Message-ID: <4D53D965.3090003@iup.uni-heidelberg.de>
Date: Thu, 10 Feb 2011 13:26:13 +0100
From: =?ISO-8859-1?Q?Stefan_Sch=E4fer?= <Stefan.Schaefer@iup.uni-heidelberg.de>
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To: rsgb_lf_group@blacksheep.org
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Subject: Re: LF: how to get ground rod ressitance low
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J=FCrgen,

Am 10.02.2011 09:23, schrieb Jurgen Bartels:
>   one the other hand I want a small
> rod that can be pulled out with ease in spring when the season is over.
>   =20
Which season is over in the spring? VLF? Or LF? Theoretically its never=20
over although the records are done in winther of course. If people stay=20
QRV it won't be over! :-)
> What resistance do you get usually and what size do you use?
>   =20
Well, the losses are not only due to the earth but also due to=20
surroundings such as trees and buildings. I do not measure the earth=20
losses between two earth rods since its difficult to calculate the=20
actual losses that will appear in a given antenna by that. So my loss=20
measurement include the surrounding losses. On LF i get about 15...20=20
Ohm. On VLF it was just 65 Ohm last sunday. I'm using a copper plate=20
0.2m x 25m x 0.01m and now 2 earth rods that can be seen here:=20
http://cgi.ebay.de/Erder-Staberder-1-5-Meter-DIN-50976-/400170116873?pt=3D=
Elektroversorgungen&hash=3Ditem5d2bff6709
> Stefan, you wrote yesterday that you got 65 ohms with your rod on sunday=
.
> That's still pretty high
>   =20
But not on VLF, as long as you don't live near the sea!
And i am /p, not at home where one has all the time of the world to=20
increase and increase the earth system and can start by using the mains=20
grid!

What is your earth loss resistance when transmitting on your LF antenna=20
and which antenna current do you achieve? Or don't you have a TX system=20
at all?

73, Stefan