Received: from mtain-da05.r1000.mx.aol.com (mtain-da05.r1000.mx.aol.com [172.29.64.77]) by imd-mb08.r1000.mx.aol.com (Inbound Mail Deferral) with ESMTP id A10C17000008D for ; Tue, 16 Aug 2011 11:39:27 -0400 (EDT) Received: from post.thorcom.com (post.thorcom.com [195.171.43.25]) by mtain-da05.r1000.mx.aol.com (Internet Inbound) with ESMTP id 78FF238000081; Tue, 16 Aug 2011 11:39:24 -0400 (EDT) Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1QtLiV-0002mp-77 for rs_out_1@blacksheep.org; Tue, 16 Aug 2011 16:38:11 +0100 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1QtLiU-0002mg-JU for rsgb_lf_group@blacksheep.org; Tue, 16 Aug 2011 16:38:10 +0100 Received: from mail-vw0-f43.google.com ([209.85.212.43]) by relay1.thorcom.net with esmtp (Exim 4.63) (envelope-from ) id 1QtLiN-0007kg-Kr for rsgb_lf_group@blacksheep.org; Tue, 16 Aug 2011 16:38:10 +0100 Received: by vws10 with SMTP id 10so43603vws.16 for ; Tue, 16 Aug 2011 08:37:56 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=mime-version:sender:in-reply-to:references:date :x-google-sender-auth:message-id:subject:from:to:content-type; bh=om4RWNgJw4dTwNMOAZ7O3nniODY8p0GlGk9ls1GB8hc=; b=jEo+Uol4C1dN6+au5fSjf0AeDa/yRVyNdkw/UccY5akr1eZv72LEhfqEUCG05zOp1J 7DKoA5tufl5eaQ+Bggtts0uOg3kBhNVh5zlEVUmr9lLbGDsrqCDHn7VnpNCkgf4TVUfo EERHeHpVe7zjgiLhr9d6nV1NfAS7VYozq7zcw= MIME-Version: 1.0 Received: by 10.52.68.3 with SMTP id r3mr5064641vdt.248.1313509076587; Tue, 16 Aug 2011 08:37:56 -0700 (PDT) Received: by 10.220.203.200 with HTTP; Tue, 16 Aug 2011 08:37:56 -0700 (PDT) In-Reply-To: <1313507382.3851.5.camel@pat-compaq-evo> References: <4E4A4134.4060007@kabelmail.de> <51E78B0C619E4A90B8BBFCEDC5233A38@JimPC> <001601cc5c12$ffe69510$0401a8c0@xphd97xgq27nyf> <1313507382.3851.5.camel@pat-compaq-evo> Date: Tue, 16 Aug 2011 16:37:56 +0100 X-Google-Sender-Auth: 1aSLFRFJpQzZlqZwNbUyi5hvqeU Message-ID: From: Gary - G4WGT To: rsgb_lf_group@blacksheep.org X-Spam-Score: 0.0 (/) X-Spam-Report: autolearn=disabled,HTML_MESSAGE=0.001 Subject: Re: LF: Re: Ferrite Loops Content-Type: multipart/alternative; boundary=20cf3071c68eeb52c204aaa12935 X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on post.thorcom.com X-Spam-Level: X-Spam-Status: No, hits=0.1 required=5.0 tests=HTML_FONTCOLOR_UNSAFE, HTML_MESSAGE 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: 1:2:479175968:93952408 X-AOL-SCOLL-URL_COUNT: 1 X-AOL-SCOLL-AUTHENTICATION: mail_rly_antispam_dkim-m243.2 ; domain : gmail.com DKIM : fail x-aol-sid: 3039ac1d404d4e4a8f2c0587 X-AOL-IP: 195.171.43.25 X-AOL-SPF: domain : blacksheep.org SPF : none --20cf3071c68eeb52c204aaa12935 Content-Type: text/plain; charset=ISO-8859-1 Hi All, I am using this method to increase the range of my variometer for 136kHz band, see :- http://myweb.tiscali.co.uk/wgtaylor/LF%20&%20MF%20Experiments%2012.html 73 Gary - G4WGT On 16 August 2011 16:09, g4gvw wrote: > Mal is spot on with that one. A well-known Chelmsford firm used the > technique in some of their tx units. > > 73 > > > On Tue, 2011-08-16 at 13:49 +0100, mal hamilton wrote: > > Sliding ferrite rods in and out of coils has been used since radio > > began to alter inductance. You will find it in radio receiver IF > > transformers as well as aluminium and brass rods. > > I have used this method in PA coils to adjust inductance to that > > required ie a fine tune tool > > It does not have to be rods any shape of ferrite core will do, the > > same applies to brass and other metals depending what you want to do. > > de > > G3KEV > > > > > > ----- Original Message ----- > > From: Roger Lapthorn > > To: rsgb_lf_group@blacksheep.org > > Sent: Tuesday, August 16, 2011 12:57 PM > > Subject: Re: LF: Re: Ferrite Loops > > > > > > Hi Jim (et al) > > > > Ferrite rods as 5-20W TX loading coils? > > > > As long as the ferrite doesn't saturate am I right in thinking > > that the use of ferrite rods as coil formers for 137 and > > 500kHz is basically "a good idea"? > > > > From personal experience with 5W this worked well at 500kHz so > > I assume that the idea could be translated to 136kHz if using > > separate rods for each 500uH of inductance so the cores of > > each do not saturate. Am I right in thinking that if you > > bundle x cores together (in parallel) the core will saturate > > at x times the power? Making a ferrite rod based variometer > > would be straightforward - PVC tube with cores sliding > > together lengthwise for example. > > > > Engineering large air-spaced loading coils is quite a feat > > whereas making up, for example, 8-10 separate ferrite coils > > with a range of taps on each is quite easy (and small). Less > > wire would be needed so the losses in the coils would be lower > > compared with the air-spaced equivalent. > > > > Is there mileage in this, say up to 15-20W RF? > > > > 73s > > Roger G3XBM > > > > On 16 August 2011 11:53, James Moritz > > wrote: > > Dear Tom, LF Group, > > > > what do you think about an array of many > > parallel mounted ferrite rods, each of them > > carrying only a few windigs, all windings > > connected in series (and then perhaps tuned) > > and the rods arraged in such a way that the > > individual apertures dont touch? Or will this > > lead to the dimensions of a comparable air > > loop ;-) ? > > > > I am sure this would work, but I think you have also > > identified the limitation ;-) Fundamentally, if the > > signal has a particular power density at the receive > > site, the antenna must intercept the signal from a > > certain aperture area in order to deliver a certain > > power to the receiver. So there is a limit to how > > small it can practically be, although the actual shape > > can vary to obtain the same aperture - one could make > > a rough comparison between the short, wide loop vs. > > the long, thin ferrite rod, and a long yagi vs. a > > broadside array of dipoles. > > > > I think an array of ferrite rods might be attractive > > in some circumstances - for instance, you could have > > numerous small rods stacked vertically, to produce a > > "ferrite rod vertical" with a small turning circle but > > a relatively large effective area. > > > > Cheers, Jim Moritz > > 73 de M0BMU > > > > > > > > > > > > > > -- > > http://g3xbm-qrp.blogspot.com/ > > http://www.g3xbm.co.uk > > http://www.youtube.com/user/g3xbm > > https://sites.google.com/site/sub9khz/ > > > > -- > 73 es gd dx de pat g4gvw > qth nr felixstowe uk > (east coast, county of suffolk) > > > --20cf3071c68eeb52c204aaa12935 Content-Type: text/html; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable Hi All,

I am using this method to increase the range of = my variometer for 136kHz band, see :-


73

Gary - G4WGT

=
On 16 August 2011 16:09, g4gvw <g4gvw@aol.com> wrot= e:
Mal is spot on with that one. A well-known = Chelmsford firm used the
technique in some of their tx units.

73


On Tue, 2011-08-16 at 13:49 +0100, mal hamilton wrote:
> Sliding ferrite rods in and out of coils has been used since radio
> began to alter inductance. You will find it in radio receiver IF
> transformers as well as aluminium and brass rods.
> I have used this method in PA coils to adjust inductance to that
> required ie a fine tune tool
> It does not have to be rods any shape of ferrite core will do, the
> same applies to brass and other metals depending what you want to do.<= br> > de
> G3KEV
>
>
> =A0 =A0 =A0 =A0 ----- Original Message -----
> =A0 =A0 =A0 =A0 From: Roger Lapthorn
> =A0 =A0 =A0 =A0 To: rs= gb_lf_group@blacksheep.org
> =A0 =A0 =A0 =A0 Sent: Tuesday, August 16, 2011 12:57 PM
> =A0 =A0 =A0 =A0 Subject: Re: LF: Re: Ferrite Loops
>
>
> =A0 =A0 =A0 =A0 Hi Jim (et al)
>
> =A0 =A0 =A0 =A0 Ferrite rods as 5-20W TX loading coils?
>
> =A0 =A0 =A0 =A0 As long as the ferrite doesn't saturate am I right= in thinking
> =A0 =A0 =A0 =A0 that the use of ferrite rods as coil formers for 137 a= nd
> =A0 =A0 =A0 =A0 500kHz is basically "a good idea"?
>
> =A0 =A0 =A0 =A0 From personal experience with 5W this worked well at 5= 00kHz so
> =A0 =A0 =A0 =A0 I assume that the idea could be translated to 136kHz i= f using
> =A0 =A0 =A0 =A0 separate rods for each 500uH of inductance so the core= s of
> =A0 =A0 =A0 =A0 each do not saturate. Am I right in thinking that if y= ou
> =A0 =A0 =A0 =A0 bundle x cores together (in parallel) the core will sa= turate
> =A0 =A0 =A0 =A0 at x times the power? Making a ferrite rod based vario= meter
> =A0 =A0 =A0 =A0 would be straightforward - PVC tube with cores sliding=
> =A0 =A0 =A0 =A0 together lengthwise for example.
>
> =A0 =A0 =A0 =A0 Engineering large air-spaced loading coils is quite a = feat
> =A0 =A0 =A0 =A0 whereas making up, for example, 8-10 separate ferrite = coils
> =A0 =A0 =A0 =A0 with a range of taps on each is quite easy (and small)= . Less
> =A0 =A0 =A0 =A0 wire would be needed so the losses in the coils would = be lower
> =A0 =A0 =A0 =A0 compared with the air-spaced equivalent.
>
> =A0 =A0 =A0 =A0 Is there mileage in this, say up to 15-20W RF?
>
> =A0 =A0 =A0 =A0 73s
> =A0 =A0 =A0 =A0 Roger G3XBM
>
> =A0 =A0 =A0 =A0 On 16 August 2011 11:53, James Moritz
> =A0 =A0 =A0 =A0 <ja= mes.moritz@btopenworld.com> wrote:
> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 Dear Tom, LF Group,
>
> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 what do you think abou= t an array of many
> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 parallel mounted ferri= te rods, each of them
> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 carrying only a few wi= ndigs, all windings
> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 connected in series (a= nd then perhaps tuned)
> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 and the rods arraged i= n such a way that the
> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 individual apertures d= ont touch? Or will this
> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 lead to the dimensions= of a comparable air
> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 loop ;-) ?
>
> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 I am sure this would work, but I think= you have also
> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 identified the limitation ;-) Fundamen= tally, if the
> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 signal has a particular power density = at the receive
> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 site, the antenna must intercept the s= ignal from a
> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 certain aperture area in order to deli= ver a certain
> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 power to the receiver. So there is a l= imit to how
> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 small it can practically be, although = the actual shape
> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 can vary to obtain the same aperture -= one could make
> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 a rough comparison between the short, = wide loop vs.
> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 the long, thin ferrite rod, and a long= yagi vs. a
> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 broadside array of dipoles.
>
> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 I think an array of ferrite rods might= be attractive
> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 in some circumstances - for instance, = you could have
> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 numerous small rods stacked vertically= , to produce a
> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 "ferrite rod vertical" with = a small turning circle but
> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 a relatively large effective area.
>
> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 Cheers, Jim Moritz
> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 73 de M0BMU
>
>
>
>
>
>
> =A0 =A0 =A0 =A0 --
> =A0 =A0 =A0 =A0 http://g3xbm-qrp.blogspot.com/
> =A0 =A0 =A0 =A0 h= ttp://www.g3xbm.co.uk
> =A0 =A0 =A0 =A0 http://www.youtube.com/user/g3xbm
> =A0 =A0 =A0 =A0 https://sites.google.com/site/sub9khz/
>

--
73 es gd dx de pat g4gvw
=A0qth nr felixstowe uk
(east coast, county of suffolk)



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