Return-Path: X-Spam-DCC: paranoid 1170; 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=-2.4 required=5.0 tests=BAYES_00,DNS_FROM_AHBL_RHSBL 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 t9KAKF3p031620 for ; Tue, 20 Oct 2015 12:20:15 +0200 Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1ZoTyF-0003cD-OL for rs_out_1@blacksheep.org; Tue, 20 Oct 2015 11:16:43 +0100 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1ZoTyF-0003c4-Fv for rsgb_lf_group@blacksheep.org; Tue, 20 Oct 2015 11:16:43 +0100 Received: from know-smtprelay-omc-11.server.virginmedia.net ([80.0.253.75]) by relay1.thorcom.net with esmtp (Exim 4.86) (envelope-from ) id 1ZoTx5-0004r0-Rk for rsgb_lf_group@blacksheep.org; Tue, 20 Oct 2015 11:16:42 +0100 Received: from [192.168.1.6] ([86.31.33.210]) by know-smtprelay-11-imp with bizsmtp id XNFF1r00C4Y1DuW01NFFCk; Tue, 20 Oct 2015 11:15:15 +0100 X-Originating-IP: [86.31.33.210] X-Spam: 0 X-Authority: v=2.1 cv=dtgmcAU4 c=1 sm=1 tr=0 a=jn/JOh/JfiX48zzdjRLp/g==:117 a=jn/JOh/JfiX48zzdjRLp/g==:17 a=NLZqzBF-AAAA:8 a=kj9zAlcOel0A:10 a=Cav3IdC4iDYISjPsqkoA:9 a=CjuIK1q_8ugA:10 From: "Mike Dennison" To: rsgb_lf_group@blacksheep.org Date: Tue, 20 Oct 2015 11:15:13 +0100 MIME-Version: 1.0 Message-ID: <56262241.14467.4B37EB@mike.dennison.ntlworld.com> In-reply-to: <174420693.20151020102516@chriswilson.tv> References: <1435044716.20151018182802@chriswilson.tv>, , <174420693.20151020102516@chriswilson.tv> X-mailer: Pegasus Mail for Windows (4.41) Content-description: Mail message body X-Scan-Signature: 87966b345956c8ef3389b993f6a18f4e Subject: Re: Re[2]: LF: Where to measure antenna current? 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 2.56 on 10.1.3.10 Status: O X-Status: X-Keywords: X-UID: 4546 > Thanks John, yes it does help, much appreciated, but what I am still > unsure of is if my Scopematch, that shows voltage and current > waveforms, is also, on the current waveform, displaying antenna > current? Does it not "do the same job" as a current meter? Your scope match measures the current in the feeder. This is not the same as that in the antenna which may be a different impedance - which is why you need a matching circuit (eg transformer). You can measure the current at the (relatively) 'cold' end of the loading coil where it meets the matching unit, so there's no need to deal with the very high volts on the antenna wire itself. You can also measure it in the earth lead, but I would not rely on earth current whilst you still appear to have too much stray RF (see my earlier posting). A current meter is easy to build. You don't even need to calbrate it in the short term as you are unlikely to go anywhere near the legal max ERP.. 73 de Mike, G3XDV