Return-Path: Received: (qmail 16187 invoked from network); 27 Feb 2004 18:31:09 -0000 Received: from unknown (HELO ptb-mxscan03.plus.net) (212.159.14.237) by ptb-mailstore03.plus.net with SMTP; 27 Feb 2004 18:31:09 -0000 Received: (qmail 53674 invoked from network); 27 Feb 2004 18:31:08 -0000 X-Filtered-by: Plusnet (hmail v1.01) X-Spam-detection-level: 11 Received: from ptb-mxcore03.plus.net (212.159.14.217) by ptb-mxscan03.plus.net with SMTP; 27 Feb 2004 18:31:07 -0000 Received: from post.thorcom.com ([193.82.116.20]) by ptb-mxcore03.plus.net with esmtp (Exim) id 1AwmlO-000Dba-Sg for dave@picks.force9.co.uk; Fri, 27 Feb 2004 18:31:07 +0000 X-Fake-Domain: majordom Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1AwmkK-0004WO-61 for rs_out@blacksheep.org; Fri, 27 Feb 2004 18:30:00 +0000 Received: from [213.40.2.14] (helo=gourd.sout.netline.net.uk) by post.thorcom.com with esmtp (Exim 4.14) id 1AwmkJ-0004W9-9v for rsgb_lf_group@blacksheep.org; Fri, 27 Feb 2004 18:29:59 +0000 Received: from [213.40.203.124] (helo=taylormade) by gourd.sout.netline.net.uk with smtp (Exim 4.24) id 1Awmjn-0005MK-V1 for rsgb_lf_group@blacksheep.org; Fri, 27 Feb 2004 18:29:28 +0000 From: "G4WGT - Gary" To: rsgb_lf_group@blacksheep.org Date: Fri, 27 Feb 2004 18:29:39 -0000 Message-ID: MIME-Version: 1.0 X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook IMO, Build 9.0.2416 (9.0.2910.0) Importance: Normal In-reply-to: <000001c3fad1$785a5280$fce8c593@RD40004> X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1106 Subject: LF: RE: RE: RF Current meter Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 8bit X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on post.thorcom.com X-Spam-Status: No, hits=0.0 required=5.0 tests=none autolearn=no version=2.63 X-SA-Exim-Scanned: Yes Sender: Precedence: bulk Reply-To: rsgb_lf_group@blacksheep.org X-Listname: rsgb_lf_group X-SA-Exim-Rcpt-To: rs_out@blacksheep.org X-SA-Exim-Scanned: No; SAEximRunCond expanded to false X-PN-SPAMFiltered: yes X-Spam-Rating: 1 Hello Jim & LF Group, Thank you for your recent e-mail, I have seen your design in the recent past but did not give it much thought, but I see from your comments & reading the associated article http://www.picks.plus.com/software/LFtunemeter.pdf that it will be a very worthwile piece of gear to construct. The only query at the moment is regarding the phase meter (1mA-0-1mA), if I were to use a 100uA-0-100uA meter with a shunt would this cause any problems with your design or maybe increasing the value of R2 would be acceptable, (I have this meter already in my junk box), the 1mA meter for V & A metering is not a problem. Just had another thought, I presume that the device is to be inserted in the coax feed prior to the antenna matching arrangement at the antenna end. 73 Gary - G4WGT -----Original Message----- From: owner-rsgb_lf_group@blacksheep.org [mailto:owner-rsgb_lf_group@blacksheep.org]On Behalf Of James Moritz Sent: 24 February 2004 12:27 To: rsgb_lf_group@blacksheep.org Subject: LF: RE: RF Current meter Dear Gary, LF Group, The RF ammeter circuit in the LF handbook and on K0LR's web page uses a current transformer to develop a voltage of a few volts across a load resistor when the appropriate RF current is flowing in the primary. This voltage is then measured by a simple diode voltmeter to indicate the current. Sounds pretty simple then, but some pitfalls are possible with an RF ammeter of this type...etc.