Return-Path: Received: from rly-df03.mx.aol.com (rly-df03.mail.aol.com [172.19.156.16]) by air-df04.mail.aol.com (v123.4) with ESMTP id MAILINDF042-53d49ff66bc1ad; Mon, 04 May 2009 18:05:52 -0400 Received: from post.thorcom.com (post.thorcom.com [193.82.116.20]) by rly-df03.mx.aol.com (v123.4) with ESMTP id MAILRELAYINDF036-53d49ff66bc1ad; Mon, 04 May 2009 18:05:49 -0400 Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1M16Ha-0007r8-Kz for rs_out_1@blacksheep.org; Mon, 04 May 2009 23:05:06 +0100 Received: from [193.82.116.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1M16Ha-0007qz-9I for rsgb_lf_group@blacksheep.org; Mon, 04 May 2009 23:05:06 +0100 Received: from mhost03c.leeds.ac.uk ([129.11.76.167]) by relay1.thorcom.net with esmtp (Exim 4.63) (envelope-from ) id 1M16HX-0004Jy-4K for rsgb_lf_group@blacksheep.org; Mon, 04 May 2009 23:05:05 +0100 Received: from APOLLO1.ds.leeds.ac.uk (apollo1.leeds.ac.uk [129.11.5.4]) by mhost03c.leeds.ac.uk (8.14.3/8.14.3) with ESMTP id n44LvRwS000427 (version=TLSv1/SSLv3 cipher=AES128-SHA bits=128 verify=NOT) for ; Mon, 4 May 2009 22:57:27 +0100 (BST) Received: from HERMES8.ds.leeds.ac.uk ([fe80::39ce:23e:d0b5:7e24]) by APOLLO1.ds.leeds.ac.uk ([129.11.5.4]) with mapi; Mon, 4 May 2009 22:57:27 +0100 From: Chris Trayner To: "rsgb_lf_group@blacksheep.org" Date: Mon, 4 May 2009 22:57:26 +0100 Thread-Topic: Field Strength Meter - advice needed Thread-Index: AcnME/viiC8EuiHYQ0WmpClnaw6UaQA7ozT6 Message-ID: <38F4A9873A5B474DB6FB337B1B69ABA11229299ACD@HERMES8.ds.leeds.ac.uk> References: <260286.17766.qm@web28508.mail.ukl.yahoo.com> In-Reply-To: <260286.17766.qm@web28508.mail.ukl.yahoo.com> Accept-Language: en-US, en-GB Content-Language: en-GB X-MS-Has-Attach: X-MS-TNEF-Correlator: acceptlanguage: en-US, en-GB MIME-Version: 1.0 X-Karma: unknown: X-Spam-Score: 0.0 (/) X-Spam-Report: autolearn=disabled,none Subject: LF: RE: Field Strength Meter - advice needed Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: quoted-printable X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on post.thorcom.com X-Spam-Level: X-Spam-Status: No, hits=0.0 required=5.0 tests=TO_ADDRESS_EQ_REAL autolearn=no version=2.63 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-AOL-IP: 193.82.116.20 X-Mailer: Unknown (No Version) Hi Chris, You've probably thought of these, but just in case: > I have made a decent Helmholtz coil which gives a stable magnetic field ye= t the field strength meter's output voltage is very dependent on temperature and c= an vary up to 30 %. Is the Helmholtz coil getting a constant voltage from the sig gen, or whatev= er powers it? That's not temp-sensitive, is it? If you're attenuating the sig gen signal a lot to feed a weak signal to the=20= Helmholtz coil, is the attenuator the problem? Is there any other, unintended signal coupling (e.g. capacitive) from your s= ource of test signal to the field strength meter? Is there any other source of RF you can test it on, e.g. re-tune it to some=20= broadcast signal? 73, Chris G4OKW