Received: from post.thorcom.com (post.thorcom.com [195.171.43.25]) by mtain-db02.r1000.mx.aol.com (Internet Inbound) with ESMTP id 7750F3800011F; Thu, 8 Sep 2011 10:29:31 -0400 (EDT) Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1R1fan-0002hN-2n for rs_out_1@blacksheep.org; Thu, 08 Sep 2011 15:28:37 +0100 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1R1fam-0002hE-NI for rsgb_lf_group@blacksheep.org; Thu, 08 Sep 2011 15:28:36 +0100 Received: from relay2.uni-heidelberg.de ([129.206.210.211]) by relay1.thorcom.net with esmtp (Exim 4.63) (envelope-from ) id 1R1fak-0002kM-UG for rsgb_lf_group@blacksheep.org; Thu, 08 Sep 2011 15:28:36 +0100 Received: from freitag.iup.uni-heidelberg.de (freitag.iup.uni-heidelberg.de [129.206.29.204]) by relay2.uni-heidelberg.de (8.13.8/8.13.8) with ESMTP id p88ESXas030480 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=NO) for ; Thu, 8 Sep 2011 16:28:34 +0200 Received: from [129.206.22.206] (pc206.iup.uni-heidelberg.de [129.206.22.206]) by freitag.iup.uni-heidelberg.de (8.12.11.20060308/8.11.2) with ESMTP id p88ESXbi032515 for ; Thu, 8 Sep 2011 16:28:33 +0200 Message-ID: <4E68D105.5040708@iup.uni-heidelberg.de> Date: Thu, 08 Sep 2011 16:28:21 +0200 From: =?ISO-8859-1?Q?Stefan_Sch=E4fer?= User-Agent: Mozilla/5.0 (Windows; U; Windows NT 6.1; de; rv:1.9.1.8) Gecko/20100227 Thunderbird/3.0.3 MIME-Version: 1.0 To: rsgb_lf_group@blacksheep.org References: <002001cc6e1b$e0b6caf0$ae01a8c0@youry0mkaz8jaq> <135A26CC-BAEF-411C-9B4A-C7A46810C6A2@gmail.com> <60DADF9AC0654400A3D262FD00F8996C@IBM7FFA209F07C> <4918D1ECBF4A43FDBF13FB205CAA9339@IBM7FFA209F07C> In-Reply-To: X-Spam-Score: 1.4 (+) X-Spam-Report: autolearn=disabled,RATWARE_GECKO_BUILD=1.426 Subject: Re: LF: Re: 137.7682kHz QRSS30 beaconing - reports appreciated Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on post.thorcom.com X-Spam-Level: X-Spam-Status: No, hits=0.0 required=5.0 tests=none autolearn=no version=2.63 X-SA-Exim-Scanned: Yes Sender: owner-rsgb_lf_group@blacksheep.org Precedence: bulk Reply-To: rsgb_lf_group@blacksheep.org X-Listname: rsgb_lf_group X-SA-Exim-Rcpt-To: rs_out_1@blacksheep.org X-SA-Exim-Scanned: No; SAEximRunCond expanded to false x-aol-global-disposition: G X-AOL-SCOLL-SCORE: 0:2:480866976:93952408 X-AOL-SCOLL-URL_COUNT: 0 x-aol-sid: 3039ac1d40564e68d14a1865 X-AOL-IP: 195.171.43.25 X-AOL-SPF: domain : blacksheep.org SPF : none Roger, If that small heat sink actually remains cold, efficiency must be quite good! Even switching the FET without a drain current causes losses... Since the IRF540 is a 100V device, you have plenty of space for QRO :-) Nice circuit. It shows how easy one can build a LF PA! Not much difference for a 500W type, just the FET has to be changed to a IRFP260N or so... 73, Stefan/DK7FC Am 08.09.2011 15:33, schrieb Roger Lapthorn: > Photos of (a) the 137kHz QRSS30 beacon and (b) the 137kHz transverter > are on my blog page at > http://g3xbm-qrp.blogspot.com/2011/09/lf-kit-improvements.html . > Subject to test results, both may be tidied up and boxed later. > Otherwise it is back to the bench. > > The PAs run almost cold, whereas my 50 ohm dummy load is very hot, > suggesting very good efficiency from the IRF540 device in each case. > > 73s > Roger G3XBM > >