Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on lipkowski.org X-Spam-Level: X-Spam-Status: No, score=0.5 required=5.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, RCVD_IN_SORBS_SPAM,SPF_PASS,T_HK_NAME_DR autolearn=no autolearn_force=no version=3.4.0 X-Spam-DCC: : mailn 1480; 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+deb8u2) with ESMTP id v755oNnl012259 for ; Sat, 5 Aug 2017 07:50:24 +0200 Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1ddrnk-000179-NR for rs_out_1@blacksheep.org; Sat, 05 Aug 2017 06:39:04 +0100 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1ddrnO-000170-MJ for rsgb_lf_group@blacksheep.org; Sat, 05 Aug 2017 06:38:42 +0100 Received: from mailout09.t-online.de ([194.25.134.84]) by relay1.thorcom.net with esmtps (TLSv1.2:ECDHE-RSA-AES256-GCM-SHA384:256) (Exim 4.89) (envelope-from ) id 1ddrnL-0006S8-OM for rsgb_lf_group@blacksheep.org; Sat, 05 Aug 2017 06:38:41 +0100 Received: from fwd33.aul.t-online.de (fwd33.aul.t-online.de [172.20.27.144]) by mailout09.t-online.de (Postfix) with SMTP id 8B063424BEF7 for ; Sat, 5 Aug 2017 07:38:37 +0200 (CEST) Received: from [192.168.1.3] (TFwEUoZarhIZl6jEMw998vtlMlUtxVYyYz99LTt+sJKMlFP8SSiNpjk7r3a2V2Ew7m@[31.212.22.23]) by fwd33.t-online.de with (TLSv1.2:ECDHE-RSA-AES256-GCM-SHA384 encrypted) esmtp id 1ddrnJ-1XmnFg0; Sat, 5 Aug 2017 07:38:37 +0200 To: rsgb_lf_group@blacksheep.org References: <0883B95D3F4D417F975C59A900E1A838@gnat> <3D9A092BFA65418DBEE13188A4C58580@gnat> From: "Dr. Wolf Ostwald" Message-ID: <92ce2c22-a887-bb8f-6bc2-6f03b51899d6@t-online.de> Date: Sat, 5 Aug 2017 07:38:38 +0200 User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:52.0) Gecko/20100101 Thunderbird/52.2.1 MIME-Version: 1.0 In-Reply-To: <3D9A092BFA65418DBEE13188A4C58580@gnat> X-ID: TFwEUoZarhIZl6jEMw998vtlMlUtxVYyYz99LTt+sJKMlFP8SSiNpjk7r3a2V2Ew7m X-TOI-MSGID: 9f806124-faf1-4e83-ac32-4a7949e76e33 X-Scan-Signature: 87966b345956c8ef3389b993f6a18f4e Subject: LF: G4HUP aerial current meter/ hazards Content-Type: text/plain; charset=utf-8; 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 2.75 Status: RO X-Status: X-Keywords: X-UID: 12327 good morning ! a current transformer with ferrites of unknown origin and virtues is a very risky thing. As these cores are widely available on swapmeets its a lure to use them. But they can be tested. I blew a few of them by just putting them on with a single primary turn and with power less than a hundred watts they got hot and broke. The losses can be extremely high. It does not help to measure their magnetic constant. As that has not much to do with frequency dependent losses. a way to find out is to use a 50 ohm load and measure the RF voltage across the terminals. Then u just put the toroid over the "hot" side of the resistor terminals. If the measured RF voltage drops heavily, the core is useless. You dont want it to block, u want to derive some RF for measuring purposes. The above core would go into pieces and additionally as it poses a high inductance to ur feedline, the amplifier stage may go south, depending on the safety factor involved with ur construction . 73 de wolf df2py