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Date: Sun, 6 Mar 2011 14:03:23 +0000
Message-ID: <AANLkTin-x8fUifD8ebyHTSyMqcG67kg1UZx6NZXioM3P@mail.gmail.com>
From: Roger Lapthorn <rogerlapthorn@gmail.com>
To: rsgb_lf_group@blacksheep.org, Chris Osborn <g3xiz@yahoo.co.uk>, 
	Eddie <g3zjo@talktalk.net>, M0JXM Dennis <dennis.easterling@btinternet.com>, 
	Pete <m0fmt@yahoo.co.uk>, James Cowburn <james.cowburn@virgin.net>
DomainKey-Status: good (testing) 
Subject: LF: G3XIZ's ERP on 9kHz (2uW)
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Today I did a quick calculation of Chris G3XIZ's ERP on 9kHz based on
information he has provided. I appreciate the accuracy is not great.

*Parameters*

Antenna type: Marconi with 10m vertical and 40m horizontal
Power: 100W RF out of the PA
Antenna current: 0.18A

*Rr (Radiation resistance) *= 160 x pi^2 x Heff^2 /lambda^2 .  For
simplicity, I have assume Heff is 5m. It might be a little better than this,
but not much at this wavelength.

So, Rr = (160 x 9.9 x 25) / (33000 x 33000) = 39600/1089 x 10E-6  = 36.36
uOhms

*ERP (for a Marconi)*  = 1.8 x I^2 x Rr = 1.8 x 0.0324 x 36.36 x 10E-6

*Therefore G3XIZ's ERP = 2.1 uW*

Clearly there are errors and uncertainties, but this gives an order of
magnitude.  Hope this is correct (I make lots of mistakes with sums) and of
interest.

73s
Roger G3XBM


-- 
g3xbm-qrp.blogspot.com/
www.g3xbm.co.uk
www.youtube.com/user/g3xbm
<http://vlf_grabber>G3XBM   GQRP 1678    ISWL G11088

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Today I did a quick calculation of Chris G3XIZ&#39;s ERP on 9kHz based on=
 information he has provided. I appreciate the accuracy is not great.<br><=
br><u><b>Parameters</b></u><br><br><div style=3D"margin-left: 40px;">Anten=
na type: Marconi with 10m vertical and 40m horizontal<br>
Power: 100W RF out of the PA<br>Antenna current: 0.18A<br></div><br><b>Rr=
 (Radiation resistance) </b>=3D 160 x pi^2 x Heff^2 /lambda^2 .=A0 For sim=
plicity, I have assume Heff is 5m. It might be a little better than this,=
 but not much at this wavelength.<br>
<br><div style=3D"margin-left: 40px;">So, Rr =3D (160 x 9.9 x 25) / (33000=
 x 33000) =3D 39600/1089 x 10E-6=A0 =3D 36.36 uOhms<br></div><br><b>ERP (f=
or a Marconi)</b>=A0 =3D 1.8 x I^2 x Rr =3D 1.8 x 0.0324 x 36.36 x 10E-6=
 <br><br><b>Therefore G3XIZ&#39;s ERP =3D <u>2.1 uW</u></b><br>
<br>Clearly there are errors and uncertainties, but this gives an order of=
 magnitude.=A0 Hope this is correct (I make lots of mistakes with sums) an=
d of interest.<br><br>73s<br>Roger G3XBM<br><br clear=3D"all"><br>-- <br><=
a href=3D"http://g3xbm-qrp.blogspot.com/" target=3D"_blank">g3xbm-qrp.blog=
spot.com/</a><br>
<a href=3D"http://www.g3xbm.co.uk" target=3D"_blank">www.g3xbm.co.uk</a><b=
r><a href=3D"http://www.youtube.com/user/g3xbm" target=3D"_blank">www.yout=
ube.com/user/g3xbm</a><br><a href=3D"http://vlf_grabber" target=3D"_blank"=
></a>G3XBM=A0=A0 GQRP 1678=A0=A0=A0 ISWL G11088<br>

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