Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on lipkowski.org X-Spam-Level: X-Spam-Status: No, score=-2.3 required=5.0 tests=FREEMAIL_FORGED_FROMDOMAIN, FREEMAIL_FROM,HEADER_FROM_DIFFERENT_DOMAINS,RCVD_IN_DNSWL_MED,SPF_PASS, T_DKIM_INVALID autolearn=ham autolearn_force=no version=3.4.0 X-Spam-DCC: dcc1: mailn 1182; Body=2 Fuz1=2 Fuz2=2 Received: from post.thorcom.com (post.thorcom.com [195.171.43.25]) by lipkowski.org (8.14.4/8.14.4/Debian-8+deb8u1) with ESMTP id v4OEvGhF004761 for ; Wed, 24 May 2017 16:57:18 +0200 Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1dDXZK-0004Y5-EE for rs_out_1@blacksheep.org; Wed, 24 May 2017 15:47:22 +0100 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1dDXZJ-0004Xw-Hy for rsgb_lf_group@blacksheep.org; Wed, 24 May 2017 15:47:21 +0100 Received: from mail-wr0-x232.google.com ([2a00:1450:400c:c0c::232]) by relay1.thorcom.net with esmtps (TLSv1.2:ECDHE-RSA-AES256-GCM-SHA384:256) (Exim 4.89) (envelope-from ) id 1dDXZF-00020x-Qs for rsgb_lf_group@blacksheep.org; Wed, 24 May 2017 15:47:20 +0100 Received: by mail-wr0-x232.google.com with SMTP id j27so2674319wre.1 for ; Wed, 24 May 2017 07:47:17 -0700 (PDT) X-DKIM-Result: Domain=gmail.com Result=Good and Known Domain DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=from:date:message-id:to:subject:mime-version :content-transfer-encoding; bh=xK432Fr2stZxhBwWnYOBUTga/Ad3dT2bVKrfMUVBFaI=; b=KA36w0clGFdmefA7cqy2RYv+Yn6BW7W4YxzsLMM9u68mTPZ1sUMBJ1l3KCvBJrb0nG bzfa4mi24CUandof/QdBeLuDdhWnNwv4tNKvieIHfldOLjhTZJUypNSMU1u6L4QQjZ9C p3S6yuFLYV96uEiLTmm8phfbjdk/CbT7DaPCZyLL+MLTkfje97B6SnamHdnQ9LIqO0NZ GU/V9K0x4neChr96aDFMekijU05a3V4PXRg4bxEjCw6eALss0Q5HQwDu0rWCrfUhfqK8 Hkfbl2+qMcKQpg5MDEJuxMXrg++8dPv1WrSd0HCbdwLDrhLhpTxvTJd/MbcyEuRolRcp mJJg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:date:message-id:to:subject:mime-version :content-transfer-encoding; bh=xK432Fr2stZxhBwWnYOBUTga/Ad3dT2bVKrfMUVBFaI=; b=eZh5AWPt/vKJ9WicWxTRFreBaNV5w3tL+EyJMsZUCHqstSSLeWvAuDfa3zjBjpOXse h8xY9LJVFjp3ByelR+l3Tg2oyrhSyLtvjbLCdX5/eO68FIdWJS/pPjTLc51ftgtxtAMQ UG1IYmMGr9JAVRTq3zE1fDdJKPyUi8CkP/rfJtw24ZTCzf8DakNp27curo8TzfJDdfL4 T7wbFpweFBTZeCxbGrt4QakqD2naxVLXpIZdNKQNrZx5Nw8LvuRcI7osnKQl4aViXVXR JPDxF8uUY+BFM7OwnET1T8lBcVUVa3uXxV5SN8l8nIv4tgIIGiwgqHkzh/dHHHZnFh5N p4Ag== X-Gm-Message-State: AODbwcCURfyIIMoSyKw6FQOTHVQSfloZzhViIz6U3Y7cyILGSoXXTa28 sn6zyXGMQds5ZJWL X-Received: by 10.223.132.132 with SMTP id 4mr20090375wrg.31.1495637235461; Wed, 24 May 2017 07:47:15 -0700 (PDT) Received: from OfficeWin7.lan (82-70-254-222.dsl.in-addr.zen.co.uk. [82.70.254.222]) by smtp.gmail.com with ESMTPSA id o18sm6311670wrb.47.2017.05.24.07.47.14 for (version=TLS1 cipher=AES128-SHA bits=128/128); Wed, 24 May 2017 07:47:14 -0700 (PDT) From: Chris Wilson X-Google-Original-From: Chris Wilson Date: Wed, 24 May 2017 15:47:13 +0100 X-Priority: 3 (Normal) Message-ID: <1456380282.20170524154713@gmail.com> To: rsgb_lf_group@blacksheep.org MIME-Version: 1.0 X-Scan-Signature: 7001055fa59a9c23b9831ea6d317a074 Subject: LF: Iron dust toroids and heating Content-Type: text/plain; charset=us-ascii 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 2.75 Status: RO X-Status: X-Keywords: X-UID: 11750 Hello LF'ers, 24 May 2017 If I run the combiner on my 2 amps the LPF centre toroid heats up. I made a silly mistake with setting my U3S driver the other night and instead of TX'ing every 30 minutes it went on an every two minute rampage before it soon self halted. The centre toroid winding has lost most of its enamel coating and the Kaptan tape is crispy. It no longer functions as an LPF, and I suspect the T225A-2 toroid is compromised in its crystalline structure, through the very high temperatures, now. 115uH seems to be the calculated figure, if not actually measured (73 turns 14 AWG enamelled wire) of the centre inductor. An air core coil of similar inductance isn't THAT big, (at least not the size of a "small car" as someone on a US forum estimated :)) Is an air cored LPF viable, or do i need to look at different core sizes or materials? Thanks. LPF is at: http://www.w1vd.com/LPF.html Thanks. -- Best regards, Chris mailto:dead_fets@gmail.com