Return-Path: Received: (qmail 41992 invoked from network); 27 Feb 2004 23:20:50 -0000 Received: from unknown (HELO ptb-mxscan03.plus.net) (212.159.14.237) by ptb-mailstore03.plus.net with SMTP; 27 Feb 2004 23:20:50 -0000 Received: (qmail 88347 invoked from network); 27 Feb 2004 23:20:49 -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 23:20:45 -0000 Received: from post.thorcom.com ([193.82.116.20]) by ptb-mxcore03.plus.net with esmtp (Exim) id 1AwrHg-000MXJ-Qv for dave@picks.force9.co.uk; Fri, 27 Feb 2004 23:20:44 +0000 X-Fake-Domain: majordom Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1AwrH7-0004Bb-OV for rs_out@blacksheep.org; Fri, 27 Feb 2004 23:20:09 +0000 Received: from [194.73.73.92] (helo=carbon.btinternet.com) by post.thorcom.com with esmtp (Exim 4.14) id 1AwrH7-0004BS-6a for rsgb_lf_group@blacksheep.org; Fri, 27 Feb 2004 23:20:09 +0000 Received: from [213.122.28.110] (helo=rogersservices) by carbon.btinternet.com with esmtp (Exim 3.22 #25) id 1AwrH6-0003v4-00 for rsgb_lf_group@blacksheep.org; Fri, 27 Feb 2004 23:20:08 +0000 X-Bad-Message-ID: no DNS (rogersservices) Message-ID: <001301c3fd87$a99173c0$6e1c7ad5@rogersservices> From: "James Moritz" To: rsgb_lf_group@blacksheep.org References: Date: Fri, 27 Feb 2004 23:15:59 -0000 MIME-Version: 1.0 X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 5.00.2615.200 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1106 Subject: LF: Re: RE: RE: RF Current meter Content-Type: text/plain; charset=iso-8859-1; 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: 2 Dear Gary, LF Group, Using a 100u-0-100u meter should not be a problem. The phase detector circuit has a full scale output of around +/-250mV, with a fairly low source impedance - just select a series resistor R2 for your meter that will give a full scale reading with 250mV DC applied. Shunting the meter movement should work fine too, but it needs 1 more resistor. The exact calibration will vary somewhat with the forward voltage of the particular diodes used, and the applied power level. The calibration is not critical, however, since you are really only looking for a zero reading anyway. The meter is normally connected between the transmitter output, and the feeder to the loading coil and matching transformer. A reasonably low harmonic content at the TX output is needed for the phase meter to work properly - but with the usual push-pull TX output and 2 section low-pass filter, this should not be a problem. Cheers, Jim Moritz 73 de M0BMU ----- Original Message ----- From: G4WGT - Gary To: Sent: Friday, February 27, 2004 6:29 PM Subject: LF: RE: RE: RF Current meter > Hello Jim & LF Group, > 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 >