Return-Path: Received: (qmail 22749 invoked from network); 7 Nov 2003 12:43:24 -0000 Received: from unknown (HELO netmail00.services.quay.plus.net) (212.159.14.218) by mailstore with SMTP; 7 Nov 2003 12:43:24 -0000 Received: (qmail 18157 invoked from network); 7 Nov 2003 12:43:24 -0000 X-Filtered-by: Plusnet (hmail v1.01) X-Spam-detection-level: 11 Received: from post.thorcom.com (193.82.116.20) by netmail00.services.quay.plus.net with SMTP; 7 Nov 2003 12:43:12 -0000 X-Fake-Domain: majordom Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1AI5v4-0006XT-RP for rsgb_lf_group-outgoing@blacksheep.org; Fri, 07 Nov 2003 12:40:54 +0000 Received: from [147.197.200.9] (helo=hestia.herts.ac.uk) by post.thorcom.com with esmtp (Exim 4.14) id 1AI5v1-0006XK-5e for rsgb_lf_group@blacksheep.org; Fri, 07 Nov 2003 12:40:51 +0000 X-Fake-Domain: gemini Received: from gemini ([147.197.200.44] helo=gemini.herts.ac.uk) by hestia.herts.ac.uk with esmtp (Exim 3.22 #1) id 1AI5k4-0005Nk-00 for rsgb_lf_group@blacksheep.org; Fri, 07 Nov 2003 12:29:32 +0000 X-No-DNS-For: 147.197.232.252 Received: from [147.197.232.252] (helo=rsch15) by gemini.herts.ac.uk with esmtp (Exim 3.33 #1) id 1AI5iY-0002Mb-00 for rsgb_lf_group@blacksheep.org; Fri, 07 Nov 2003 12:27:58 +0000 From: "James Moritz" To: rsgb_lf_group@blacksheep.org Date: Fri, 7 Nov 2003 12:27:58 -0000 Organization: University of Hertfordshire X-Bad-Message-ID: no DNS (rsch15) Message-ID: <000001c3a52a$93ce5bd0$fce8c593@rsch15> MIME-Version: 1.0 X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook, Build 10.0.2627 Importance: Normal In-reply-to: X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1106 X-UH-MailScanner: No Virus detected Subject: LF: RE: On Air Testing Content-Type: text/plain; charset=us-ascii; 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-Status: No, hits=0.0 required=5.0 tests=none 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: rsgb_lf_group-outgoing@blacksheep.org X-SA-Exim-Scanned: No; SAEximRunCond expanded to false X-Spam-Rating: 2 Whilst on the subject of dummy loads, are Metal Oxide resistors suitable for dummy loads ? because much higher ratings (5 watts) are available for same physical size as the 2 watt carbon film resistors in my home brew dummy load. 73 Gary - G4WGT Dear Gary, LF Group, The metal oxide types would be fine, as are metal film, etc. In fact, even some types of wirewound resistors are reasonably non-reactive at 136kHz. Several people have resorted to electric heating elements like toasters and fan heaters to make satisfactory LF dummy loads. But obviously, it is a safer bet to stick to known low inductance types like carbon, metal oxide and metal film unless you have the equipment to evaluate the actual RF impedance. The Vishay RCH50 50W film resistors sold by RS components are pretty good value at about 2-3 pounds each, and work OK up to HF - but obviously you need a hefty heatsink as well as the resistors. Cheers, Jim Moritz 73 de M0BMU