Received: from post.thorcom.com (post.thorcom.com [195.171.43.25]) by mtain-da03.r1000.mx.aol.com (Internet Inbound) with ESMTP id B11D338000082; Tue, 2 Aug 2011 16:50:43 -0400 (EDT) Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1QoLuS-0006gD-D3 for rs_out_1@blacksheep.org; Tue, 02 Aug 2011 21:49:52 +0100 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1QoLuR-0006g4-SZ for rsgb_lf_group@blacksheep.org; Tue, 02 Aug 2011 21:49:51 +0100 Received: from mhost02h.leeds.ac.uk ([129.11.77.151]) by relay1.thorcom.net with esmtp (Exim 4.63) (envelope-from ) id 1QoLuP-0007V6-H7 for rsgb_lf_group@blacksheep.org; Tue, 02 Aug 2011 21:49:51 +0100 Received: from APOLLO1.ds.leeds.ac.uk (apollo1.leeds.ac.uk [129.11.5.4]) by mhost02h.leeds.ac.uk (8.14.4/8.14.4) with ESMTP id p72Knh4K022576 (version=TLSv1/SSLv3 cipher=AES128-SHA bits=128 verify=NOT) for ; Tue, 2 Aug 2011 21:49:43 +0100 (BST) Received: from HERMES8.ds.leeds.ac.uk ([fe80::39ce:23e:d0b5:7e24]) by APOLLO1.ds.leeds.ac.uk ([129.11.5.4]) with mapi; Tue, 2 Aug 2011 21:49:43 +0100 From: Chris Trayner To: "rsgb_lf_group@blacksheep.org" Date: Tue, 2 Aug 2011 21:49:42 +0100 Thread-Topic: LF: Poor antennas Thread-Index: AcxRVbSEEBLZhC6NT/qriTloOSdkkA== Message-ID: References: <001601cc5147$61942b50$0401a8c0@xphd97xgq27nyf> <001c01cc5149$c192d630$0401a8c0@xphd97xgq27nyf> In-Reply-To: Accept-Language: en-US, en-GB Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: acceptlanguage: en-US, en-GB MIME-Version: 1.0 X-Spam-Score: 0.0 (/) X-Spam-Report: autolearn=disabled,none Subject: Re: LF: Poor antennas Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: quoted-printable 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=TO_ADDRESS_EQ_REAL 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: 0:2:442841056:93952408 X-AOL-SCOLL-URL_COUNT: 0 x-aol-sid: 3039ac1d404b4e38632315ed X-AOL-IP: 195.171.43.25 X-AOL-SPF: domain : blacksheep.org SPF : none Hi Mal and others, > On 2 August 2011 20:24, mal hamilton wrote: > Warren > I do not have a problem. I can see es hear them all but I am disappointed > how weak my signal looks on some of the EU grabbers compared to yester ye= ars > and some cannot hear me when I call for a QSO. It would be interesting to know if their reports of other Txs have changed = over the same time. In other words, is it a change in their sensitivity (wh= ether due to Ae change, pre-amp characteristics changing or whatever)? > BUT I do not use Probes OR Small loops. I use what one would call normal > LF/MF antennas. On 2011 Aug 2, at 21:33, Gary - G4WGT wrote: > Most grabbers do not use the main antenna, I have only one main antenna f= or LF & MF so the grabber uses an active antenna At LF the background noise is bad compared with HF/VHF/etc., so you can get= away with a smaller antenna. Do the grabber operators do checks like this,= e.g. switch between their active ant and a larger main ant and see if the = SNR (as against the signal level) changes? If it doesn't, then their smalle= r ant is good enough.=20 Perhaps some of the grabber operators would like to reply with their hints = and kinks - personally I'm ignorant of how they run these things. 73, Chris G4OKW ----------------------- Dr Chris Trayner School of Electronic & Electrical Engineering, The University of Leeds, Leeds LS2 9JT, United Kingdom Tel: +44 113 34 32053 Fax: +44 113 34 32032