Return-Path: Received: (qmail 6953 invoked from network); 1 Feb 2002 10:36:35 -0000 Received: from unknown (HELO murphys-inbound.services.quay.plus.net) (212.159.14.225) by excalibur-qfe1-smtp-plusnet.harl.plus.net with SMTP; 1 Feb 2002 10:36:35 -0000 Received: (qmail 22997 invoked from network); 1 Feb 2002 10:36:33 -0000 Received: from unknown (HELO post.thorcom.com) (212.172.148.70) by murphys.services.quay.plus.net with SMTP; 1 Feb 2002 10:36:33 -0000 Received: from majordom by post.thorcom.com with local (Exim 3.33 #2) id 16Waze-0002cC-00 for rsgb_lf_group-outgoing@blacksheep.org; Fri, 01 Feb 2002 10:32:30 +0000 Received: from irwell.zetnet.co.uk ([194.247.47.48] helo=zetnet.co.uk ident=root) by post.thorcom.com with esmtp (Exim 3.33 #2) id 16Wazd-0002c7-00 for rsgb_lf_group@blacksheep.org; Fri, 01 Feb 2002 10:32:29 +0000 Received: from abc (bts-0012.dialup.zetnet.co.uk [194.247.48.12]) by zetnet.co.uk (8.11.3/8.11.3/Debian 8.11.2-1) with SMTP id g11AVcu29665 for ; Fri, 1 Feb 2002 10:31:39 GMT Message-ID: <000001c1ab0b$742bc4e0$0c30f7c2@zetnet.co.uk> From: "John Rabson" To: rsgb_lf_group@blacksheep.org References: <200201312129.g0VLTF412127@galahad.joust.net> <002d01c1aaab$64bfb760$1700a8c0@home> Subject: Re: LF: Ampliphase Date: Fri, 1 Feb 2002 09:24:22 -0000 MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1; format=flowed Content-Transfer-Encoding: 8bit X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 5.00.2919.6600 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1106 Precedence: bulk Reply-To: rsgb_lf_group@blacksheep.org X-Listname: rsgb_lf_group Sender: ----- Original Message ----- From: "Dave Pick" > ... 4.5KHz cutoff filters that the EBU compliant broadcasters used. What was the specification of those filters? When I was involved in starting up University Radio Essex, a licensed station, in 1970 we were given a specification which required the modulation to be 40dB down at 4.5 kHz from the carrier. We dutifully complied with a filter that would do this with 80% modulation with a sine wave. When the Men from the Ministry did their tests, they used a classical music feed at 30% modulation! The transmitter (a rebuilt KW Vanguard) would have managed that with only a little tailoring of the microphone amplifier. 73 de John Rabson G3PAI PS (off topic) does anyone from that establishment in those days recall a piece of doggerel that started "The chief defect of Shirley Thing"? If you do, please e-mail me direct. Many thanks. J