Return-Path: X-Spam-DCC: paranoid 1233; Body=3 Fuz1=3 Fuz2=3 X-Spam-Checker-Version: SpamAssassin 3.1.3 (2006-06-01) on lipkowski.org X-Spam-Level: X-Spam-Status: No, score=-0.5 required=5.0 tests=BAYES_00,DNS_FROM_AHBL_RHSBL, FORGED_RCVD_HELO,RATWARE_GECKO_BUILD,SPF_PASS autolearn=no version=3.1.3 Received: from post.thorcom.com (post.thorcom.com [195.171.43.25]) by paranoid.lipkowski.org (8.13.7/8.13.7) with ESMTP id u2AMXEm7006275 for ; Thu, 10 Mar 2016 23:33:14 +0100 Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1ae95S-0006gg-Lb for rs_out_1@blacksheep.org; Thu, 10 Mar 2016 22:29:42 +0000 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1ae95S-0006gW-Cv for rsgb_lf_group@blacksheep.org; Thu, 10 Mar 2016 22:29:42 +0000 Received: from parrot.netcom.co.uk ([217.72.171.49]) by relay1.thorcom.net with esmtp (Exim 4.86) (envelope-from ) id 1ae95Q-0001zZ-RJ for rsgb_lf_group@blacksheep.org; Thu, 10 Mar 2016 22:29:41 +0000 Received: from sb.abelian.org (i-194-106-52-83.freedom2surf.net [194.106.52.83]) by parrot.netcom.co.uk (Postfix) with ESMTP id 528BA3273E8 for ; Thu, 10 Mar 2016 22:29:38 +0000 (GMT) Received: from [127.0.0.1] (localhost [127.0.0.1]) by sb.abelian.org (Postfix) with ESMTP id 426A428A049D for ; Thu, 10 Mar 2016 22:29:39 +0000 (UTC) Message-ID: <56E1F553.1080306@abelian.org> Date: Thu, 10 Mar 2016 22:29:39 +0000 From: Paul Nicholson User-Agent: Mozilla/5.0 (X11; Linux i686; rv:17.0) Gecko/20130329 Thunderbird/17.0.5 MIME-Version: 1.0 To: rsgb_lf_group@blacksheep.org References: <56DEAE40.8000809@tiscali.co.uk> <56DEF9AE.7060203@posteo.de> In-Reply-To: <56DEF9AE.7060203@posteo.de> X-Scan-Signature: a6b6ffaf48fdddf1ed5c25dc4bf03ee1 Subject: Re: LF: EbNaut from Todmorden Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit 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-Scanned-By: MIMEDefang 2.56 on 10.1.3.11 Status: O X-Status: X-Keywords: X-UID: 7294 I rebuilt the PA with bifilar wound choke feeding DC to the push-pull drains and the primary winding on the toroid has no center tap. With no load and with 50 ohms directly on the secondary the drain waveforms are not bad at all - pretty square with some ringing which is not a problem, the FETs are 600V so I won't bother to snub the spikes. Output filter is a T circuit to present a hi-Z load to the PA at the harmonics. Drain waveforms remain OK with the dummy load attached via the T filter. MOSFETs, output transformer and DC supply choke don't get even slightly warm with 120W input, so that's a success thanks to everyone's advice. The coils of the T filter wound on ferrite toroids get very hot very quickly. It's the ferrite producing the heat not the wire. I must have the wrong flavour of ferrite so I ordered some different ones (nice blue EPCOS ones) but they wont arrive till Monday. Meanwhile I'll wind some air cored coils for the filter. A bit of work to do tomorrow on the antenna match and I need to bury some metal for a better RF ground. Then will try some carrier on air. Gary wrote: > Do you realise that [137.5 kHz +- 50 Hz] is already the > established center frequency for Opera & WSPR ?? Convenient for EbNaut also, because the files recorded for use by OPDS can also be used for EbNaut via a conversion program written by Markus, hence Stefan's suggestion. To start with though, I'll probably put some carrier in the QRSS band because that's where the narrow band grabbers seem to be. -- Paul Nicholson --