Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on lipkowski.org X-Spam-Level: X-Spam-Status: No, score=-0.7 required=5.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, RCVD_IN_DNSWL_MED,SPF_PASS,SUBJ_ALL_CAPS autolearn=ham autolearn_force=no version=3.4.0 X-Spam-DCC: : mailn 1480; Body=2 Fuz1=2 Fuz2=2 Received: from post.thorcom.com (post.thorcom.com [195.171.43.25]) by lipkowski.org (8.14.4/8.14.4/Debian-8+deb8u1) with ESMTP id v3DE3mEB013866 for ; Thu, 13 Apr 2017 16:03:49 +0200 Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1cyfHf-0003HH-TU for rs_out_1@blacksheep.org; Thu, 13 Apr 2017 14:59:39 +0100 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1cyfHf-0003H8-FS for rsgb_lf_group@blacksheep.org; Thu, 13 Apr 2017 14:59:39 +0100 Received: from mout02.posteo.de ([185.67.36.66]) by relay1.thorcom.net with esmtps (TLSv1.2:ECDHE-RSA-AES256-GCM-SHA384:256) (Exim 4.89) (envelope-from ) id 1cyfHc-0005sV-Si for rsgb_lf_group@blacksheep.org; Thu, 13 Apr 2017 14:59:38 +0100 Received: from submission (posteo.de [89.146.220.130]) by mout02.posteo.de (Postfix) with ESMTPS id CD27C20BD4 for ; Thu, 13 Apr 2017 15:59:35 +0200 (CEST) Received: from customer (localhost [127.0.0.1]) by submission (posteo.de) with ESMTPSA id 3w3j8R1gxHz109t for ; Thu, 13 Apr 2017 15:59:35 +0200 (CEST) Message-ID: <58EF8446.9020409@posteo.de> Date: Thu, 13 Apr 2017 15:59:34 +0200 From: DK7FC User-Agent: Mozilla/5.0 (Windows; U; Windows NT 6.1; de; rv:1.9.1.8) Gecko/20100227 Thunderbird/3.0.3 MIME-Version: 1.0 To: rsgb_lf_group@blacksheep.org References: <58EA2389.9070107@posteo.de> <519a2968-f0e0-e779-a1e9-c3e1e0085ba8@psk31.plus.com> <58EB9AA6.1010804@posteo.de> In-Reply-To: X-Scan-Signature: 7001055fa59a9c23b9831ea6d317a074 Subject: Re: VLF: DFCW-6000 Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit 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-Scanned-By: MIMEDefang 2.75 Status: O X-Status: X-Keywords: X-UID: 11260 ...you may ask the neighbours to place a wire antenna close to their house, picking up strong E fields :-) These signals fed to a JFET source follower, then use a transformer somewhere in your RX chain and add some turns on this transformer (0/180 deg switchable) for the compensation from the noise pick up antenna. For a single strong noise source it could help. Maybe a mains HV overhead line travelling nearby. With a small probe close to the noise source it could work just to pick up the noise and only little of the wanted signal. The software hum filters perform not so perfectly as it looks because the sharp notches can lower the performance of a noise blanker... The method is rarely used so it seems it doesn't work well in most situations. 73, Stefan Am 13.04.2017 15:43, schrieb g3zjo: > On 13/04/2017 08:27, John Bache G7JMZ wrote: >> Blue sky idea: > > Hi John > > Good thinking. > > I think the hum filters used in SpectrumLab specificity the Paul > Nicholson ones work in that manner. A lot of the mains borne > interference is from consumer gadgets with switch mode supplies, > causing bands of QRM right up to 7.5kHz plus, worse at the moment due > to school holidays I suspect. > > 73 Eddie G3ZJO >