Return-Path: Received: from mtain-mg03.r1000.mx.aol.com (mtain-mg03.r1000.mx.aol.com [172.29.96.203]) by air-da04.mail.aol.com (v129.10) with ESMTP id MAILINDA043-863c4dbd340a35; Sun, 01 May 2011 06:20:58 -0400 Received: from post.thorcom.com (post.thorcom.com [195.171.43.25]) by mtain-mg03.r1000.mx.aol.com (Internet Inbound) with ESMTP id 07EF638000089; Sun, 1 May 2011 06:20:56 -0400 (EDT) Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1QGTkU-0001TA-La for rs_out_1@blacksheep.org; Sun, 01 May 2011 11:19:34 +0100 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1QGTkT-0001T1-Kz for rsgb_lf_group@blacksheep.org; Sun, 01 May 2011 11:19:33 +0100 Received: from nm18.bullet.mail.ukl.yahoo.com ([217.146.183.192]) by relay1.thorcom.net with smtp (Exim 4.63) (envelope-from ) id 1QGTkT-00059G-HH for rsgb_lf_group@blacksheep.org; Sun, 01 May 2011 11:19:33 +0100 Received: from [217.146.183.217] by nm18.bullet.mail.ukl.yahoo.com with NNFMP; 01 May 2011 10:19:28 -0000 Received: from [217.146.183.60] by tm10.bullet.mail.ukl.yahoo.com with NNFMP; 01 May 2011 10:19:27 -0000 Received: from [127.0.0.1] by omp1029.mail.ukl.yahoo.com with NNFMP; 01 May 2011 10:19:27 -0000 X-Yahoo-Newman-Property: ymail-3 X-Yahoo-Newman-Id: 964894.43285.bm@omp1029.mail.ukl.yahoo.com Received: (qmail 95611 invoked by uid 60001); 1 May 2011 10:19:27 -0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=yahoo.co.uk; s=s1024; t=1304245167; bh=tkBQ2dZGSR4LwB75KmCgaV3gpTXY99Pckbag6poEJTc=; h=Message-ID:X-YMail-OSG:Received:X-Mailer:References:Date:From:Subject:To:In-Reply-To:MIME-Version:Content-Type; b=TVS3ovkkvM7HLpnwXPooZZyGugdF9v3dhBUgg4TquXoP/aZ3pT6Fz1uwvJv20xs9tRN7Eme3Td7RNrnoErDgvP8Wu5HAN1rbOWrgVRHyULHy/pORLPuky4Mi+pryhzbjwxO3XnfcD0Nt0K24BRrWX/NZznlzYtro+0c7HzZnDo8= DomainKey-Signature:a=rsa-sha1; q=dns; c=nofws; s=s1024; d=yahoo.co.uk; h=Message-ID:X-YMail-OSG:Received:X-Mailer:References:Date:From:Subject:To:In-Reply-To:MIME-Version:Content-Type; b=hUSAx9VboFMHMe29HQOvBzg6UkgmfPqRe8bi8t3uWZkKYMNPMArlhDwbb2PgkZpEfA+YsQbqFhyt3Y7q44Z0S3bzhy+K3/lCH4+J57m6Gpb57mfKajs25eu3OcatLM2b6+A2ebaAJMBLc1Ua71STeseckEFZvpl1lJmqJhVdVcw=; Message-ID: <707765.95482.qm@web28101.mail.ukl.yahoo.com> X-YMail-OSG: IH2FhxwVM1lXY6zdLsjKsdKl78dUCLKZhcSHEXLZnW5Ofg1 C2_uc8S7F47Lv4Cq1teK5mkLt72_KIy7KZzxkcEv1vvi4IGxJ9UQMbXlQGpx nyL_c2EnZt65xgA9LfS9oedUIErzwhoTYPehOpp.XMIkDu0tK1GCpvUtJwxW 3p6It91WIQKOiZ4vCcVnzfMj2_RkYBOrp2gVUG1et5agnnu2JOIrg41kH4YT _eQK7XLdXTF8.nfc0sQYedoaLHZMGUHq9w4CfAb_Pftkyd3L0x1gAG.60G10 9fNetUFyue9yYPmB6w5OUTKZPW9FFDmcfAJRpSecHQx4FUPzjcbi4QNSPYQ- - Received: from [86.134.236.136] by web28101.mail.ukl.yahoo.com via HTTP; Sun, 01 May 2011 11:19:27 BST X-Mailer: YahooMailRC/559 YahooMailWebService/0.8.110.299900 References: Date: Sun, 1 May 2011 11:19:27 +0100 (BST) From: M0FMT To: rsgb_lf_group@blacksheep.org In-Reply-To: MIME-Version: 1.0 DomainKey-Status: good (testing) Subject: Re: LF: ERP estimation Content-Type: multipart/alternative; boundary="0-667856721-1304245167=:95482" X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on post.thorcom.com X-Spam-Level: X-Spam-Status: No, hits=0.8 required=5.0 tests=HTML_30_40,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-SCOLL-AUTHENTICATION: mail_rly_antispam_dkim-m022.1 ; domain : yahoo.co.uk DKIM : pass x-aol-sid: 3039ac1d60cb4dbd3408544e X-AOL-IP: 195.171.43.25 X-AOL-SPF: domain : blacksheep.org SPF : none --0-667856721-1304245167=:95482 Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: quoted-printable Hi Andy and LF There must be some software written that does this?=20 =A073 es GL Pete M0FMT IO91UX=20 ________________________________ From: Andy Talbot To: rsgb_lf_group@blacksheep.org Sent: Sun, 1 May, 2011 10:07:13 Subject: LF: ERP estimation You cannot calculate ERP directly from Transmit power without also obtaini= ng an=20 estimate of the additional losses, mainly caused by ground resistance.=A0= =A0 You=20 must have either the RMS RF current in the vertical, OR teh total series= loss=20 resistance of the actual vertical system,=A0before any Tx matching that ma= y be in=20 place. If you can measure RF current in the vertical, that will give you ERP=20 directly=A0from Ohms law on the=A0Radiation resistance (which is directly= related=20 to=A0the effective height of the antenna). =A0=A0=A0=A0 ERP =3D I^2 * 3200 * (Heff / lambda) ^ 2=A0=A0=A0=A0=A0=20 For a vertical with no top hat, Heff =3D half the effective height.=A0=A0 If you were to have an infinite top hat, Heff =3D actual height.=A0=A0=A0= =20 For most practical antennas use a value about half way, so a resonable=20 approximation is given by : =A0=A0=A0=A0 ERP =3D I^2 * 1600 * (H / lambda)^2 Another way is to measure your total load resistance in series with the=20 antenna,=A0 =3D Rloss Once you have this value, the efficiency is then given by Radiation resist= ance /=20 Rloss .=A0=20 Rrad ~=3D 1600 * (H/lambda)^2 as shown above.=A0 So ERP =3D=A0=A0 Tx power= * Rrad / Rloss Andy www.g4jnt.com =A0 On 30 April 2011 20:32, Luis EA3WX wrote: Hi Dennis, > >A question, please. I am beaconing on 502,25 KHz. My transmitter puts 35= W into=20 >a T antenna, high 20 m and an horizontal capacitor top of 10 m. > >With others ham fellows we are discussing what ERP I am sending, but we= have no=20 >results. Can you tell me how measure or are you calculating or estimating= this=20 >ERP? > >Thanks, 73 > >Luis, EA3WX=20 > >From: DENNIS EASTERLING=20 >Sent: Saturday, April 30, 2011 8:55 PM >To: rsgb_lf_group@blacksheep.org=20 >Subject: LF: Re: GB4FPR 502 KHZ INTERNATIONAL MARCONI DAY 30/4/2011=20 > >Hi Graham >=A0 >I tried sending to you 1630-1635 and 1940-1945 local times today Saturday= 30 04=20 >2011, but no reply.=A0=A0 I guess you could not hear me, or I you.=A0=A0= I send CW=20 >25watts into a 'T' aerial 20m top and 10m vertical.=A0=A0 Estimated erp= 250mW max.=A0=A0=20 >Anyway, I hope you had a good day with plenty of DX. >=A0 >73 Dennis M0JXM >=A0 --0-667856721-1304245167=:95482 Content-Type: text/html; charset=iso-8859-1 Content-Transfer-Encoding: quoted-printable
Hi Andy and LF
 
There must be some software written that does this?
 
7= 3 es GL Pete M0FMT IO91UX=20

=
From: Andy Talbot <andy= .g4jnt@gmail.com>
To: rsgb_lf_group@blacksheep.org
Sen= t: Sun, 1 May, 2011 10:07:13
Subject: LF: ERP estimation

You cannot calculate ERP directly from Transmit power without also ob= taining an estimate of the additional losses, mainly caused by ground resi= stance.   You must have either the RMS RF current in the vertica= l, OR teh total series loss resistance of the actual vertical system, = ;before any Tx matching that may be in place.
 
If you can measure RF current in the vertical, that will give you ERP= directly from Ohms law on the Radiation resistance (which is di= rectly related to the effective height of the antenna).
     ERP =3D I^2 * 3200 * (Heff / lambda) ^ 2&nbs= p;    
For a vertical with no top hat, Heff =3D half the effective height.&n= bsp; 
If you were to have an infinite top hat, Heff =3D actual height. = ;  
For most practical antennas use a value about half way, so a resonabl= e approximation is given by :
     ERP =3D I^2 * 1600 * (H / lambda)^2
 
Another way is to measure your total load resistance in series with= the antenna,  =3D Rloss
Once you have this value, the efficiency is then given by Radiation= resistance / Rloss . 
Rrad ~=3D 1600 * (H/lambda)^2 as shown above.  So ERP =3D &= nbsp; Tx power * Rrad / Rloss
 
Andy


 
On 30 April 2011 20:32, Luis EA3WX <shekina1@orange.es>= wrote:
Hi Dennis,
 
A question, please. I am beaconing on 502,25 KHz. My transmitter puts= 35 W into a T antenna, high 20 m and an horizontal capacitor top of 10 m.=
 
With others ham fellows we are discussing what ERP I am sending, but= we have no results. Can you tell me how measure or are you calculating or= estimating this ERP?
 
Thanks, 73
 
Luis, EA3WX
 
Sent: Saturday, April 30, 2011 8:55 PM
Subject: LF: Re: GB4FPR 502 KHZ INTERNATIONAL MARCONI DAY 30/4= /2011
 
Hi Graham
 
I tried sending to you 1630-1635 and 1940= -1945 local times today Saturday 30 04 2011, but no reply.   I guess you could not hear me, or I you.&n= bsp;  I send CW 25watts into a 'T' aerial 20m top and 10m vertical.&n= bsp;  Estimated erp 250mW max.   Anyway, I hope you had a= good day with plenty of DX.
 
73 Dennis M0JXM
 
=

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