Envelope-to: dave@picks.force9.co.uk Delivery-date: Fri, 10 Jun 2005 14:02:53 +0100 Received: by pih-mxcore11.plus.net with spam-scanned (PlusNet MXCore v2.00) id 1Dgj9x-0001Ld-0Y for dave@picks.force9.co.uk; Fri, 10 Jun 2005 14:02:53 +0100 Received: from post.thorcom.com ([193.82.116.20]) by pih-mxcore11.plus.net with esmtp (PlusNet MXCore v2.00) id 1Dgj9w-0001LI-Qa for dave@picks.force9.co.uk; Fri, 10 Jun 2005 14:02:52 +0100 Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1Dgj9M-0001Xc-OV for rs_out_1@blacksheep.org; Fri, 10 Jun 2005 14:02:16 +0100 Received: from [193.82.59.130] (helo=relay2.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1Dgj9M-0001XT-5d for rsgb_lf_group@blacksheep.org; Fri, 10 Jun 2005 14:02:16 +0100 Received: from mk-smarthost-3.mail.uk.tiscali.com ([212.74.114.39]) by relay2.thorcom.net with esmtp (Exim 4.51) id 1DgjG5-0002zm-2c for rsgb_lf_group@blacksheep.org; Fri, 10 Jun 2005 14:09:14 +0100 Received: from dsl-80-43-36-216.access.as9105.com ([80.43.36.216]:1084 helo=tcs01) by mk-smarthost-3.mail.uk.tiscali.com with smtp (Exim 4.30) id 1Dgj9F-00037d-1p for rsgb_lf_group@blacksheep.org; Fri, 10 Jun 2005 13:02:09 +0000 From: "Gary - G4WGT" To: rsgb_lf_group@blacksheep.org Date: Fri, 10 Jun 2005 14:01:10 +0100 Message-ID: MIME-Version: 1.0 X-Priority: 3 (Normal) X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook IMO, Build 9.0.2416 (9.0.2910.0) X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.2180 Importance: Normal In-Reply-To: <000101c56da7$42836300$3daee150@g1l5x3> Subject: LF: RE: Unwanted LF radiation Content-Type: text/plain; charset=iso-8859-1; format=flowed Content-Transfer-Encoding: 8bit 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-PN-SpamFiltered: by PlusNet MXCore (v2.00) Hi Howard, In response I can only say that I am Tiscali Broadband on a BT line whilst activly receiving signals mainly on 136KHz but often tuning 30 KHZ up to 500 KHz & I have not come accross anything like you have described. I can only asume that the problem you have there is not generated by broadband signals on BT lines. I hope this is of some help. Regards, Gary - G4WGT - IO83qp Web : http://myweb.tiscali.co.uk/wgtaylor -----Original Message----- From: owner-rsgb_lf_group@blacksheep.org [mailto:owner-rsgb_lf_group@blacksheep.org]On Behalf Of Howard Aspinall Sent: 10 June 2005 11:27 To: rsgb_lf_group@blacksheep.org Subject: LF: Unwanted LF radiation This might be just a bit off the beaten track for the reflector, despite being LF orientated, but I wonder if anyone has any useful observations or information they might pass on. Whilst tracking down some noise interference problems, I discovered sizeable amounts of wideband RF between 75 and 130 KHz. This manifests itself as "smooth" noise. It extends outside these frequency parameters well into long/medium waveband, and is radiating from the overhead BT telephone drop line. Broadband internet RF seems the most likely culprit (there being a null between 130 and 140 KHz), but we do not have any broadband facility here. An HP spectrum analyser close coupled to the line (common mode) shows this signal level to reach at least 5 mV around 100 KHz. Tests on BT lines in other areas where broadband is also not installed show no RF present other than broadcast stations etc. Can anyone say if such common mode RF levels on BT lines can be typical, or might be expected where no broadband facilities are connected? Are levels I am finding here regarded as acceptable? And does anyone know of any regulations, codes of practice or technical standards on the subject? Howard G3RXH