Return-Path: <majordom@post.thorcom.com> Received: (qmail 12536 invoked from network); 6 May 2001 21:04:32 -0000 Received: from unknown (HELO murphys-inbound.servers.plus.net) (212.159.14.225) by excalibur.plus.net with SMTP; 6 May 2001 21:04:32 -0000 Received: (qmail 1714 invoked from network); 6 May 2001 21:04:02 -0000 Received: from unknown (HELO post.thorcom.com) (212.172.148.70) by murphys with SMTP; 6 May 2001 21:04:02 -0000 X-Priority: 3 X-MSMail-Priority: Normal Received: from majordom by post.thorcom.com with local (Exim 3.16 #2) id 14wVci-0005K3-00 for rsgb_lf_group-outgoing@blacksheep.org; Sun, 06 May 2001 21:59:24 +0100 Received: from finch-post-10.mail.demon.net ([194.217.242.38]) by post.thorcom.com with esmtp (Exim 3.16 #2) id 14wVch-0005Jy-00 for rsgb_lf_group@blacksheep.org; Sun, 06 May 2001 21:59:23 +0100 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1106 Received: from alg.demon.co.uk ([194.222.171.80]) by finch-post-10.mail.demon.net with esmtp (Exim 2.12 #1) id 14wVcB-000CNm-0A for rsgb_lf_group@blacksheep.org; Sun, 6 May 2001 20:58:51 +0000 Message-ID: <3AF5BC00.EEF6A5E@alg.demon.co.uk> Date: Sun, 06 May 2001 22:02:56 +0100 From: "Steve Rawlings" <steve@alg.demon.co.uk> X-Mailer: Mozilla 4.6 [en-gb]C-CCK-MCD NetscapeOnline.co.uk (Win98; I) X-Accept-Language: en-GB,en MIME-Version: 1.0 To: "LF Group" <rsgb_lf_group@blacksheep.org> Subject: LF: Measurement of antenna current Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 8bit Precedence: bulk Reply-To: rsgb_lf_group@blacksheep.org X-Listname: rsgb_lf_group Sender: <majordom@post.thorcom.com> Hi All, Today, I made some more antenna current measurements on my 12 m vertical (and my shiny new loading coil), using a thermocouple meter. At resonance, the current into the base of the loading coil, was 2.2 A. But when measuring the current into the antenna at the hot end of the coil, the meter only indicated 1.8 A. I had expected the reading to be the same at both ends of the coil. The loading coil has many more turns than is required to resonate the 12 m vertical, so the connection to the antenna uses a tap which is several turns down from the top of the coil. I've been thinking that the excess turns at the top of the coil may be causing the difference in current readings. (This may sound silly, but in my mind's eye, I can sort of picture some of the current in the coil going into the capacitance of the antenna; and some current going into the capacitance of the unused turns.) Before I try removing the excess turns, I'd like to know whether the current should indeed be the same at both ends of the loading coil. Can anyone help? Regards to all, Steve GW4ALG