Delivered-To: daveyxm@virginmedia.com Received: by 10.50.237.98 with SMTP id vb2csp45078igc; Tue, 28 Jan 2014 13:17:35 -0800 (PST) X-Received: by 10.66.188.203 with SMTP id gc11mr3782423pac.63.1390943855187; Tue, 28 Jan 2014 13:17:35 -0800 (PST) Return-Path: Received: from ng12-vm1.bullet.mail.gq1.yahoo.com (ng12-vm1.bullet.mail.gq1.yahoo.com. [98.136.219.144]) by mx.google.com with SMTP id kn7si16878875pbc.6.2014.01.28.13.17.34 for ; Tue, 28 Jan 2014 13:17:35 -0800 (PST) Received-SPF: pass (google.com: manual fallback record for domain of sentto-85080895-3603-1390943853-daveyxm=virginmedia.com@returns.groups.yahoo.com designates 98.136.219.144 as permitted sender) client-ip=98.136.219.144; Authentication-Results: mx.google.com; spf=pass (google.com: manual fallback record for domain of sentto-85080895-3603-1390943853-daveyxm=virginmedia.com@returns.groups.yahoo.com designates 98.136.219.144 as permitted sender) smtp.mail=sentto-85080895-3603-1390943853-daveyxm=virginmedia.com@returns.groups.yahoo.com; dkim=pass header.i=@yahoogroups.co.uk DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=yahoogroups.co.uk; s=oscaro; t=1390943854; bh=CEpC8dNCjIg5B3TbQCWdWwEQFEuru/m2TTSiWds2tfw=; h=Received:Received:X-Yahoo-Newman-Id:X-Sender:X-Apparently-To:X-Received:X-Received:X-Received:X-Received:X-Received:X-Received:Message-ID:To:References:In-Reply-To:X-Priority:X-MSMail-Priority:X-Mailer:X-MimeOLE:x-aol-global-disposition:x-aol-sid:X-AOL-IP:X-Originating-IP:X-eGroups-Msg-Info:From:X-Yahoo-Profile:Sender:MIME-Version:Mailing-List:Delivered-To:List-Id:Precedence:List-Unsubscribe:Date:Subject:Reply-To:X-Yahoo-Newman-Property:Content-Type; b=gi877ccNMap3d3ohGgyttnwC2LsA2D4i91etLI2gu4Wt9BPv6Si0b0rOOpNVqfbMFEsCm6AXf/VCIAj2gq83HYSzuh3HJsUh1pqxWC5kTMPDwj8d4SMSoqmvEMlp5MRPz825jllGz40MktrH6JGGPAS/67lUyfwu53vh8pKAleU= DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws; s=oscaro; d=yahoogroups.co.uk; b=rPNqTY50s/fmgt27/E8VqgFvdyxb/ZTb/S9YJGZHF4VWwre1pMdBWA8p+5cx+J8KV2tI8ZAau7vFfRvj74wRq8PbiyZz1NEDEf7UMnr+00XFbVHCvdgYi4lrYoZ2P3VFwqTFgx+8I92SS+sXUGi1TdMWvFaP3hm4gmMtex1mtJ8=; Received: from [98.137.0.82] by ng12.bullet.mail.gq1.yahoo.com with NNFMP; 28 Jan 2014 21:17:34 -0000 Received: from [10.193.39.6] by tg2.bullet.mail.gq1.yahoo.com with NNFMP; 28 Jan 2014 21:17:34 -0000 X-Yahoo-Newman-Id: 85080895-m3603 X-Sender: markusvester@aol.com X-Apparently-To: rsgb_lf_group@yahoogroups.co.uk X-Received: (qmail 87465 invoked by uid 102); 28 Jan 2014 21:17:33 -0000 X-Received: from unknown (HELO mtaq5.grp.bf1.yahoo.com) (10.193.84.36) by m3.grp.bf1.yahoo.com with SMTP; 28 Jan 2014 21:17:33 -0000 X-Received: (qmail 7280 invoked from network); 28 Jan 2014 21:17:33 -0000 X-Received: from unknown (HELO omr-m04.mx.aol.com) (64.12.143.78) by mtaq5.grp.bf1.yahoo.com with SMTP; 28 Jan 2014 21:17:33 -0000 X-Received: from mtaout-mba01.mx.aol.com (mtaout-mba01.mx.aol.com [172.26.133.109]) by omr-m04.mx.aol.com (Outbound Mail Relay) with ESMTP id 2DB6F7000008F; Tue, 28 Jan 2014 16:17:33 -0500 (EST) X-Received: from Black (95-91-238-155-dynip.superkabel.de [95.91.238.155]) by mtaout-mba01.mx.aol.com (MUA/Third Party Client Interface) with ESMTPA id 7F1F2380000B2; Tue, 28 Jan 2014 16:17:32 -0500 (EST) Message-ID: To: , References: <8D0EA6E42A6D7DA-864-21682@webmail-m150.sysops.aol.com> In-Reply-To: <8D0EA6E42A6D7DA-864-21682@webmail-m150.sysops.aol.com> X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Windows Mail 6.0.6002.18197 X-MimeOLE: Produced By Microsoft MimeOLE V6.0.6002.18463 x-aol-global-disposition: G x-aol-sid: 3039ac1a856d52e81e6c660e X-AOL-IP: 95.91.238.155 X-Originating-IP: 10.193.84.36 X-eGroups-Msg-Info: 1:12:0:0:0 From: "Markus Vester" X-Yahoo-Profile: df6nm Sender: rsgb_lf_group@yahoogroups.co.uk MIME-Version: 1.0 Mailing-List: list rsgb_lf_group@yahoogroups.co.uk; contact rsgb_lf_group-owner@yahoogroups.co.uk Delivered-To: mailing list rsgb_lf_group@yahoogroups.co.uk List-Id: Precedence: bulk List-Unsubscribe: Date: Tue, 28 Jan 2014 22:17:30 +0100 Subject: [rsgb_lf_group] Re: LF: 73kHz in the UK? Reply-To: rsgb_lf_group@yahoogroups.co.uk X-Yahoo-Newman-Property: groups-email-ff-m Content-Type: multipart/alternative; boundary="----=_NextPart_000_0005_01CF1C76.BBE724C0" ------=_NextPart_000_0005_01CF1C76.BBE724C0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Correction: As Andy pointed out before, lambda/2pi is not 0.8 km but more l= ike 0.65 km. That will put on another 3.6 dB, resulting in 260 nW ERP. This assumes the prescribed fieldstrength is measured at a 10m radius from = a small magnetic source. Maybe one could cheat: Use a real long wire, and t= ake the distance only from the nearest point of the wire. Then you could ru= n 4 mA/m * 2pi * 10 m =3D 0.25 A up any length you want. Now that can be m= uch stronger ;-) 73, Markus =20 ----- Original Message -----=20 From: Markus Vester=20 To: rsgb_lf_group@blacksheep.org ; rsgb_lf_group@yahoogroups.co.uk=20 Sent: Tuesday, January 28, 2014 7:31 PM Subject: Re: LF: 73kHz in the UK? Hi Roger, calculating ERP... Using 1/r^3 from 10 m to the radiation field boundary at 0.8 km, we get +72 - 3 * 38 dBuA/m =3D -42 dBuA/m, then proceeding with 1/r to 1 km and multiplying by 377 ohms H =3D -42 - 2 =3D -44 dBuA/m, E =3D 7.5 dBuV/m, deriving radiated power and ERP EMRP =3D 7.5 - 49.5 =3D -42 dBm =3D 63 nW, ERP =3D 115 nanowatts. ... not much is it?=20 Anyhow using very slow modes, you might be able to make several tens or eve= n 100 kilometers on daytime groundwave. Best 73, Markus (DF6NM) -----Urspr=C3=BCngliche Mitteilung-----=20 Von: Roger Lapthorn An: rsgb_lf_group ; rsgb_lf_group Verschickt: Di, 28 Jan 2014 12:28 pm Betreff: LF: 73kHz in the UK? Is my reading of the UK frequency allocation chart right?=20 One can operate without a licence in the old 73kHz band using licence-exemp= t inductive devices rules as long as the output is less than 72dBuA at 10m?= Not sure what sort of ERP this equates to. A few uW I assume? Perhaps someone can advise/confirm. 73s Roger G3XBM ------=_NextPart_000_0005_01CF1C76.BBE724C0 Content-Type: text/html; charset=UTF-8 Content-Transfer-Encoding: quoted-printable  
=20=20=20=20=20=20 =20=20=20=20=20=20

=EF=BB=BF

Correction: As Andy pointed out before= , lambda/2pi=20 is not 0.8 km but more like 0.65 km. That will put on another 3.6 dB,=20 resulting in 260 nW ERP.
 
This assumes the prescribed fieldstren= gth is=20 measured at a 10m radius from a small magnetic source. Maybe one could=20 cheat: Use a real long wire, and take the distance only from the= =20 nearest point of the wire. Then you could run 4 mA/m *  2pi * 10 = m =3D=20 0.25 A up any length you want. Now that can be much stronger=20 ;-)
 
73, Markus
 
 
----- Original Message -----=20
From: Markus Vester=20
Sent: Tuesday, January 28, 2014 7:31 PM
Subject: Re: LF: 73kHz in the UK?

Hi Roger,
 
calculating= =20 ERP...
 
Using 1/r^3= from=20 10 m to the radiation field boundary at 0.8 km, we get
 += 72 - 3 *=20 38 dBuA/m =3D -42 dBuA/m,
then=20 proceeding with 1/r to 1 km and multiplying by 377 ohms
 H =3D= -42 - 2=20 =3D -44 dBuA/m, E =3D 7.5 dBuV/m,
deriving ra= diated=20 power and ERP
 EMRP= =20 =3D 7.5 - 49.5 =3D -42 dBm =3D 63 nW,
 ERP = =3D 115=20 nanowatts.
 
... not muc= h is=20 it?
 
Anyhow usin= g very=20 slow modes, you might be able to make several tens or even 100 kilometers o= n=20 daytime groundwave.
 
Best 73,
Markus=20 (DF6NM)
 
 

-----Urspr=C3=BCngliche Mitteilung-----
Von: Roger=20 Lapthorn <rogerlapthorn@gmail.com>
An: rsgb_lf_group=20 <rsgb_lf_group@blacksheep.org>; rsgb_lf_group=20 <rsgb_lf_group@yahoogroups.co.uk>
Verschickt: Di, 28 Jan 2014 12:2= 8=20 pm
Betreff: LF: 73kHz in the UK?


Is my reading of the UK frequency allocation c= hart=20 right?

One can operate without a licence in the old 73kHz ba= nd=20 using licence-exempt inductive devices rules as long as the output is less = than=20 72dBuA at 10m? Not sure what sort of ERP this equates to. A few uW I=20 assume?

Perhaps someone can=20 advise/confirm.

73s
Roger G3XBM

 

=20=20=20=20=20
__._,_.___
=20=20=20=20=20=20=20=20 =20=20 =20=20=20 =20
Recent Activity: =20=20=20=20
=20=20
3D"Yahoo!
Switch to: Text-Only, Daily Digest= • Unsubscribe • <= a href=3D"http://info.yahoo.com/legal/uk/yahoo/utos/en-gb/details.html" sty= le=3D"text-decoration: none;">Terms of Use
.
=
__,_._,___
------=_NextPart_000_0005_01CF1C76.BBE724C0--