Return-Path: Received: (qmail 68556 invoked from network); 30 Jan 2004 16:38:01 -0000 Received: from unknown (HELO ptb-mxscan02.plus.net) (212.159.14.236) by ptb-mailstore02.plus.net with SMTP; 30 Jan 2004 16:38:01 -0000 Received: (qmail 40804 invoked from network); 30 Jan 2004 16:38:01 -0000 X-Filtered-by: Plusnet (hmail v1.01) X-Spam-detection-level: 11 X-Priority: 3 X-MSMail-Priority: Normal Received: from ptb-mxcore02.plus.net (212.159.14.216) by ptb-mxscan02.plus.net with SMTP; 30 Jan 2004 16:37:59 -0000 Received: from post.thorcom.com ([193.82.116.20]) by ptb-mxcore02.plus.net with esmtp (Exim) id 1AmbeZ-000ATp-Jz for dave@picks.force9.co.uk; Fri, 30 Jan 2004 16:37:59 +0000 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1106 X-Fake-Domain: majordom Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1Ambdm-0002ko-BZ for rs_out@blacksheep.org; Fri, 30 Jan 2004 16:37:10 +0000 Received: from [194.25.134.18] (helo=mailout04.sul.t-online.com) by post.thorcom.com with esmtp (Exim 4.14) id 1Ambdl-0002kf-PF for rsgb_lf_group@blacksheep.org; Fri, 30 Jan 2004 16:37:10 +0000 X-Fake-Domain: fwd03.aul.t-online.de Received: from fwd03.aul.t-online.de by mailout04.sul.t-online.com with smtp id 1Ambdk-0003X2-01; Fri, 30 Jan 2004 17:37:08 +0100 X-Fake-Domain: (Gz77z8Z-Ze1UDHwW8vG9TOkqFY1lAra1k3Wjsi4fr0X7X5BN0S9w8m@[62.224.51.7]) Received: from (Gz77z8Z-Ze1UDHwW8vG9TOkqFY1lAra1k3Wjsi4fr0X7X5BN0S9w8m@[62.224.51.7]) by fwd03.sul.t-online.com with smtp id 1AmbdK-1Oy81Z0; Fri, 30 Jan 2004 17:36:42 +0100 From: "jannsen" <0482183881-0001@t-online.de> To: rsgb_lf_group@blacksheep.org References: <6.0.1.1.2.20040129133740.036bcc40@POP3.freeler.nl> X-Mailer: T-Online eMail 2.34 MIME-Version: 1.0 Date: Fri, 30 Jan 2004 17:36:42 +0100 Message-ID: <1AmbdK-1Oy81Z0@fwd03.sul.t-online.com> X-Seen: false X-ID: Gz77z8Z-Ze1UDHwW8vG9TOkqFY1lAra1k3Wjsi4fr0X7X5BN0S9w8m Subject: LF: Zobel Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 8bit X-Spam-Checker-Version: SpamAssassin 2.60 (1.212-2003-09-23-exp) on post.thorcom.com X-Spam-Level: ** X-Spam-Status: No, hits=2.4 required=5.0 tests=FROM_ENDS_IN_NUMS,FROM_STARTS_WITH_NUMS autolearn=no version=2.60 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: rs_out@blacksheep.org X-SA-Exim-Scanned: No; SAEximRunCond expanded to false X-PN-SPAMFiltered: yes X-Spam-Rating: 1 Hi Dave/G3YXM and group, the Zobel Network 22 Ohm / 4,7nF in my G3YXM PA gets very hot if driving the PA in 1kW mode; much hotter than the toroid T2 (output transformer)gets. I changed the five Watt resistor with a 20 Watt, it gets hot too; with the cooling fan off the resistor desolders itself. I think that`s a good sign of the correct dimension: 22 Ohm / 4,7nF means the open reactive load (T2 and surroundings) oscillates at calculated 1,539MHz; measured 1,776MHz. But what a heavy loss! My question: Is there no other possibility eliminating the instability of that output system ? Regards Uwe / dj8wx