Return-Path: Received: from post.thorcom.com (post.thorcom.com [195.171.43.25]) by klubnl.pl (8.14.4/8.14.4/Debian-8+deb8u2) with ESMTP id w1CGdsC2011885 for ; Mon, 12 Feb 2018 17:39:55 +0100 Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1elGvw-0006Av-1B for rs_out_1@blacksheep.org; Mon, 12 Feb 2018 16:26:24 +0000 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1elGvt-0006Am-OW for rsgb_lf_group@blacksheep.org; Mon, 12 Feb 2018 16:26:21 +0000 Received: from know-smtprelay-omc-4.server.virginmedia.net ([80.0.253.68]) by relay1.thorcom.net with esmtps (TLSv1.2:ECDHE-RSA-AES256-GCM-SHA384:256) (Exim 4.89) (envelope-from ) id 1elGvp-0007ij-LY for rsgb_lf_group@blacksheep.org; Mon, 12 Feb 2018 16:26:20 +0000 Received: from [192.168.1.2] ([82.31.180.39]) by cmsmtp with ESMTP id lGvle0QucHORZlGvmebuki; Mon, 12 Feb 2018 16:26:14 +0000 X-DKIM-Result: Domain=ntlworld.com Result=Signature OK X-Originating-IP: [82.31.180.39] X-Authenticated-User: X-Spam: 0 X-Authority: v=2.3 cv=BpyzP7f5 c=1 sm=1 tr=0 a=sVtWtjZQCe36+A3m2HleAg==:117 a=sVtWtjZQCe36+A3m2HleAg==:17 a=kj9zAlcOel0A:10 a=x7bEGLp0ZPQA:10 a=bM0a0dLEAAAA:8 a=QJn2qEQXAAAA:8 a=pGLkceISAAAA:8 a=NulvdfPeWDUH2sEekQ4A:9 a=CjuIK1q_8ugA:10 a=90WxlT6We0YA:10 a=cBLBxAf0BhUA:10 a=hcv4JhYustDcWLqX2U40:22 a=NZzwe_VETcrGNayP8orM:22 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ntlworld.com; s=meg.feb2017; t=1518452774; bh=VMZU2taI74OHuWJ4tBa6ILFG6vZB8umb/bvi8ZiY5gs=; h=From:To:Date:Subject:Reply-to:CC:In-reply-to:References; b=roc7u3RYDEmNaEnW5C+OD/Q9SLJMOio34wBQmrXFCcomP4y3uh5b/Yw5uM3DGzwVg +xcXDOT4KszSmdaVlxYorha2ZG3ihrSlLlSjRbpXKDYyDLJMLEOSoUgaGGgqVtxQ/r CYx7KLks3kzrZ4kHkLHV9ZxtF+Hxd2gel4zCw5iFfqI3Htbv9xl7pewcrc8jhCZktr eDGlXOVWuIsuBsDEnUl4V+aUYMkaJML23W1HS71Itst5d4Qp1nCfyrIvz3UsTMwY5w 5QV2yGJFTLbRNLR5wxQWwsU8IITqpS4p43bujPn1c4QtUj4ulnLNglRk8HgDdHthxi yHGx2sv0lk3Lg== From: "Mike Dennison" To: rsgb_lf_group@blacksheep.org Date: Mon, 12 Feb 2018 16:26:13 -0000 MIME-Version: 1.0 CC: dead.fets@gmail.com Message-ID: <5A81C025.13685.51C8EA38@mike.dennison.ntlworld.com> In-reply-to: <1125097296.20180212141115@gmail.com> References: <1125097296.20180212141115@gmail.com> X-mailer: Pegasus Mail for Windows (4.72.572) Content-description: Mail message body X-CMAE-Envelope: MS4wfNxEEEhMoyysuUvm+7wNYsMn8+A9mIvChEhi4aH6ovodze8L3t27BnLi0YVq4Y/YJ1OhiGlkbcl2DEIgAZC42s73xpuyMVyiC/X8j+88qHl7xUEl0qIF NqYSSPRt+AKTL1h59q6RhhfzjuBLE0/bfvM4ZMM7r5KTfligsXVmaGkhGpN960dTEu3Ah69tIY4Ol0O5qzb9vT8w3E5UBD8ctone7RQz2/XGv2X0k9mylrg9 X-Spam-Score: 0.0 (/) X-Spam-Report: Spam detection software, running on the system "relay1.thorcom.net", has NOT identified this incoming email as spam. The original message has been attached to this so you can view it or label similar future email. If you have any questions, see the administrator of that system for details. Content preview: Chris, It looks like you have a broadcast station where it shouldn't be (at 132.65kHz) and several other spurious stations in that area, so you may well have unwanted signals within the 136kHz band, especially at night (your recording seems to have been done during the middle of the day). You might improve things by by-passing the pre-amp. It would do no harm just by experimenting with an attenuator but why attenuate and amplify at the same time unless the preamp also provides another function such as matching? It seems the only front-end selectivity on that receiver is a narrow bandpass so you would really benefit from some additional wider filtering, eg an LPF with a cut-off just below the LW BC band. [...] Content analysis details: (0.0 points, 5.0 required) pts rule name description ---- ---------------------- -------------------------------------------------- 0.0 T_DKIM_INVALID DKIM-Signature header exists but is not valid X-Scan-Signature: 3b8620872b19e25fb6f4dfaf1256edc3 Subject: Re: LF: Do I need an attenuator on LF RX?? 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 Chris, It looks like you have a broadcast station where it shouldn't be (at 132.65kHz) and several other spurious stations in that area, so you may well have unwanted signals within the 136kHz band, especially at night (your recording seems to have been done during the middle of the day). You might improve things by by-passing the pre-amp. It would do no harm just by experimenting with an attenuator but why attenuate and amplify at the same time unless the preamp also provides another function such as matching? It seems the only front-end selectivity on that receiver is a narrow bandpass so you would really benefit from some additional wider filtering, eg an LPF with a cut-off just below the LW BC band. Mike, G3XDV ========== On 12 Feb 2018 at 14:11, Chris Wilson wrote: > > > Hello LF'ers, > > I would like to know if the experts here think I need an antenna > attenuator on 136kHz? I am using in this capture a little IDC > receiver: > > http://icas.to/lineup/idc-136-kit-eng.htm > > but see the same with a Softrock LF. I am unsure if the antenna is > overloading the RX, it's a big file at around 14 megs, but I guess > most people, unlike me in the sticks, have broadband :) > > > Thanks. > > http://www.gatesgarth.com/Untitled26.mp4 > > -- > Best regards, > Chris mailto:dead.fets@gmail.com > >