The induction welding application normally operates in the LF/MF range at the 10s of kW level - potentially these might be useful in an LF TX loading coil application, if a coil using them can be made with high enough Q... Cheers, Jim Moritz 73 de M0BMU