Return-Path: Received: from rly-dc03.mx.aol.com (rly-dc03.mail.aol.com [172.19.136.32]) by air-dc03.mail.aol.com (v125.7) with ESMTP id MAILINDC034-b104accf8b9183; Wed, 07 Oct 2009 16:23:39 -0400 Received: from post.thorcom.com (post.thorcom.com [193.82.116.20]) by rly-dc03.mx.aol.com (v125.7) with ESMTP id MAILRELAYINDC034-b104accf8b9183; Wed, 07 Oct 2009 16:23:23 -0400 Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1Mvd1v-0000ck-Gt for rs_out_1@blacksheep.org; Wed, 07 Oct 2009 21:22:35 +0100 Received: from [193.82.116.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1Mvd1v-0000cb-5G for rsgb_lf_group@blacksheep.org; Wed, 07 Oct 2009 21:22:35 +0100 Received: from smarthost1.mail.uk.easynet.net ([212.135.6.11]) by relay1.thorcom.net with esmtp (Exim 4.63) (envelope-from ) id 1Mvd0V-0006ee-Sw for rsgb_lf_group@blacksheep.org; Wed, 07 Oct 2009 21:21:08 +0100 Received: from bb-87-82-8-19.ukonline.co.uk ([87.82.8.19] helo=[192.168.0.2]) by smarthost1.mail.uk.easynet.net with esmtp (Exim 4.69) (envelope-from ) id 1Mvd1j-000NBd-Th for rsgb_lf_group@blacksheep.org; Wed, 07 Oct 2009 21:22:24 +0100 Message-ID: <4ACCEA49.9030607@ukonline.co.uk> Date: Wed, 07 Oct 2009 20:21:45 +0100 From: Peter Dodd User-Agent: Thunderbird 2.0.0.23 (Windows/20090812) MIME-Version: 1.0 To: rsgb_lf_group@blacksheep.org References: <57a24ca70910070818o2e4adde4k1c8daa318eb2eb30@mail.gmail.com> <006001ca4763$a69a1290$0301a8c0@mal769a60aa920> <002601ca4766$1ff29bb0$6c01a8c0@DELL4> <4ACCD7FA.5080501@ukonline.co.uk> <4ACCB110.8A4E.00FD.0@globalstar.com> In-Reply-To: <4ACCB110.8A4E.00FD.0@globalstar.com> X-Karma: unknown: X-Spam-Score: 0.0 (/) X-Spam-Report: autolearn=disabled,none Subject: Re: LF: Re Propagation report Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit 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=none 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) David, There is a whole lot of stuff written about determining ERP involving a lot of maths. The most accurate method is to measure the actual field strength. These methods are described in 'LF Today' and 'The Low Frequency Experimenter's Handbook' available from ARRL Books (look in RSGB section). Also check out QST Nov 1998 and you will see the antenna I am using. My unconventional method of working out ERP is to calculate antenna gain (loss) using EZNEC. Because the radiation R is so low much of the gain is determined by the ground characteristics. This parameter I determine by measuring the RF current on the real antenna which is input into the model. My present antenna has a gain of around -12dBi. I trust this helps Peter Dodd, G3LDO > > As an interested observer from the other side of the pond, how do you > determine that you are close to the ERP limit?? I'd be interested in > knowing as I am trying to do some pro-bono work for the ARRL on > getting use of 137 kHz here in the USA. > > Tnx & 73, > > David Weinreich > WA2VUJ/3 > > >>> > *From: * Peter Dodd > *To:* > *Date: * 10/07/09 3:09 PM > *Subject: * LF: Re Propagation report > > Hi Jay, > I will be sending a beacon signal QRSS3 on 501.1kHz until 2330z. > I have modified my old PL519 TV sweep tube transmitter which ran about > 60 to 70W. It now has two PL519s in parallel running 120W. > I have taken down the HF quad until the sunspots wake up a bit and > reinstalled the antenna used for 73/136kHz so I am now running close to > the new ERP limit. > > > Peter, G3LDO >