Received: from post.thorcom.com (post.thorcom.com [195.171.43.25]) by mtain-dk02.r1000.mx.aol.com (Internet Inbound) with ESMTP id E928E38000123; Mon, 12 Sep 2011 09:23:24 -0400 (EDT) Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1R36T4-0001Aw-Ov for rs_out_1@blacksheep.org; Mon, 12 Sep 2011 14:22:34 +0100 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1R36T3-0001An-RN for rsgb_lf_group@blacksheep.org; Mon, 12 Sep 2011 14:22:33 +0100 Received: from nm18.bullet.mail.ird.yahoo.com ([77.238.189.71]) by relay1.thorcom.net with smtp (Exim 4.63) (envelope-from ) id 1R36T2-0003a4-9p for rsgb_lf_group@blacksheep.org; Mon, 12 Sep 2011 14:22:33 +0100 Received: from [77.238.189.232] by nm18.bullet.mail.ird.yahoo.com with NNFMP; 12 Sep 2011 13:22:26 -0000 Received: from [212.82.108.123] by tm13.bullet.mail.ird.yahoo.com with NNFMP; 12 Sep 2011 13:22:26 -0000 Received: from [127.0.0.1] by omp1032.mail.ird.yahoo.com with NNFMP; 12 Sep 2011 13:22:26 -0000 X-Yahoo-Newman-Property: ymail-3 X-Yahoo-Newman-Id: 449942.18279.bm@omp1032.mail.ird.yahoo.com Received: (qmail 20092 invoked by uid 60001); 12 Sep 2011 13:22:26 -0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=yahoo.com; s=s1024; t=1315833746; bh=D1Nn2K62Rc7D+KmUb9ksQhQvqBk2keKfcs1Ry2I+FxU=; h=X-YMail-OSG:Received:X-Mailer:References:Message-ID:Date:From:Reply-To:Subject:To:In-Reply-To:MIME-Version:Content-Type; b=31sgAKjP4LcwixPNeuYOa5AaToiZYh+ygmtMj89ttxKQnqzk9DulqMb1L905Hs+Hv9mvhf2wmF06cnLdy7tl/7ciDGqYGBd+GdIHDTYpTKQ4/3Zh2iDerJBsUKBphE+0BPKIpq59ohPYouz62vm3Se2GfhgXTURLo6ePIaZyb2g= DomainKey-Signature:a=rsa-sha1; q=dns; c=nofws; s=s1024; d=yahoo.com; h=X-YMail-OSG:Received:X-Mailer:References:Message-ID:Date:From:Reply-To:Subject:To:In-Reply-To:MIME-Version:Content-Type; b=2lYUAc/p6CzSA7Lb7Bq8bQNzXxE8GcCMtBi/41q4NEbeqL4ndNtHgFuOZ6elplnF7mKAFBJ0h6OiwiIw2FFFpFUDPElxLPh+yvQMmFJ7k+punw8MDhw+2Iw9nPOVF+WuhRJbVfKpyjjMTWjUZ35gQlt50LdGXD9bproqBoCfWKg=; X-YMail-OSG: 2vOkCvAVM1kZ2FB4DnOR5_LZgeZ8a4urvW2uqpL216fl_h3 MvCTS5MZ1ZkFSmTXoe6Y_TOfYHREDVLLhRE5tk1KdKmrSbebtRPfgrRjMI6_ u1WUNuyW4YL1w8IT6aPp_jvEMgUTt0_b9B1pBtPOfvrSggPtnlLYqIprFsza cGsEk3rhEyogJvOsvXohMhQYxjtag1kYuyeMlQJcyeFOeiVCYQVNOWOagxLq wE1zfzFKP1cAY.B2LNEIb_etLM5b7PB0Il0ohfWzbJytvaFYhc1CRD1BxDxs punEkjs1ecB6c8GDdJHAlCA08WECl8.dezjVkNSOeHAzq37X2kTL5D.g7VnR ofFRu1QRHYLMYZjUsRCiRILOiM8L41QVQcEoM0IOyNBODOhIFTtC3dlr_RNw c Received: from [151.99.187.181] by web29503.mail.ird.yahoo.com via HTTP; Mon, 12 Sep 2011 14:22:26 BST X-Mailer: YahooMailWebService/0.8.113.315625 References: <4E6E0AD4.4838.465714@mike.dennison.ntlworld.com> Message-ID: <1315833746.18312.YahooMailNeo@web29503.mail.ird.yahoo.com> Date: Mon, 12 Sep 2011 14:22:26 +0100 (BST) From: Daniele Tincani To: "rsgb_lf_group@blacksheep.org" In-Reply-To: <4E6E0AD4.4838.465714@mike.dennison.ntlworld.com> MIME-Version: 1.0 DomainKey-Status: good (testing) X-Spam-Score: 1.4 (+) X-Spam-Report: autolearn=disabled,HTML_MESSAGE=0.001,HTML_TINY_FONT=1.425 Subject: Re: LF: Ferrite antennas Content-Type: multipart/alternative; boundary="-73641666-835257246-1315833746=:18312" X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on post.thorcom.com X-Spam-Level: X-Spam-Status: No, hits=1.0 required=5.0 tests=FORGED_YAHOO_RCVD,HTML_20_30, 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: 0:2:468446752:93952408 X-AOL-SCOLL-URL_COUNT: 0 X-AOL-SCOLL-AUTHENTICATION: mail_rly_antispam_dkim-d008.2 ; domain : yahoo.com DKIM : fail x-aol-sid: 3039ac1db4064e6e07cc6990 X-AOL-IP: 195.171.43.25 X-AOL-SPF: domain : blacksheep.org SPF : none ---73641666-835257246-1315833746=:18312 Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: quoted-printable Hello Mike, LF,=0A=A0=0AI'm waiting from ferrites and litz wire to arrive f= rom eBay, then I will be able to start my experiments for a wideband ferrit= e-cored antenna covering as much as possible of LF. Major uncertainties for= me are on the mechanical construction, I mean: inner shielding (between th= e rod and the coil)=A0vs. outer shielding; compact winding vs. longer coil = (how long?);=A0leaving some space between the=A0coil and the core or not;= =A0etc..=0AAs there are so many design parameters to consider, I would like= to fix some at least. So I plan to start with=A0inner shielding only - mad= e by slotted aluminium tube (outer shield can be added later for test); com= pact winding (should be OK with litz); piece of PVC tube used both as a spa= cer (between the rod and the coil) and a isolating mechanical support for 2= -3 stacked rods (20cm each) in further tests.=0AI would like to know if any= one on the LF reflector has comments/results about using a plastic spacer (= e.g. PVC tube) between the core and the coil. The tube is 16mm outer diamet= er, while the ferrites are 10mm. If there are not real advantages in having= more space between the rod and the coil, then I think the aluminium tube u= sed for inner shielding could be sufficient also as the mechanical support = for winding.=0A=A0=0ABest regards=0ADaniele=0A=A0=0A=0ADa: Mike Dennison =0AA: rsgb_lf_group@blacksheep.org=0AInviato: Lun= ed=EC 12 Settembre 2011 14:36=0AOggetto: LF: Ferrite antennas=0A=0AI have b= een following the discussion on ferrite receiving antennas - =0Adue to work= pressures I am a few weeks behind in reading the mail.=0A=0AThe use of thi= s type of antenna for LF amateur radio is not new. I =0Aused it successfull= y as a portable antenna on the old 73kHz band =0Aseveral years ago. =0A=0AI= used the existing winding (LItz) an ordinary long-wave broadcast =0Aradio = antenna. The rod was about 150mm long. The coil, tuned with a =0Alarge fixe= d C and a variable C, formed the drain load of a 2N3819, =0Awith the output= taken from the source. The selectivity was very high =0Aindeed (essential = to reduce the huge commercial signal on the 73kHz =0Aband) and sensitivity = was adequate to overcome the noise level of my =0Avery sensitive Datong LF = converter.=0A=0AThe interesting thing was that Peter, G3LDO, tried to repli= cate this =0Aand had poorer results, perhaps indicating that not all long w= ave =0Aradios had ferrite that worked at 73kHz.=0A=0AMike, G3XDV=0A=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D ---73641666-835257246-1315833746=:18312 Content-Type: text/html; charset=iso-8859-1 Content-Transfer-Encoding: quoted-printable
Hello Mike, LF,
 
I'm waiting from fer= rites and litz wire to arrive from eBay, then I will be able to start my ex= periments for a wideband ferrite-cored antenna covering as much as possible= of LF. Major uncertainties for me are on the mechanical construction, I me= an: inner shielding (between the rod and the coil) vs. outer shielding= ; compact winding vs. longer coil (how long?); leaving some space betw= een the coil and the core or not; etc..
As there are so many= design parameters to consider, I would like to fix some at least. So I pla= n to start with inner shielding only - made by slotted aluminium tube = (outer shield can be added later for test); compact winding (should be OK w= ith litz); piece of PVC tube used both as a spacer (between the rod and the= coil) and a isolating mechanical support for 2-3 stacked rods (20cm each) = in further tests.
I would like to know= if anyone on the LF reflector has comments/results about using a plastic s= pacer (e.g. PVC tube) between the core and the coil. The tube is 16mm outer= diameter, while the ferrites are 10mm. If there are not real advantages in= having more space between the rod and the coil, then I think the aluminium= tube used for inner shielding could be sufficient also as the mechanical s= upport for winding.
 
Best regards<= /div>
Daniele
 

Da: Mike Dennison <mike.dennison@ntlworld.com>
A: rsgb_lf_group@blacksheep.org
Inviato: Luned=EC 12 Settembre 2= 011 14:36
Oggetto: LF: F= errite antennas

I have been following the discussion on ferri= te receiving antennas -
due to work pressures I am a few weeks behind i= n reading the mail.

The use of this type of antenna for LF amateur r= adio is not new. I
used it successfully as a portable antenna on the ol= d 73kHz band
several years ago.

I used the existing winding (LItz) an = ordinary long-wave broadcast
radio antenna. The rod was about 150mm lon= g. The coil, tuned with a
large fixed C and a variable C, formed the dr= ain load of a 2N3819,
with the output taken from the source. The select= ivity was very high
indeed (essential to reduce the huge commercial sig= nal on the 73kHz
band) and sensitivity was adequate to overcome the noi= se level of my
very sensitive Datong LF converter.

The interesti= ng thing was that Peter, G3LDO, tried to replicate this
and had poorer = results, perhaps indicating that not all long wave
radios had ferrite t= hat worked at 73kHz.

Mike, G3XDV
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D


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