Return-Path: Received: from post.thorcom.com (post.thorcom.com [195.171.43.25]) by klubnl.pl (8.14.4/8.14.4/Debian-8+deb8u2) with ESMTP id x0CD3Hoq008555 for ; Sat, 12 Jan 2019 14:03:23 +0100 Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1giIsR-0003ps-FQ for rs_out_1@blacksheep.org; Sat, 12 Jan 2019 12:59:03 +0000 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1giIsR-0003pj-2V for rsgb_lf_group@blacksheep.org; Sat, 12 Jan 2019 12:59:03 +0000 Received: from mail-qk1-x736.google.com ([2607:f8b0:4864:20::736]) by relay1.thorcom.net with esmtps (TLSv1.2:ECDHE-RSA-AES256-GCM-SHA384:256) (Exim 4.89) (envelope-from ) id 1giIsP-0000o5-G6 for rsgb_lf_group@blacksheep.org; Sat, 12 Jan 2019 12:59:01 +0000 Received: by mail-qk1-x736.google.com with SMTP id q8so8149848qke.1 for ; Sat, 12 Jan 2019 04:59:01 -0800 (PST) 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=mime-version:from:date:message-id:subject:to; bh=CwMjqk57aNejvRlAqGEDpUitzBfWHmJm9ffUzlG68o8=; b=Iym5QxTbXDoKlYt3mz3yz+lELCpiGc9kvTcZh2mQ1ob+hY8567oQ34WP9+cKdTuHVP DxuerPPkrq1Fc0HZtq7DkiQRREO6rKDx4Zge/MOfokRdM/pF8BXKD/maxiX5N+lxQkeO JlUM1a6lzt6QgbjCW+/Wtn0Mg8GS5V1uUK/ybaXApk7VB6UN/tSK3LHhkAI9JKnFyks1 MHOWTtdu8ux2m4Dnvc2xLF5Nvd1Uq7gr8Z9cuFer8v9Z6JB5NR7ECwpPaOcOP/5EhCZQ jiAcVasegySlDMGrOBItOjfAvXrna6j1OZ8zsxLeQa5hAM9jgeydi4r6AYRkdfg6CQyQ HqNQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:from:date:message-id:subject:to; bh=CwMjqk57aNejvRlAqGEDpUitzBfWHmJm9ffUzlG68o8=; b=MGj9qN57+gWQmXjYB0NUGdftQP0pFxDWTf8QhhGUYRPGU/Qq3iEWHFiV+db1gf0BTg 1y5eBDWzknof5HPPRsJS1JTDeb4cEDHoQsiq1g+wKM6uK/5NFjSvtLdwQ/N3JDFyzmYE x7MrUDgjvkgBRmsHF7dTNnh/Jos5zQ14Z8NYp9Y7YMW1EK1fs/vnvWM46kZ7IT5IaCo+ bOXkeXUKLACYxt9yxOY8vNlLueLmS8UqF2A89Br5M8eM/TzYev34vzVaAeVksx/bClkn rqY9t+KajcZltxSog9YHF1Az1wAKxGhb/QXmHMAlNtKJb7GSkCsh1Qgm61OwBQkvPyiw KICg== X-Gm-Message-State: AJcUukdDCXf6r4TZkZKADUPoYqGeu3+b/wsukpPItSg5zyePdxsPDxUO 9u54XhQWXI4gD+ZXBqHSDfZUMKnntOqaDirV8pJ+Iw== X-Google-Smtp-Source: ALg8bN4eh47LkndH9/eY4GWKXMt/ySFrDZi0t8/X6JSS+661TOSV2gJAu6UgGH/0xOq0Tb76cP6z3NcmIWMqRVre+pY= X-Received: by 2002:a37:8b41:: with SMTP id n62mr15302103qkd.262.1547264930999; Fri, 11 Jan 2019 19:48:50 -0800 (PST) MIME-Version: 1.0 From: Dimitrios Tsifakis Date: Sat, 12 Jan 2019 14:48:40 +1100 Message-ID: To: rsgb_lf_group@blacksheep.org X-Spam-Score: 1.1 (+) X-Spam-Report: Spam detection software, running on the system "relay1.thorcom.net", has NOT identified this incoming email as spam. The original message has been attached to this so you can view it or label similar future email. If you have any questions, see @@CONTACT_ADDRESS@@ for details. Content preview: Hi LF group, I have managed to acquire a few very large ferrite rods (36 cm x 10 cm x 2 cm). The material is unknown but I managed to form a square 'toroid' with four of them (they are heavy so gravity was enough [...] Content analysis details: (1.1 points, 5.0 required) pts rule name description ---- ---------------------- -------------------------------------------------- -0.0 RCVD_IN_DNSWL_NONE RBL: Sender listed at http://www.dnswl.org/, no trust [2607:f8b0:4864:20:0:0:0:736 listed in] [list.dnswl.org] -0.0 SPF_PASS SPF: sender matches SPF record 1.1 DATE_IN_PAST_06_12 Date: is 6 to 12 hours before Received: date 0.0 FREEMAIL_FROM Sender email is commonly abused enduser mail provider (dtsifakis[at]gmail.com) 0.0 T_DKIM_INVALID DKIM-Signature header exists but is not valid X-Scan-Signature: 59677119386dcf9f1872cb454dc1331d Subject: LF: a lot of ferrite Content-Type: text/plain; charset="UTF-8" X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on post.thorcom.com X-Spam-Level: X-Spam-Status: No, hits=0.6 required=5.0 tests=DATE_IN_PAST_06_12 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 Hi LF group, I have managed to acquire a few very large ferrite rods (36 cm x 10 cm x 2 cm). The material is unknown but I managed to form a square 'toroid' with four of them (they are heavy so gravity was enough to keep everything in place for a measurement) and I measured about 15 uH for 4 turns at 0.1 MHz, which if I have done the calculations correctly implies a relative permeability of about 1000. The R of the impedance of the square loop was low (<0.2 ohm) at 0.1 MHz and it increased fast with frequency (170 ohm at 5 MHz!). The question is, what LF/VLF experiment would you do if you had half a dozen of these rods? 73, Dimitris VK2COW