Return-Path: Received: from rly-mb02.mx.aol.com (rly-mb02.mail.aol.com [172.21.131.155]) by air-mb08.mail.aol.com (v123.4) with ESMTP id MAILINMB084-cee4a301f478d; Wed, 10 Jun 2009 17:02:23 -0400 Received: from post.thorcom.com (post.thorcom.com [193.82.116.20]) by rly-mb02.mx.aol.com (v123.4) with ESMTP id MAILRELAYINMB022-cee4a301f478d; Wed, 10 Jun 2009 17:02:02 -0400 Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1MEUuj-00076B-FQ for rs_out_1@blacksheep.org; Wed, 10 Jun 2009 22:00:53 +0100 Received: from [193.82.116.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1MEUuj-000762-3A for rsgb_lf_group@blacksheep.org; Wed, 10 Jun 2009 22:00:53 +0100 Received: from smtp817.mail.ird.yahoo.com ([77.238.189.17]) by relay1.thorcom.net with smtp (Exim 4.63) (envelope-from ) id 1MEUue-0008At-Ke for rsgb_lf_group@blacksheep.org; Wed, 10 Jun 2009 22:00:52 +0100 Received: (qmail 49728 invoked from network); 10 Jun 2009 21:00:43 -0000 DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws; s=s1024; d=btopenworld.com; h=Received:X-Yahoo-SMTP:X-YMail-OSG:X-Yahoo-Newman-Property:Message-ID:From:To:References:In-Reply-To:Subject:Date:MIME-Version:Content-Type:Content-Transfer-Encoding:X-Priority:X-MSMail-Priority:X-Mailer:X-MIMEOLE; b=IZoUIN0HgKEUy1cthIlyDMNd2P/Gxf2CmQmJaoBhCGpQRckovf5K4QyokVmajYINWZEITfy/+QFkljWGIsMcQt5vrP/8moxs/Dp8LxoLOgCH1fOC8x/f43LzYqNoyHq6RrV0igcfQd5lPdB4RttvH2+MNQ+M/Mj7yNHZEbZB7lM= ; Received: from unknown (HELO JimPC) (james.moritz@86.177.185.193 with login) by smtp817.mail.ird.yahoo.com with SMTP; 10 Jun 2009 21:00:43 -0000 X-Yahoo-SMTP: qKIhhNCswBB2TTHr2BORWcGGR2mpopxhCcunGIxpCKQYiG07Q7UOhNo- X-YMail-OSG: _PCqkKoVM1l8XqO_JgYyH1HQgIOAwz8tkZjZ8zd8jeg4zoA0SZJ1OqlYZ2QrZ3jWvdRbxbn5YrjR4kWVus3gjTbeA63VHzEDSNXOKWZH4kWCGJdz50u2OTA2.PsbhsNNDcasxT4lxn1GrdE9XG7uo3MDMjxjVPebbE.wDjW7Puiq9HidnTfbJB8ZMc_VIFSRypYThhyflP1pK6ohMBEH_7UfaaM_5oo5uwJwZmh8PS9fFF2Exy2MRa3O9SKqoUBPpxCphsgmLugL6OpVlaJO2Mbh7CritHnHPy.vFvLS5mrMhHMFmMYkhmfGyMRIn8juJ2GLyDmLDLcz5nW7_FJH X-Yahoo-Newman-Property: ymail-3 Message-ID: From: "James Moritz" To: References: In-Reply-To: Date: Wed, 10 Jun 2009 22:00:42 +0100 MIME-Version: 1.0 X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Windows Mail 6.0.6001.18000 X-MIMEOLE: Produced By Microsoft MimeOLE V6.0.6001.18049 X-Karma: unknown: DomainKey-Status: good (testing) X-Spam-Score: 0.0 (/) X-Spam-Report: autolearn=disabled,none Subject: Re: LF: Re Welbrook Loops Content-Type: text/plain; format=flowed; charset="iso-8859-1"; reply-type=original 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=0.1 required=5.0 tests=MISSING_OUTLOOK_NAME 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-IP: 193.82.116.20 Dear Tim, LF Group, I tried some expeiments with measuring loop antennas at LF and MF a while back - changing the height above ground from 0 - 10m made virtually no difference. The only thing that made a lot of difference to signal levels is if the loop is very close to big metal objects, but even then the difference is only minor unless the metal thing is big compared to the loop, and within a loop diameter, say. I would agree with G3YXM about overloading - if you have an oscilloscope, it is worth connecting it to the loop output to see if any huge signals are present. I have used elliptic low pass filters here to reduce the signal level from the local medium wave broadcast stations to a reasonable level. Cheers, Jim Moritz 73 de M0BMU ----- Original Message ----- From: "Trevor Smithers" To: Cc: Sent: Wednesday, June 10, 2009 11:40 AM Subject: Re: LF: Re Welbrook Loops >I use a 1530 as well, its mounted on a rotator about 2ft above ground level >on a Barenco > socket/spike. Works well 80m down to 500khz but being so close to the > ground its a bit deaf > above 80m as you would expect. My understanding is that for hf it should > me mounted high up but > for lf its better low down near the ground. > > A rotator isn't really necessary as the beamwidth is quite broad but where > I do find it useful is > nulling out the local qrm, switch modes etc. >