Received: from post.thorcom.com (post.thorcom.com [195.171.43.25]) by mtain-de05.r1000.mx.aol.com (Internet Inbound) with ESMTP id 04824380000F7; Mon, 15 Aug 2011 13:31:25 -0400 (EDT) Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1Qt0zJ-0005w5-Aq for rs_out_1@blacksheep.org; Mon, 15 Aug 2011 18:30:09 +0100 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1Qt0zI-0005vw-HF for rsgb_lf_group@blacksheep.org; Mon, 15 Aug 2011 18:30:08 +0100 Received: from relay2.uni-heidelberg.de ([129.206.210.211]) by relay1.thorcom.net with esmtp (Exim 4.63) (envelope-from ) id 1Qt0zG-0007dM-UY for rsgb_lf_group@blacksheep.org; Mon, 15 Aug 2011 18:30:08 +0100 Received: from freitag.iup.uni-heidelberg.de (freitag.iup.uni-heidelberg.de [129.206.29.204]) by relay2.uni-heidelberg.de (8.13.8/8.13.8) with ESMTP id p7FHU5Xn014127 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=NO) for ; Mon, 15 Aug 2011 19:30:06 +0200 Received: from [129.206.22.206] (pc206.iup.uni-heidelberg.de [129.206.22.206]) by freitag.iup.uni-heidelberg.de (8.12.11.20060308/8.11.2) with ESMTP id p7FHU6iJ022148 for ; Mon, 15 Aug 2011 19:30:06 +0200 Message-ID: <4E4956DA.1060201@iup.uni-heidelberg.de> Date: Mon, 15 Aug 2011 19:26:50 +0200 From: =?UTF-8?B?U3RlZmFuIFNjaMOkZmVy?= User-Agent: Mozilla/5.0 (Windows; U; Windows NT 6.1; de; rv:1.9.1.8) Gecko/20100227 Thunderbird/3.0.3 MIME-Version: 1.0 To: rsgb_lf_group@blacksheep.org References: <68BE37BD69E54DEE89CEBA8E30E9B94E@PcMinto> <4E47FFE9.10100@iup.uni-heidelberg.de> <3ED8E5422F1F45DBB8186E9D9870AD63@PcMinto> <4E480E02.9020706@iup.uni-heidelberg.de> <938BF599006244949F6CDDB5BA91F347@PcMinto> <4E482FBD.7030402@freenet.de> <4E484183.9090805@iup.uni-heidelberg.de> <4E494A57.90105@freenet.de> In-Reply-To: <4E494A57.90105@freenet.de> X-Spam-Score: 1.4 (+) X-Spam-Report: autolearn=disabled,HTML_MESSAGE=0.001,RATWARE_GECKO_BUILD=1.426 Subject: Re: LF: Ferrite RX antennas Content-Type: multipart/alternative; boundary="------------070108010803040305080700" X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on post.thorcom.com X-Spam-Level: X-Spam-Status: No, hits=0.5 required=5.0 tests=HTML_20_30,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: 0:2:487386368:93952408 X-AOL-SCOLL-URL_COUNT: 0 x-aol-sid: 3039ac1d40cd4e4957ed32a4 X-AOL-IP: 195.171.43.25 X-AOL-SPF: domain : blacksheep.org SPF : none This is a multi-part message in MIME format. --------------070108010803040305080700 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: quoted-printable X-MIME-Autoconverted: from 8bit to quoted-printable by relay2.uni-heidelberg.de id p7FHU5Xn014127 Hello Wolf, Thanks to the link to your nice to read article. I just found it a hour=20 before your mail and already read it ;-) Well, i also prefer the usual configuration instead of that sleeve=20 antenna. Also i have to keep the focus on my actual goal: Making a handy=20 antenna for amateur LF / p operation without a car! And the 16 rods i=20 will get (14 cm long, 8mm diameter) will be best in a 2x7 config. i=20 think. Or do you rather suggest 3x5 or even 4x4? 2x7 is then about 30 cm long which is very fine for a backpack and=20 should be robust enough. I would use the same double side bonding tape, this is very useful to=20 get a first fixed arrangement. Then putting all that in a PVC tube, 2mm=20 thickness and add the turns above the tube. Would you recommend litz wire or standard 0.5 mm enamelled wire? As an E field shield i would use aluminium bonding tape, without making=20 a shutcut turn of course. So the newcomers should not think that this antenna is the best what one=20 can use for LF. Just in that special case of /p i see advantages.=20 Otherwise a well designed loop (+ preamp or a very sensitive RX, if a=20 samll loop is used) or E field antenna such as the PA0RDT should be=20 preferred, as Alan already pointed out. Looking forward to a direct comparison of the DCF39 SNR that can be=20 achieved and to the first amateur signal received with that antenna in /p= ... 73, Stefan/DK7FC Am 15.08.2011 18:33, schrieb wolf_dl4yhf: > Hi Stefan, > The rods were found in Friedrichshafen for a bargain price. I later=20 > discovered (most likely after the topic had been discussed here, or in=20 > the VLF group) that these rods are used for inductive welding=20 > (google("Ferrite Impeder Rod"). Here's a bundle of them: > > http://www.qsl.net/dl4yhf/vlf_rdf/vlf_rdf_loop.html > > They are 20 cm long. > > The most effective use (to "catch the magnetic field from a distant=20 > transmitter") is NOT to connect them 'parallel' in a bundle, but to=20 > connect them in series (up to a certain point). This is much in=20 > contrast to the esoteric sleeve thingy seen somewhere on the web. > > 73, > Wolf . > > > > Am 14.08.2011 23:43, schrieb Stefan Sch=C3=A4fer: >> Wolf, >> >> Which dimensions has your ferrite rod had? >> >> Never thought i will find a source for rods that are longer than 10=20 >> cm but see:=20 >> http://www.box73.de/catalog/product_info.php?products_id=3D1422&osCsid= =3Drqlpfme957i65d7etjil1ntru5 >> >> even an official distributor.. >> >> Any better links? >> >> 73, Stefan/DK7FC >> >> Am 14.08.2011 22:27, schrieb wolf_dl4yhf: >>> Ferrite RX antennas.. been there when 136 kHz started. >>> Not as good as a larger air-core loop, possibly noise caused by the=20 >>> Barkhausen effect or similar effects, nonlinearities, etc. >>> Also beware the ferrite is a semiconductor so you will need some=20 >>> E-field screening, otherwise the ferrite material will couple noise=20 >>> into the windings. But it's not as bad as this may sound; actually I=20 >>> used a ferrite antenna for reception for some years until I=20 >>> discovered I had to disconnect the ...errr... RF counterpoise from=20 >>> the main antenna from the mains "ground", and only use an earthstake=20 >>> during receive, at DF0WD. >>> >>> On the other hand, it's compact, relatively light-weight, and (in a=20 >>> resonant configuration) gives a nice preselector. >>> I remember when I connected a ferrite antenna to a tiny receiver=20 >>> with SA612 "gilbert cell mixer", the first signal I heard was G3KEV=20 >>> calling cq in CW. Q5 in SSB bandwidth. >>> Such a receiver is extremely handy to go /p for reception, and=20 >>> compare different sites. >>> >>> 73, >>> Wolf DL4YHF. >>> >>> >>> Am 14.08.2011 21:43, schrieb Minto Witteveen: >>>> >>>> I haven=E2=80=99t thought about ferrite RX antenna for LF=E2=80=A6.M= y guess is that=20 >>>> it is not going to work =E2=80=93 not without an external antenna co= upled=20 >>>> to the ferrite, and then what=E2=80=99s the point? >>>> DCF77 clocks often have trouble locking indoors or in the=20 >>>> neighborhood of =E2=80=98QRM=E2=80=99 generators like PC=E2=80=99s, = and look what power=20 >>>> DCF77 is using=E2=80=A6 >>>> I could be entirely wrong of course=E2=80=A6 >>>> >>>> 73=E2=80=99 Minto pa3bca >>>> >>>> *From:* Stefan Sch=C3=A4fer >>>> *Sent:* Sunday, August 14, 2011 20:03 >>>> *To:* rsgb_lf_group@blacksheep.org=20 >>>> >>>> *Subject:* Re: LF: Re: 137 grabbers >>>> >>>> BTW what do you think about a ferrite RX antenna for LF? Now i'm=20 >>>> opening an older discussion i expect ;-) >>>> >>>> 73, Stefan/DK7FC >>>> >>>> >>> > --------------070108010803040305080700 Content-Type: text/html; charset=UTF-8 Content-Transfer-Encoding: quoted-printable X-MIME-Autoconverted: from 8bit to quoted-printable by relay2.uni-heidelberg.de id p7FHU5Xn014127 Hello Wolf,

Thanks to the link to your nice to read article. I just found it a hour before your mail and already read it ;-)

Well, i also prefer the usual configuration instead of that sleeve antenna. Also i have to keep the focus on my actual goal: Making a handy antenna for amateur LF / p operation without a car! And the 16 rods i will get (14 cm long, 8mm diameter) will be best in a 2x7 config. i think. Or do you rather suggest 3x5 or even 4x4?
2x7 is then about 30 cm long which is very fine for a backpack and should be robust enough.
I would use the same double side bonding tape, this is very useful to get a first fixed arrangement. Then putting all that in a PVC tube, 2mm thickness and add the turns above the tube.
Would you recommend litz wire or standard 0.5 mm enamelled wire?
As an E field shield i would use aluminium bonding tape, without making a shutcut turn of course.

So the newcomers should not think that this antenna is the best what one can use for LF. Just in that special case of /p i see advantages. Otherwise a well designed loop (+ preamp or a very sensitive RX, if a samll loop is used) or E field antenna such as the PA0RDT should be preferred, as Alan already pointed out.

Looking forward to a direct comparison of the DCF39 SNR that can be achieved and to the first amateur signal received with that antenna in /p...

73, Stefan/DK7FC




Am 15.08.2011 18:33, schrieb wolf_dl4yhf:
Hi Stefan,
The rods were found in Friedrichshafen for a bargain price. I later discovered (most likely after the topic had been discussed here, or in the VLF group) that these rods are used for inductive welding (google("Ferrite Impeder Rod"). Here's a bundle of them:

http://www.= qsl.net/dl4yhf/vlf_rdf/vlf_rdf_loop.html

They are 20 cm long.

The most effective use (to "catch the magnetic field from a distant transmitter") is NOT to connect them 'parallel' in a bundle, but to connect them in series (up to a certain point). This is much in contrast to the esoteric sleeve thingy seen somewhere on the web.

73,
=C2=A0=C2=A0 Wolf .



Am 14.08.2011 23:43, schrieb Stefan Sch=C3=A4fer:
Wolf,

Which dimensions has your ferrite rod had?

Never thought i will find a source for rods that are longer than 10 cm but see: http://www.box73.de/catalog/prod= uct_info.php?products_id=3D1422&osCsid=3Drqlpfme957i65d7etjil1ntru5

even an official distributor..

Any better links?

73, Stefan/DK7FC

Am 14.08.2011 22:27, schrieb wolf_dl4yhf:
Ferrite RX antennas.. been there when 136 kHz started.
Not as good as a larger air-core loop, possibly noise caused by the Barkhausen effect or similar effects, nonlinearities, etc.
Also beware the ferrite is a semiconductor so you will need some E-field screening, otherwise the ferrite material will couple noise into the windings. But it's not as bad as this may sound; actually I used a ferrite antenna for reception for some years until I discovered I had to disconnect the ...errr... RF counterpoise from the main antenna from the mains "ground", and only use an earthstake during receive, at DF0WD.

On the other hand, it's compact, relatively light-weight, and (in a resonant configuration) gives a nice preselector.
I remember when I connected a ferrite antenna to a tiny receiver with SA612 "gilbert cell mixer", the first signal I heard was G3KEV calling cq in CW.=C2=A0 Q5 in SSB bandwidth.
Such a receiver is extremely handy to go /p for reception, and compare different sites.

73,
=C2=A0=C2=A0 Wolf DL4YHF.


Am 14.08.2011 21:43, schrieb Minto Witteveen:


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