Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on lipkowski.org X-Spam-Level: X-Spam-Status: No, score=-2.3 required=5.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, RCVD_IN_DNSWL_MED,SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 X-Spam-DCC: : mailn 1480; Body=2 Fuz1=2 Fuz2=2 Received: from post.thorcom.com (post.thorcom.com [195.171.43.25]) by lipkowski.org (8.14.4/8.14.4/Debian-8+deb8u1) with ESMTP id v2DAcfu6002433 for ; Mon, 13 Mar 2017 11:38:42 +0100 Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1cnNJp-0000aY-TA for rs_out_1@blacksheep.org; Mon, 13 Mar 2017 10:35:13 +0000 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1cnNJp-0000aP-BH for rsgb_lf_group@blacksheep.org; Mon, 13 Mar 2017 10:35:13 +0000 Received: from mailfe05.swip.net ([212.247.154.129] helo=swip.net) by relay1.thorcom.net with esmtp (Exim 4.89) (envelope-from ) id 1cnNJi-0004dL-VL for rsgb_lf_group@blacksheep.org; Mon, 13 Mar 2017 10:35:12 +0000 X-T2-Spam-Status: No, hits=0.8 required=5.0 tests=BAYES_50 Received: from [81.224.109.193] (account cxu-dcw-tyr@tele2.se HELO [192.168.1.7]) by mailfe05.swip.net (CommuniGate Pro SMTP 5.4.4) with ESMTPSA id 712351327 for rsgb_lf_group@blacksheep.org; Mon, 13 Mar 2017 11:34:57 +0100 To: rsgb_lf_group@blacksheep.org References: <15a98cc579c-d3b-de27@webprd-a58.mail.aol.com> <08c5eae2-8c19-da4d-f5b9-30b83712932f@psk31.plus.com> <58BAEA1D.5050802@posteo.de> <58BB4FA5.4080601@posteo.de> <553e8ee3-01a4-5840-0353-e82b320b1751@psk31.plus.com> <58BC3339.6060301@posteo.de> <58BC8101.8040206@posteo.de> <58BF3619.8030704@posteo.de> <6d35e8fc-fffc-1d33-250b-5c8dfd1d8f06@abelian.org> <58C13456.5040904@posteo.de> <58C54163.5000509@posteo.de> From: Johan Bodin Message-ID: Date: Mon, 13 Mar 2017 11:34:55 +0100 User-Agent: Mozilla/5.0 (Windows NT 6.3; WOW64; rv:45.0) Gecko/20100101 Thunderbird/45.8.0 MIME-Version: 1.0 In-Reply-To: X-Scan-Signature: 086f3faad0220c9ae57a7913e711a86d Subject: Re: LF: VLF in NA, PVC coil bodies/VLF converter Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit 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-Scanned-By: MIMEDefang 2.75 Status: RO X-Status: X-Keywords: X-UID: 10893 Hi Joe, I have almost forgotten that old LF converter. I just rediscovered the web page in an Internet museum! :-) http://home4.swipnet.se/~w-41522/lfconv/lfconv.html Regarding T1, inductance depends on the lower frequency limit. I recall that the AL of that 3F3 core (T1) is 0.9uH*n^2 so 25 turns result in about 560uH. A rule of thumb for transformers is to aim for a winding reactance of 5 * system impedance at the lowest frequency of operation which seems to be around 70kHz in this case. The converter will go lower, of course, but the transformer reactance will shunt more of the signal. The CMOS switch mixer is less sensitive to termination than a diode ring mixer, I think, so the diplexer is not very critical. You can reduce the Q to 1 to make tuning less critical and reduce the loss in the diplexer. Just found this page: http://www.changpuak.ch/electronics/calc_16a.php Increasing the impedance around the CMOS switch will redeuce switch losses and perhaps also improve linearity. You could try to increase the number of turns on T1 secondaries by 2 or 3 for a 200 or 450 ohm level. Design the diplexer for this impedance and put a corresponding step-down transformer at the 10MHz output. Just an idea... 73 de Johan SM6LKM jcraig@mun.ca wrote: > > Johan, I'd like to build your FB VLF converter iand use a 10 MHz LO. > L1 C5 and C6 and L2 were scaled for 10 from 4 MHz but a T1 core > is not handy. Is 5 mH per winding satisfactory?