Return-Path: X-Spam-DCC: paranoid 1170; Body=2 Fuz1=2 Fuz2=2 X-Spam-Checker-Version: SpamAssassin 3.1.3 (2006-06-01) on lipkowski.org X-Spam-Level: X-Spam-Status: No, score=-2.4 required=5.0 tests=BAYES_00,DNS_FROM_AHBL_RHSBL autolearn=no version=3.1.3 Received: from post.thorcom.com (post.thorcom.com [195.171.43.25]) by paranoid.lipkowski.org (8.13.7/8.13.7) with ESMTP id tA2FLg8D020903 for ; Mon, 2 Nov 2015 16:21:42 +0100 Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1ZtGsm-0007PV-3L for rs_out_1@blacksheep.org; Mon, 02 Nov 2015 15:18:52 +0000 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1ZtGsl-0007PM-QS for rsgb_lf_group@blacksheep.org; Mon, 02 Nov 2015 15:18:51 +0000 Received: from know-smtprelay-omc-6.server.virginmedia.net ([80.0.253.70]) by relay1.thorcom.net with esmtp (Exim 4.86) (envelope-from ) id 1ZtGrq-0001dZ-5G for rsgb_lf_group@blacksheep.org; Mon, 02 Nov 2015 15:18:50 +0000 Received: from [192.168.1.6] ([86.31.33.210]) by know-smtprelay-6-imp with bizsmtp id cfHh1r00X4Y1DuW01fHiKU; Mon, 02 Nov 2015 15:17:42 +0000 X-Originating-IP: [86.31.33.210] X-Spam: 0 X-Authority: v=2.1 cv=P+nH/X0u c=1 sm=1 tr=0 a=jn/JOh/JfiX48zzdjRLp/g==:117 a=jn/JOh/JfiX48zzdjRLp/g==:17 a=NLZqzBF-AAAA:8 a=kj9zAlcOel0A:10 a=PaHEi9XbAAAA:8 a=oCcaPWc0AAAA:8 a=a0oLj6lkQM159s54c54A:9 a=CjuIK1q_8ugA:10 a=-FEs8UIgK8oA:10 a=NWVoK91CQyQA:10 From: "Mike Dennison" To: rsgb_lf_group@blacksheep.org Date: Mon, 02 Nov 2015 15:17:39 -0000 MIME-Version: 1.0 Message-ID: <56377E93.4912.12B1B1B@mike.dennison.ntlworld.com> In-reply-to: References: <1887849276.20151030143118@chriswilson.tv>, <56375E6E.24975.AD8B5E@mike.dennison.ntlworld.com>, X-mailer: Pegasus Mail for Windows (4.41) Content-description: Mail message body X-Scan-Signature: ead411ce91f9601ce3974c7575797436 Subject: Re: Re[2]: LF: Zmag of 45.6 Ohms OK, or should I try for better? Content-type: text/plain; charset=US-ASCII 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 2.56 on 10.1.3.10 Status: O X-Status: X-Keywords: X-UID: 4791 Well, I specified the core type as Chris was originally using a different type, but of course the size is relevant. The diameter is 55mm and I use two cores, one on top of the other, to reduce heat. Mike, G3XDV ========== > 3C90 is a type of ferrite material, and doesn't specify a transformer > type. > > What is the Ae (cross sectional area) of that core? > Or just the diameter to work it out from? > > Andy > > > On 2 November 2015 at 13:00, Mike Dennison > wrote: > > > Chris, my 3C90 transformer has about 16 turns on each winding. (I > > say approximately as I need to adjust by a turn or two between > > summer and winter due to absorption/detuning by trees. I would > > suggest using the thickest wire you have in case you want to run > > higher power in the furture. > > > > As for the variometer, mine covers about 200-500mH and this will > > tune about twice the width of the 136kHz band (in conjunction with > > my big coil). Coincidentally it also tunes the 472kHz band when the > > big coil is removed. > > > > Mike, G3XDV > > ========== > > > > > yes, I still have trouble with the workshop alarm going off when I > > > TX, but seemingly only at night, for whatever reason! Isolation is > > > something I need to add. I have a 3C90 core spare and will wind a > > > 1 : 1 transformer for now, just for isolation. How many turns > > > should I use for best efficiency? I will probably use either 1.5 > > > mm enamelled wire, or maybe some Teflon covered stuff. > > > > > > I also need to tame the variometer, it's obviously got far too > > > many turns on it as just a couple of degrees moves resonance a > > > long way. I picked up a 2 axis variometer, possibly a goniometer, > > > that I may ise, with a motor drive. Photos at > > > http://www.chriswilson.tv/goniometer.zip > > > > > > I only gave a fiver for it, so no big deal if it doesn't work out, > > > but I am about to check what inductances it covers. I think it > > > should withstand the voltages OK. What do you reckon? It would be > > > easier to motor drive then the variometer in my loading coil. > > > > > > Thanks for the kind words about my progress. Most thanks should go > > > to G3YXM for helping me get my amp done and reliable, he's been a > > > Godsend, as have you gentlemen on here. > > > > > > > > > > I agree with Stefan. A transformer (using a suitable core > > > > material such as 3C90) gives you more flexibility in the future > > > > It also provides the opportunity to isolate the RF ground from > > > > the mains supply ground which can improve EMC both on transmit > > > > and receive. > > > > > > > Well done so far. Your signal is very impressive with such low > > > > RF power. > > > > > > > Mike, G3XDV > > > > ========== > > > > > > > > > > > > > > > > > > > > > > > > -- > > > Best regards, > > > Chris mailto:chris@chriswilson.tv > > > > > > > > > > > > > > > ----- > > > No virus found in this message. > > > Checked by AVG - www.avg.com > > > Version: 2016.0.7163 / Virus Database: 4457/10921 - Release Date: > > > 10/31/15 > > > > > > > > > > > > > > > ----- > No virus found in this message. > Checked by AVG - www.avg.com > Version: 2016.0.7163 / Virus Database: 4457/10933 - Release Date: > 11/02/15