Return-Path: Received: from mtain-da04.r1000.mx.aol.com (mtain-da04.r1000.mx.aol.com [172.29.64.76]) by air-mc02.mail.aol.com (v129.4) with ESMTP id MAILINMC023-a8d54c62598515b; Wed, 11 Aug 2010 04:04:21 -0400 Received: from post.thorcom.com (post.thorcom.com [193.82.116.20]) by mtain-da04.r1000.mx.aol.com (Internet Inbound) with ESMTP id 96C6E38000493; Wed, 11 Aug 2010 04:04:10 -0400 (EDT) Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1Oj6Fk-0000RF-G0 for rs_out_1@blacksheep.org; Wed, 11 Aug 2010 09:01:36 +0100 Received: from [193.82.116.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1Oj6Fj-0000R6-VP for rsgb_lf_group@blacksheep.org; Wed, 11 Aug 2010 09:01:35 +0100 Received: from mail-bw0-f43.google.com ([209.85.214.43]) by relay1.thorcom.net with esmtp (Exim 4.63) (envelope-from ) id 1Oj6Fi-00009K-Md for rsgb_lf_group@blacksheep.org; Wed, 11 Aug 2010 09:01:35 +0100 Received: by bwz11 with SMTP id 11so2989458bwz.16 for ; Wed, 11 Aug 2010 01:01:32 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=domainkey-signature:mime-version:received:received:in-reply-to :references:date:message-id:subject:from:to:content-type; bh=RmGbZjszhohzOv1dx+ECYLkDT7nlbY66dSO7ikfiBLE=; b=Vvuu0fguDCBGSQpIEiSZoypheSwZuWXUhc9tDqdb7XCtl2zeNBbB/C1XTXb+7T24uH qqGkFbjcjjSJ+EuMFdqnQHjBAvXQJHaGb0YAHMdO8qmeLGE051k6EZ2WsIozwQhQ0Lg/ w67qhT4a2xJndtpg575vSVLWx5965lIZbwuDs= DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :content-type; b=Sybcv4p2PJfN5QqtChIUlXp1KHabMhmnalY0lIeHnqYLM0C1WWGNFiwMawDr/8uEAp +DNTrsN+AvFswy2e73J8hy5zWyYD94r4hO9t3KRxNjIvkiYDreoMAYJzyA3DEk8vbSA3 FcsNrwV6X51zTdpAcmpbnerH/STWltoq8quyQ= MIME-Version: 1.0 Received: by 10.204.47.38 with SMTP id l38mr4984951bkf.154.1281513692472; Wed, 11 Aug 2010 01:01:32 -0700 (PDT) Received: by 10.204.194.69 with HTTP; Wed, 11 Aug 2010 01:01:32 -0700 (PDT) In-Reply-To: <009101cb38dc$f0b119d0$4001a8c0@lark> References: <009101cb38dc$f0b119d0$4001a8c0@lark> Date: Wed, 11 Aug 2010 09:01:32 +0100 Message-ID: From: Roger Lapthorn To: rsgb_lf_group@blacksheep.org DomainKey-Status: good (testing) X-Spam-Score: 0.0 (/) X-Spam-Report: autolearn=disabled,HTML_MESSAGE=0.001 Subject: Re: LF: Re: 136kHz ERP calculation Content-Type: multipart/alternative; boundary=0016e6d77e7b6a2a28048d87a8e1 X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on post.thorcom.com X-Spam-Level: X-Spam-Status: No, hits=0.5 required=5.0 tests=HTML_20_30,HTML_MESSAGE 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-global-disposition: G x-aol-sid: 3039ac1d404c4c62597a4823 X-AOL-IP: 193.82.116.20 X-AOL-SPF: domain : blacksheep.org SPF : none X-Mailer: Unknown (No Version) --0016e6d77e7b6a2a28048d87a8e1 Content-Type: text/plain; charset=ISO-8859-1 Hi Alan, Thanks - that's obviously the thing to do. I'll try this later today and share results here. 73s Roger G3XBM On 10 August 2010 23:39, Alan Melia wrote: > Hi Roger you can calibrate your loop first using DCF39 on 138.83. This has > a > field strength in our area of 1mV/m. Then you could work back your own ERP > by comparison...... 1W ERP produces 300mV/m at 1km, 100mV/m at 10km (from > memory ....I think that is correct....10dB per decade after 1km). Doing it > that way removes as lot of the variables, and its a good thumbnail > calculation. > > Alan G3NYK > > ----- Original Message ----- > From: "Roger Lapthorn" > To: ; > Sent: Tuesday, August 10, 2010 7:09 PM > Subject: LF: 136kHz ERP calculation > > > > *My last post didn't appear, so this is a retry...* > > > > About a week ago I recorded my 136kHz QRP beacon (2W from PA, QRSS3, > using > > just 20m separated earth electrodes as the antenna) at 14.9km away from > the > > QTH using Spectran with a 30t, 80cm loop, Hi-Z matching into the FT817. > > > > I'm wondering if someone here is able to *work out the ERP* that I must > be > > achieving please. These are the numbers I have: > > > > Spectran signal level -42.5dB > > Resolution 0.17Hz > > Sampling rate 11025 > > Distance (Rx from TX) 14.9km > > > > It surprises me that the signal can be seen so well at this distance with > > such low power and with this "antenna" set-up. Thanks in advance for any > > help and please excuse my ignorance. > > > > 73s > > Roger G3XBM > > > > -- > > http://g3xbm-qrp.blogspot.com/ > > http://www.g3xbm.co.uk > > http://www.youtube.com/user/g3xbm > > G3XBM GQRP 1678 ISWL G11088 > > > > > -- http://g3xbm-qrp.blogspot.com/ http://www.g3xbm.co.uk http://www.youtube.com/user/g3xbm G3XBM GQRP 1678 ISWL G11088 --0016e6d77e7b6a2a28048d87a8e1 Content-Type: text/html; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable Hi Alan,
=A0
Thanks - that's obviously the thing to do. I'll= try this later today and share results here.

73s

Roger G3X= BM

On 10 August 2010 23:39, Alan Melia= <alan.m= elia@btinternet.com> wrote:
Hi Roger you ca= n calibrate your loop first using DCF39 on 138.83. This has a
field strength in our area of 1mV/m. Then you could work back your own ERP=
by comparison...... 1W ERP produces 300mV/m at 1km, 100mV/m at 10km (from<= br> memory ....I think that is correct....10dB per decade after 1km). =A0Doing= it
that way removes as lot of the variables, and its a good thumbnail
calculation.

Alan G3NYK

----- Original Message -----
From: "Roger Lapthorn" <rogerlapthorn@gmail.com>
To: <rsgb_lf_group@blac= ksheep.org>; <rogerla= pthorn@gmail.com>
Sent: Tuesday, August 10, 2010 7:09 PM
Subject: LF: 136kHz ERP calculation


> *My last post didn't appear, so this is a retry...*
>
> About a week ago I recorded my 136kHz QRP beacon (2W from PA, QRSS3,= using
> just 20m separated earth electrodes as the antenna) at 14.9km away fr= om
the
> QTH using Spectran with a 30t, 80cm loop, Hi-Z matching into the FT81= 7.
>
> I'm wondering if someone here is able to *work out the ERP* that= I must be
> achieving please. These are the numbers I have:
>
> Spectran signal level =A0 =A0 -42.5dB
> Resolution =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A00.17Hz
> Sampling rate =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A011025
> Distance (Rx from TX) =A0 =A014.9km
>
> It surprises me that the signal can be seen so well at this distance= with
> such low power and with this "antenna" set-up. =A0Thanks in= advance for any
> help and please excuse my ignorance.
>
> 73s
> Roger G3XBM
>
> --
> http://g= 3xbm-qrp.blogspot.com/
> http://www.g3xbm= .co.uk
> http:= //www.youtube.com/user/g3xbm
> G3XBM =A0 GQRP 1678 =A0 =A0ISWL G11088
>





--
http://g3xbm-qrp.blogspot.com/<= br>http://www.g3xbm.c= o.uk
http://www= .youtube.com/user/g3xbm
G3XBM=A0=A0 GQRP 1678=A0=A0=A0 ISWL G11088<= br> --0016e6d77e7b6a2a28048d87a8e1--