Envelope-to: dave@picks.force9.co.uk Delivery-date: Tue, 17 May 2005 15:13:21 +0100 Received: from pih-spamcore03.plus.net ([192.168.71.7]) by pih-mxcore08.plus.net with esmtp (PlusNet MXCore v1.0) id 1DY2oy-000076-35 for dave@picks.force9.co.uk; Tue, 17 May 2005 15:13:21 +0100 Received: from Debian-exim by pih-spamcore03.plus.net with spam-scanned (Exim 4.50) id 1DY2ow-00084M-US for dave@picks.force9.co.uk; Tue, 17 May 2005 15:13:19 +0100 Received: from [192.168.101.77] (helo=pih-mxcore11.plus.net) by pih-spamcore03.plus.net with esmtp (Exim 4.50) id 1DY2ow-00084J-Sa for dave@picks.force9.co.uk; Tue, 17 May 2005 15:13:18 +0100 Received: from post.thorcom.com ([193.82.116.20]) by pih-mxcore11.plus.net with esmtp (PlusNet MXCore v1.0) id 1DY2ow-0003tJ-Lx for dave@picks.force9.co.uk; Tue, 17 May 2005 15:13:18 +0100 Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1DY2nf-0003Jp-Np for rs_out_1@blacksheep.org; Tue, 17 May 2005 15:11:59 +0100 Received: from [193.82.116.30] (helo=relay.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1DY2nf-0003Jg-AB for rsgb_lf_group@blacksheep.org; Tue, 17 May 2005 15:11:59 +0100 Received: from fh1025.dia.cp.net ([64.97.168.35] helo=n082.sc1.cp.net) by relay.thorcom.net with esmtp (Exim 4.43) id 1DY2nc-0007sD-R7 for rsgb_lf_group@blacksheep.org; Tue, 17 May 2005 15:11:59 +0100 Received: from l8p8y6 (62.252.208.55) by n082.sc1.cp.net (7.0.043) id 4288DFB70003F3AB for rsgb_lf_group@blacksheep.org; Tue, 17 May 2005 14:11:53 +0000 Message-ID: <000c01c55a6e$8d82f740$37d0fc3e@l8p8y6> From: "hamilton mal" To: rsgb_lf_group@blacksheep.org Date: Tue, 17 May 2005 00:24:59 +0100 MIME-Version: 1.0 X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 5.50.4807.1700 X-MimeOLE: Produced By Microsoft MimeOLE V5.50.4807.1700 X-SPF-Result: relay.thorcom.net: 64.97.168.35 is neither permitted nor denied by domain of virgin.net Subject: LF: CORES Content-Type: text/html; charset=windows-1252 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 (v4.00s) Content-transfer-encoding: 8bit

I have been winding some transformers recently and have been getting some odd results.

All cores have a prim of 9 turns and 27 turns sec.

1. 3C85 58 mm diam Prim inductance 167uh Sec 744 uh

2. Same material abt same size but E core Prim 292 uh Sec 2810 uh no gap.

3. Material unknown out of a smps similar size Prim 21 uh Sec 178 uh no gap

4. TV lopt core again abt same size Prim 79 uh Sec 865 uh no gap

The Prim wire is litz 2mm and sec 1mm copper enam wire in all cases.

1 and 2 seem to have a big difference considering the same material, 3 must have a low u.

Has anyone else tried comparisons of cores.

If cores are selected at random and not checked there would be a big variation in results even using the same turns ratio.

The above are intended as output matching transformers in the FET amps like the YXM and MRF class D/E design.

I normally use 1 in my amps but have tried 3 and in spite of the big difference in values it does seem to work and I have not noticed any difference in RF output, which seems strange.

73 de Mal/G3KEV