Received: from post.thorcom.com (post.thorcom.com [195.171.43.25]) by mtain-dd05.r1000.mx.aol.com (Internet Inbound) with ESMTP id AEBBB38000114; Sun, 14 Aug 2011 16:28:46 -0400 (EDT) Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1QshHf-0001T2-9L for rs_out_1@blacksheep.org; Sun, 14 Aug 2011 21:27:47 +0100 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1QshHe-0001St-JD for rsgb_lf_group@blacksheep.org; Sun, 14 Aug 2011 21:27:46 +0100 Received: from mout4.freenet.de ([195.4.92.94]) by relay1.thorcom.net with esmtp (Exim 4.63) (envelope-from ) id 1QshHd-00033y-3B for rsgb_lf_group@blacksheep.org; Sun, 14 Aug 2011 21:27:46 +0100 Received: from [195.4.92.17] (helo=7.mx.freenet.de) by mout4.freenet.de with esmtpa (ID dl4yhf@freenet.de) (port 25) (Exim 4.76 #5) id 1QshHb-00074x-Ob for rsgb_lf_group@blacksheep.org; Sun, 14 Aug 2011 22:27:43 +0200 Received: from blfd-4d086788.pool.mediaways.net ([77.8.103.136]:3794 helo=[192.168.0.101]) by 7.mx.freenet.de with esmtpsa (ID dl4yhf@freenet.de) (TLSv1:CAMELLIA256-SHA:256) (port 465) (Exim 4.76 #5) id 1QshHb-0000gG-9x for rsgb_lf_group@blacksheep.org; Sun, 14 Aug 2011 22:27:43 +0200 Message-ID: <4E482FBD.7030402@freenet.de> Date: Sun, 14 Aug 2011 22:27:41 +0200 From: wolf_dl4yhf User-Agent: Mozilla/5.0 (Windows NT 5.1; rv:5.0) Gecko/20110624 Thunderbird/5.0 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> In-Reply-To: <938BF599006244949F6CDDB5BA91F347@PcMinto> X-Spam-Score: 1.4 (+) X-Spam-Report: autolearn=disabled,HTML_MESSAGE=0.001,RATWARE_GECKO_BUILD=1.426 Subject: Re: LF: Re: 137 grabbers Content-Type: multipart/alternative; boundary="------------090200050404050708090301" 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: 0:2:456619040:93952408 X-AOL-SCOLL-URL_COUNT: 0 x-aol-sid: 3039ac1d40914e482ffe3543 X-AOL-IP: 195.171.43.25 X-AOL-SPF: domain : blacksheep.org SPF : none This is a multi-part message in MIME format. --------------090200050404050708090301 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit 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. Q5 in SSB bandwidth. Such a receiver is extremely handy to go /p for reception, and compare different sites. 73, Wolf DL4YHF. Am 14.08.2011 21:43, schrieb Minto Witteveen: > > I haven’t thought about ferrite RX antenna for LF….My guess is that it > is not going to work – not without an external antenna coupled to the > ferrite, and then what’s the point? > DCF77 clocks often have trouble locking indoors or in the neighborhood > of ‘QRM’ generators like PC’s, and look what power DCF77 is using… > I could be entirely wrong of course… > > 73’ Minto pa3bca > > *From:* Stefan Schäfer > *Sent:* Sunday, August 14, 2011 20:03 > *To:* rsgb_lf_group@blacksheep.org > *Subject:* Re: LF: Re: 137 grabbers > > BTW what do you think about a ferrite RX antenna for LF? Now i'm > opening an older discussion i expect ;-) > > 73, Stefan/DK7FC > > --------------090200050404050708090301 Content-Type: text/html; charset=UTF-8 Content-Transfer-Encoding: 8bit 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.  Q5 in SSB bandwidth.
Such a receiver is extremely handy to go /p for reception, and compare different sites.

73,
   Wolf DL4YHF.


Am 14.08.2011 21:43, schrieb Minto Witteveen:

I haven’t thought about ferrite RX antenna for LF….My guess is that it is not going to work – not without an external antenna coupled to the ferrite, and then what’s the point?
DCF77 clocks often have trouble locking indoors or in the neighborhood of ‘QRM’ generators like PC’s, and look what power DCF77 is using…
I could be entirely wrong of course…

73’ Minto pa3bca

 
Sent: Sunday, August 14, 2011 20:03
Subject: Re: LF: Re: 137 grabbers
 
<snip>
BTW what do you think about a ferrite RX antenna for LF? Now i'm opening an older discussion i expect ;-)

73, Stefan/DK7FC



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