Return-Path: X-Spam-DCC: paranoid 1102; Body=2 Fuz1=2 Fuz2=2 X-Spam-Checker-Version: SpamAssassin 3.1.3 (2006-06-01) on lipkowski.org X-Spam-Level: X-Spam-Status: No, score=-0.7 required=5.0 tests=BAYES_00,DNS_FROM_AHBL_RHSBL, 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 u4EC68xA027691 for ; Sat, 14 May 2016 14:06:08 +0200 Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1b1YG4-0004AH-1D for rs_out_1@blacksheep.org; Sat, 14 May 2016 13:01:24 +0100 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1b1YG3-0004A8-3A for rsgb_lf_group@blacksheep.org; Sat, 14 May 2016 13:01:23 +0100 Received: from mout01.posteo.de ([185.67.36.65]) by relay1.thorcom.net with esmtps (TLSv1.2:ECDHE-RSA-AES256-GCM-SHA384:256) (Exim 4.87) (envelope-from ) id 1b1YG1-0004Hb-6f for rsgb_lf_group@blacksheep.org; Sat, 14 May 2016 13:01:21 +0100 Received: from dovecot03.posteo.de (dovecot03.posteo.de [172.16.0.13]) by mout01.posteo.de (Postfix) with ESMTPS id 4C3BE202C5 for ; Sat, 14 May 2016 14:01:17 +0200 (CEST) Received: from mail.posteo.de (localhost [127.0.0.1]) by dovecot03.posteo.de (Postfix) with ESMTPSA id 3r6QL53gsFz5vMw for ; Sat, 14 May 2016 14:01:17 +0200 (CEST) Message-ID: <5737138D.4050807@posteo.de> Date: Sat, 14 May 2016 14:01:17 +0200 From: DK7FC 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" X-Scan-Signature: 6ffbd2c9950b634d6cc91f9565b01a8b Subject: LF: A transductor instead of a traditional variometer on VLF/LF/MF? Content-Type: text/plain; charset=ISO-8859-15; format=flowed Content-Transfer-Encoding: 8bit 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: 8057 Hi all, During thinking about a solution for a automatic variometer for my VLF coil i got the idea of using a transductor instead. Will this work? See: https://de.wikipedia.org/wiki/Transduktor_%28Elektrotechnik%29 https://en.wikipedia.org/wiki/Magnetic_amplifier On LF/MF and VLF many of us are using typical variometers for manual or automatic resonance correction of the transmit system. Due to the multi-layer VLF TX coil with a forced air flow in the center it is not easy (or not possible) to put an additional rotatable coil in the center to adjust the resonance frequency within a small range. So i need another solution. One solution could be to accept the non-resonance and run a higher voltage on the output transformer to keep the antenna current constant. But this will cause losses on the linear working PA and works only in a very limited range, due to the Q of the system. So it would be better to have a chance to steer the resonance anyway! But how? Now, what about a transductor? A ferrite core inside the main field of the coil. It must have a winding and a variable DC current from an external power supply. The DC current can saturate the core and change its effective µr for the external AC magnetic field. If this works, then it is a non-mechanical solution! No motor, no axis, no end switches, no mechanical self oscillation, no broken RF litz wire on the rotating elements, fast changing of the resonance frequency. Has someone tried that on LF before? 73, Stefan PS: I will start to try that on VLF, IMMEDIATELY! :-)