Return-Path: Received: (qmail 24563 invoked from network); 13 May 2001 18:58:32 -0000 Received: from unknown (HELO murphys-inbound.servers.plus.net) (212.159.14.225) by excalibur.plus.net with SMTP; 13 May 2001 18:58:32 -0000 Received: (qmail 28502 invoked from network); 13 May 2001 18:58:00 -0000 Received: from unknown (HELO post.thorcom.com) (212.172.148.70) by murphys with SMTP; 13 May 2001 18:58:00 -0000 Received: from majordom by post.thorcom.com with local (Exim 3.16 #2) id 14z0yl-000503-00 for rsgb_lf_group-outgoing@blacksheep.org; Sun, 13 May 2001 19:52:31 +0100 Received: from lepidachrosite.lion-access.net ([212.19.217.3]) by post.thorcom.com with esmtp (Exim 3.16 #2) id 14z0yj-0004zy-00 for rsgb_lf_group@blacksheep.org; Sun, 13 May 2001 19:52:30 +0100 Received: from w8k3f0 (1Cust241.tnt10.rtm1.nl.uu.net [213.116.114.241]) by lepidachrosite.lion-access.net (I-Lab) with SMTP id 8CF36CB2E0 for ; Sun, 13 May 2001 18:51:06 +0000 (GMT) Message-ID: <000801c0dbde$34fb9720$f17274d5@w8k3f0> From: "Dick Rollema" To: rsgb_lf_group@blacksheep.org References: <000601c0dbb8$bc424920$1a8c01d4@g4jnt> Subject: LF: Re: Re: Radiation from loading coil causing difference in current at top and bottom? Date: Sun, 13 May 2001 20:54:11 +0200 MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1; format=flowed Content-Transfer-Encoding: 8bit X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 5.00.2314.1300 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1106 Precedence: bulk Reply-To: rsgb_lf_group@blacksheep.org X-Listname: rsgb_lf_group Sender: To All from PA0SE Andy, G4JNT wrote: > But these harmonic currents will upset your readings somewhat - where on a > scope trace is the RMS value of > a) the total waveform and > b) the fundamental ? > > The harmonic currents will obviously be out of phase with the harmonic > voltage, and cannot exit the top of the coil so if they are indeed entering > the coil base they must be completing their loop in the fields from the coil > itself - the quadrature, non dissipative, H or E fields. Very little > radiation field will be generated from such a small radiating element, even > at harmonic frequencies. The current into the coil, displayed as the voltage over the resistor in series with the coil, looked like a pure sinewave. So the harmonics were only present in the transmitter output VOLTAGE, not in the current into the coil. 73, Dick, PA0SE > >The output voltage of the TX was somewhat distorted due to harmonics, > >showing up as some ripple at the positive and negative peaks of the > >trace but the zero crossings were at exactly the same points as the > voltage > >over the resistor. > >Thus as far as can be judged from oscilloscope traces voltage and current > >at the bottom end of the coil were in phase.