Return-Path: Received: from post.thorcom.com (post.thorcom.com [195.171.43.25]) by mtain-dg06.r1000.mx.aol.com (Internet Inbound) with ESMTP id A1F16380000A5; Thu, 12 Jan 2012 05:53:09 -0500 (EST) Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1RlIGS-0006q4-KW for rs_out_1@blacksheep.org; Thu, 12 Jan 2012 10:52:12 +0000 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1RlIGR-0006pv-VC for rsgb_lf_group@blacksheep.org; Thu, 12 Jan 2012 10:52:11 +0000 Received: from nm11-vm0.bullet.mail.ukl.yahoo.com ([217.146.183.244]) by relay1.thorcom.net with smtp (Exim 4.63) (envelope-from ) id 1RlIGR-0001RA-Sl for rsgb_lf_group@blacksheep.org; Thu, 12 Jan 2012 10:52:11 +0000 Received: from [217.146.183.180] by nm11.bullet.mail.ukl.yahoo.com with NNFMP; 12 Jan 2012 10:52:06 -0000 Received: from [217.146.183.74] by tm11.bullet.mail.ukl.yahoo.com with NNFMP; 12 Jan 2012 10:52:06 -0000 Received: from [127.0.0.1] by omp1035.mail.ukl.yahoo.com with NNFMP; 12 Jan 2012 10:52:06 -0000 X-Yahoo-Newman-Property: ymail-3 X-Yahoo-Newman-Id: 59773.80612.bm@omp1035.mail.ukl.yahoo.com Received: (qmail 93667 invoked by uid 60001); 12 Jan 2012 10:52:06 -0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=yahoo.co.uk; s=s1024; t=1326365525; bh=x9kyBylLWdDK380g0POI2QMSVLfUzVGznWY4cnNi9WI=; h=X-YMail-OSG:Received:X-Mailer:References:Message-ID:Date:From:Reply-To:Subject:To:In-Reply-To:MIME-Version:Content-Type; b=ejIJTSFMKfzdThYLIopa24IR+2gel5o5/+sNPZ576m3FwFTq5UI8yDbFD77uTMn6o1ivSNJ/ELhBhCtq/xha5S9Z5WQ4Rg2eKhQYplYvyCIafjTqXvEh+lUepC86ijAdTCk859mU8NlhduNlLbpMYtD9UbRJy1oDKcZwLZCn0uQ= DomainKey-Signature:a=rsa-sha1; q=dns; c=nofws; s=s1024; d=yahoo.co.uk; h=X-YMail-OSG:Received:X-Mailer:References:Message-ID:Date:From:Reply-To:Subject:To:In-Reply-To:MIME-Version:Content-Type; b=w3RVmXN4uck5ThPv5Ap7O7JftHPbL8vM4vKwc40sNIW4KvXql6iEMeeMIgiPIgpN4C48ZtoI5wsBtwR6wsDaH2YI16XW2W8Q09oVqnNdEUjT0lhTIq8V/FD+wy25ZzmU3lGyGr7UQHFJvGQSVp6FSjhaLK0fEBMC7yMiWrlrv2A=; X-YMail-OSG: Vl3L5hMVM1lAahgOmhEJclH5DBBNxPQAZdrCR_gcecjGKU9 Q8fqTaimMKZ0NgMnx_LO6jdVbdVUxRFSHaelOvV4jBbL0Qe53o2k4oKE9Wur YF5q8HK6FPv4RGJwEpurAepgQD3WS.3gioKjKlLHoIsOBmS9KNN1462tpuSs zRA3jY3NMMJP.yk_sDZcYSBl562Hb3BxdBcU0ZHEgY7E_3azgFwK3XI1PfsM Su7jj0egPOfDX6RmNXh8Y4h5hd8nmK5boctnJWjIFisI_5wJ7GRLpAShU2wy Kknt.6OHdnaH9rOVwSAgUKW1tkjYZEf.xjAOeAKgc7K5bxRLwFV8LuUBrvIu uUy.CRV5ysQfYU2C_9xu5SgepsyzvKCK3iQr0CXQsXUMwh314ZN1az4udLNC Gz5OFxlSvfatKubyrnv0yfTEjDnaVkOJ684fygeK1UPCeGESW3KINy93hA0I ff8S_qzJZ2TeMpZO._.x74DKdLQj5Tbn5TL5aQRBbIbly6lCNrsAcOmqa Received: from [86.137.246.228] by web28108.mail.ukl.yahoo.com via HTTP; Thu, 12 Jan 2012 10:52:04 GMT X-Mailer: YahooMailWebService/0.8.115.331698 References: <593F4C0651144C339855AFC49ED4329E@computereebf79> Message-ID: <1326365524.91314.YahooMailNeo@web28108.mail.ukl.yahoo.com> Date: Thu, 12 Jan 2012 10:52:04 +0000 (GMT) From: M0FMT To: "rsgb_lf_group@blacksheep.org" In-Reply-To: <593F4C0651144C339855AFC49ED4329E@computereebf79> MIME-Version: 1.0 DomainKey-Status: good (testing) Subject: Re: LF: Tuning inductance for 137kHz receive. Content-Type: multipart/alternative; boundary="1325147710-104640475-1326365524=:91314" X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on post.thorcom.com X-Spam-Level: X-Spam-Status: No, hits=0.8 required=5.0 tests=HTML_30_40,HTML_MESSAGE, TO_ADDRESS_EQ_REAL 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-aol-global-disposition: G X-AOL-SCOLL-SCORE: 0:2:420976384:93952408 X-AOL-SCOLL-URL_COUNT: 0 X-AOL-SCOLL-AUTHENTICATION: mail_rly_antispam_dkim-d268.2 ; domain : yahoo.co.uk DKIM : fail x-aol-sid: 3039ac1d410e4f0ebb950972 X-AOL-IP: 195.171.43.25 X-AOL-SPF: domain : blacksheep.org SPF : none --1325147710-104640475-1326365524=:91314 Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: quoted-printable Hi Martin=0A=A0=0AJust make a variometer two inductors one inside the other= like piston and cylinder and adjust in and out to resonance (I think this = design is the simplest form of variometer mechanically). I use a couple of = plastic paint buckets, mine are 200mm diameter. 3mH looks about right for t= he antenna described but fine=A0inductance=A0adjustment is necessary and it= is best to get as high a 'Q' as you can. The band is very narrow and 'Q' h= elps reduce out of band high power signals. I am in fact describing my TX s= etup the primary inductor is a large 600mm diameter coil tapped. All my ind= uctors are air cored.=0A=A0=0AFor RX you can tune the inductor with a large= variable capacitor strapped across because there are no flash over issues.= It is quite simple to make these tuning coils from scratch a lot of wire t= hough, but I would recommend it.=0A=A0=0ATry Rick Strobbe ON7YD's site high= ly recommended=A0=A0=A0 http://www.strobbe.eu/on7yd/136ant/#Introduction=0A= =A0=0AHope this helps.=0A=A0=0A=A073 es GL Pete M0FMT IO91UX=0A=0AFrom: Mar= tin Evans =0ATo: rsgb_lf_group@blacksheep.or= g =0ASent: Wednesday, 11 January 2012, 20:44=0ASubject: LF: Tuning inductan= ce for 137kHz receive.=0A=0AI use a decade inductance bridge to series tune= my=A0 (approximately) 50m end-fed=A0 inverted U wire for 137kHz.=0A=0AIt u= ses 3mH - 2mH is too little, 4mH is too much. Obviously I need to be able t= o vary this inductance rather more finely and I thought of using a small va= riac (don't laugh!) as a variable inductance, connecting one end, and the t= ap, in series with the wire.=0A=0AAnyone know what the "inductance per turn= ", or total inductance, of such an animal might be?=0A=0AAny idea if it wou= ld work?=0A=0AYes, I know I should wind a coil & tap it, but I like to be d= ifferent!=0A=0AMartin=A0 GW3UCJ=A0 Swansea, South Wales. --1325147710-104640475-1326365524=:91314 Content-Type: text/html; charset=iso-8859-1 Content-Transfer-Encoding: quoted-printable
Hi Martin
 
Just make a variomet= er two inductors one inside the other like piston and cylinder and adjust in and out to resonance (= I think this design is the simplest form of variometer mechanically). I use= a couple of plastic paint buckets, mine are 200mm diameter. 3mH looks abou= t right for the antenna described but fine inductance adjustment = is necessary and it is best to get as high a 'Q' as you can. The band is ve= ry narrow and 'Q' helps reduce out of band high power signals. I am in fact describing my TX setup = the primary inductor is a large 600mm diameter coil tapped. All my inductor= s are air cored.
 
For RX you can tune = the inductor with a large variable capacitor strapped across because there = are no flash over issues= . It is quite simple to make these tuning coils from scratch a lot of wire = though, but I would recommend it.
 
Try Rick Strobbe ON7YD's site highly recommended   = ; http://www.s= trobbe.eu/on7yd/136ant/#Introduction
 
Hope this helps.
 
 73 es GL Pete M0FMT IO91UX
From:= Martin Evans <books@mollies.freeserve.co.uk>
To: rsgb_lf_group@blacksheep.org Sent: Wednesday, 11 Januar= y 2012, 20:44
Subject: L= F: Tuning inductance for 137kHz receive.

I use a decade= inductance bridge to series tune my  (approximately) 50m end-fed = ; inverted U wire for 137kHz.

It uses 3mH - 2mH is too little, 4mH i= s too much. Obviously I need to be able to vary this inductance rather more= finely and I thought of using a small variac (don't laugh!) as a variable inductance,= connecting one end, and the tap, in series with the wire.

Anyone kn= ow what the "inductance per turn", or total inductance, of such an animal m= ight be?

Any idea if it would work?

Yes, I know I should wind= a coil & tap it, but I like to be different!

Martin  GW3UC= J  Swansea, South Wales.



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