Return-Path: Received: (qmail 28816 invoked from network); 11 May 2001 06:37:36 -0000 Received: from unknown (HELO murphys-inbound.servers.plus.net) (212.159.14.225) by excalibur.plus.net with SMTP; 11 May 2001 06:37:36 -0000 Received: (qmail 17360 invoked from network); 11 May 2001 06:37:02 -0000 Content-Transfer-Encoding: 8bit Received: from unknown (HELO post.thorcom.com) (212.172.148.70) by murphys with SMTP; 11 May 2001 06:37:02 -0000 X-Priority: 3 X-MSMail-Priority: Normal Received: from majordom by post.thorcom.com with local (Exim 3.16 #2) id 14y6Ob-00061S-00 for rsgb_lf_group-outgoing@blacksheep.org; Fri, 11 May 2001 07:27:25 +0100 Received: from fm215.facility.pipex.com ([194.131.104.225]) by post.thorcom.com with esmtp (Exim 3.16 #2) id 14y6OL-00061K-00 for rsgb_lf_group@blacksheep.org; Fri, 11 May 2001 07:27:11 +0100 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1106 Received: from 233.pncl.co.uk (181.235.35.212.in-addr.arpa.ip-pool.cix.co.uk [212.35.235.181]) by fm215.facility.pipex.com (8.9.3/8.9.3) with ESMTP id HAA15047 for ; Fri, 11 May 2001 07:18:43 +0100 (BST) Message-ID: <5.0.2.1.2.20010511072400.00a18600@mail.pncl.co.uk> X-Sender: blanch@mail.pncl.co.uk (Unverified) X-Mailer: QUALCOMM Windows Eudora Version 5.0.2 Date: Fri, 11 May 2001 07:25:26 +0100 To: rsgb_lf_group@blacksheep.org From: "Walter Blanchard" Subject: RE: LF: harmonics / LF antenna In-reply-to: <65AECDF1F89AD411900400508BFC869F9C0496@pdw-mail-1.dera.gov .uk> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii; format=flowed Precedence: bulk Reply-To: rsgb_lf_group@blacksheep.org X-Listname: rsgb_lf_group Sender: At 14:59 10/05/01 Thursday, Andy wrote: >The local Non Directional Beacon here, EAS at Southampton Airport on >391.5kHz, puts out strong odd order harmonics. The fifth harmonic on >1957.5 actually caused QRM once. The third harmonic is masked by a >local broadcast station at my QTH, but would probably be a problem to >listeners nearer the airport. > >Does anyone know the internal design of these NDBs- wouldn't surprise me >if they drive a squarewave to their (what looks to be rather small) >antenna. In which case how do they generate the AM ? Maybe they're still using a T1154 - they were notorious for this problem! Walter G3JKV.