Received: from post.thorcom.com (post.thorcom.com [195.171.43.25]) by mtain-mg03.r1000.mx.aol.com (Internet Inbound) with ESMTP id A1CA238000095; Mon, 12 Sep 2011 08:37:48 -0400 (EDT) Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1R35kZ-00051W-HE for rs_out_1@blacksheep.org; Mon, 12 Sep 2011 13:36:35 +0100 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1R35kZ-00051N-4M for rsgb_lf_group@blacksheep.org; Mon, 12 Sep 2011 13:36:35 +0100 Received: from mtaout02-winn.ispmail.ntl.com ([81.103.221.48]) by relay1.thorcom.net with esmtp (Exim 4.63) (envelope-from ) id 1R35kY-0000W0-NE for rsgb_lf_group@blacksheep.org; Mon, 12 Sep 2011 13:36:35 +0100 Received: from aamtaout03-winn.ispmail.ntl.com ([81.103.221.35]) by mtaout02-winn.ispmail.ntl.com (InterMail vM.7.08.04.00 201-2186-134-20080326) with ESMTP id <20110912123626.MZAU17426.mtaout02-winn.ispmail.ntl.com@aamtaout03-winn.ispmail.ntl.com> for ; Mon, 12 Sep 2011 13:36:26 +0100 Received: from [192.168.2.2] (really [82.5.252.56]) by aamtaout03-winn.ispmail.ntl.com (InterMail vG.3.00.04.00 201-2196-133-20080908) with ESMTP id <20110912123626.ZFOE24017.aamtaout03-winn.ispmail.ntl.com@[192.168.2.2]> for ; Mon, 12 Sep 2011 13:36:26 +0100 From: "Mike Dennison" To: rsgb_lf_group@blacksheep.org Date: Mon, 12 Sep 2011 13:36:20 +0100 MIME-Version: 1.0 Message-ID: <4E6E0AD4.4838.465714@mike.dennison.ntlworld.com> X-mailer: Pegasus Mail for Windows (4.41) Content-description: Mail message body X-Cloudmark-Analysis: v=1.1 cv=JvdXmxIgLJv2/GthKqHpGJEEHukvLcvELVXUanXFreg= c=1 sm=0 a=uObrxnre4hsA:10 a=9YlaCzn6_68A:10 a=kj9zAlcOel0A:10 a=sZFixhULmtQx0BC5YvkA:9 a=BNA7-4X-PJC7ACfSJtcA:7 a=CjuIK1q_8ugA:10 a=HpAAvcLHHh0Zw7uRqdWCyQ==:117 X-Spam-Score: 0.0 (/) X-Spam-Report: autolearn=disabled,none Subject: LF: Ferrite antennas Content-type: text/plain; charset=US-ASCII Content-transfer-encoding: 7BIT X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on post.thorcom.com X-Spam-Level: X-Spam-Status: No, hits=0.0 required=5.0 tests=none 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: 0:2:366514016:93952408 X-AOL-SCOLL-URL_COUNT: 0 x-aol-sid: 3039ac1d60cb4e6dfd1c23b2 X-AOL-IP: 195.171.43.25 X-AOL-SPF: domain : blacksheep.org SPF : none I have been following the discussion on ferrite receiving antennas - due to work pressures I am a few weeks behind in reading the mail. The use of this type of antenna for LF amateur radio is not new. I used it successfully as a portable antenna on the old 73kHz band several years ago. I used the existing winding (LItz) an ordinary long-wave broadcast radio antenna. The rod was about 150mm long. The coil, tuned with a large fixed C and a variable C, formed the drain load of a 2N3819, with the output taken from the source. The selectivity was very high indeed (essential to reduce the huge commercial signal on the 73kHz band) and sensitivity was adequate to overcome the noise level of my very sensitive Datong LF converter. The interesting thing was that Peter, G3LDO, tried to replicate this and had poorer results, perhaps indicating that not all long wave radios had ferrite that worked at 73kHz. Mike, G3XDV ==========