Return-Path: Received: (qmail 17015 invoked from network); 28 Oct 2002 13:11:09 -0000 Received: from marstons.services.quay.plus.net (212.159.14.223) by mailstore with SMTP; 28 Oct 2002 13:11:09 -0000 Received: (qmail 8951 invoked by uid 10001); 28 Oct 2002 14:15:32 -0000 Received: from post.thorcom.com (193.82.116.70) by marstons.services.quay.plus.net with SMTP; 28 Oct 2002 14:15:32 -0000 Received: from majordom by post.thorcom.com with local (Exim 4.10) id 1869f2-0004CG-00 for rsgb_lf_group-outgoing@blacksheep.org; Mon, 28 Oct 2002 13:10:28 +0000 Received: from [194.73.73.176] (helo=protactinium.btinternet.com) by post.thorcom.com with esmtp (Exim 4.10) id 1869f2-0004C7-00 for rsgb_lf_group@blacksheep.org; Mon, 28 Oct 2002 13:10:28 +0000 Received: from host213-122-129-61.in-addr.btopenworld.com ([213.122.129.61] helo=main) by protactinium.btinternet.com with smtp (Exim 3.22 #8) id 1869f1-0007D7-00 for rsgb_lf_group@blacksheep.org; Mon, 28 Oct 2002 13:10:27 +0000 Message-ID: <000601c27e83$5ef00900$3d817ad5@main> From: "Alan Melia" To: "LF-Group" Date: Mon, 28 Oct 2002 13:09:46 -0000 MIME-Version: 1.0 X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 4.72.3110.5 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1106 Subject: LF: FETs failing Content-Type: text/plain; charset=iso-8859-1; format=flowed Content-Transfer-Encoding: 8bit X-Spam-Status: No, hits=1.0 required=5.0tests=SPAM_PHRASE_00_01,USER_AGENT_OEversion=2.42 X-Spam-Level: * Sender: Precedence: bulk Reply-To: rsgb_lf_group@blacksheep.org X-Listname: rsgb_lf_group Hi All, Jim has raised an interesting point about low current testing which probably applies to BJT RF devices as well in some cases. A lot of these devices consist of several small fets (or smaller BJTs) in parallel on the chip. It is possible to have some of these go open (BJTs suffer breaks in their emitter metallisation due to electro-migration of the contact metal) Breaks in source, or emitter, paralleling track on the chip could mean that the unit could look ok at low currents, but be overloaded when run at full blast. Cheers de Alan G3NYK alan.melia@btinternet.com