Return-Path: Received: (qmail 32683 invoked from network); 2 May 2003 20:31:59 -0000 Received: from netmail02.services.quay.plus.net (212.159.14.221) by mailstore with SMTP; 2 May 2003 20:31:59 -0000 Content-Transfer-Encoding: 8bit Received: (qmail 1689 invoked by uid 10001); 2 May 2003 20:31:59 -0000 X-Priority: 3 X-MSMail-Priority: Normal Received: from post.thorcom.com (193.82.116.70) by netmail02.services.quay.plus.net with SMTP; 2 May 2003 20:31:59 -0000 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1106 X-SQ: A Received: from majordom by post.thorcom.com with local (Exim 4.14) id 19BhBn-0004wK-MD for rsgb_lf_group-outgoing@blacksheep.org; Fri, 02 May 2003 21:31:27 +0100 Received: from [212.125.75.12] (helo=mail4.messagelabs.com) by post.thorcom.com with smtp (Exim 4.14) id 19BhBi-0004wB-Le for rsgb_lf_group@blacksheep.org; Fri, 02 May 2003 21:31:22 +0100 X-VirusChecked: Checked X-Env-Sender: William.Ashlock@bocedwards.com X-Msg-Ref: server-2.tower-4.messagelabs.com!1051907460!45755 Received: (qmail 25925 invoked from network); 2 May 2003 20:31:00 -0000 Received: from ukfw1.ge.boc.com (193.131.2.157) by server-2.tower-4.messagelabs.com with SMTP; 2 May 2003 20:31:00 -0000 Received: from exc-cra03 ([160.100.160.136]) by ukfw1.ge.boc.com; Fri, 02 May 2003 21:32:05 +0100 (BST) Received: from exc_wil04.edwards.boc.com ([162.118.144.226]) by exc_cra03.edwards.boc.com with SMTP (Microsoft Exchange Internet Mail Service Version 5.5.2653.13) id J31XFV0M; Fri, 2 May 2003 21:36:01 +0100 Received: by EXC_WIL04 with Internet Mail Service (5.5.2653.19) id <2RDJ4MAP>; Fri, 2 May 2003 16:31:44 -0400 Message-ID: From: "Ashlock,William" To: rsgb_lf_group@blacksheep.org Date: Fri, 2 May 2003 16:31:42 -0400 MIME-Version: 1.0 X-Mailer: Internet Mail Service (5.5.2653.19) Subject: RE: LF: Mains Cable and other transmission lines Content-Type: text/plain; charset=iso-8859-1; format=flowed X-Spam-Status: No, hits=0.0 required=5.0tests=noneversion=2.53 X-Spam-Checker-Version: SpamAssassin 2.53 (1.174.2.15-2003-03-30-exp) X-SA-Exim-Scanned: Yes Sender: Precedence: bulk Reply-To: rsgb_lf_group@blacksheep.org X-Listname: rsgb_lf_group X-SA-Exim-Rcpt-To: rsgb_lf_group-outgoing@blacksheep.org X-SA-Exim-Scanned: No; SAEximRunCond expanded to false John A, >With the proposed 100 watt transmitter output limit here in the U.S., we can >be a little more conservative with audio amplifiers used as transmitter >PA's. I have been playing with a nominal "8 ohm" amplifier (actually two "4 >ohm" amps in bridging configuration), and using a 1:2 transformer that >presents 12.5 ohms to the PA when terminated in 50 ohms. As noted in the LF >Handbook, the output impedance of these amps can rise with frequency, and >there is plenty of power available with the 100 watt restriction. I tend to be in agreement with Mr. Mal on this subject. (Mark this date) Most amplifiers designed for audio use are slew rate limited when it comes to a full bore 137K sine wave because of the output devices. These amps usually check out OK on the bench with dummy loads but under 'real life' conditions there's little margin for transients - where the transient power (current times voltage) seen by the output devices can unknowingly be many times the maximum ratings. Bill A _____________________________________________________________________ This e-mail has been scanned for viruses by the WorldCom Internet Managed Scanning Service - powered by MessageLabs. For further information visit http://www.worldcom.com