Message-ID: <4FC51B11.3010907@iup.uni-heidelberg.de>
Date: Tue, 29 May 2012 20:53:05 +0200
From: =?ISO-8859-15?Q?Stefan_Sch=E4fer?= <Stefan.Schaefer@iup.uni-heidelberg.de>
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References: <4FC39CF3.7020701@legal-medicine.de> <003a01cd3cee$0e74a1a0$1502a8c0@Clemens04> <4FC51191.8060004@legal-medicine.de>
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Subject: Re: LF: Re: VLF/LF-Preamp
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Hi Peter,

How sensitive is the balanced probe to shielding effects (trees, 
houses)? Any difference to the E field probe?
Where do you have the INA111 from?
What are the differences on 137 kHz? Is there a significant S/N improvement?

A nice design. The only problem i see the the availablility of the 
special parts. But lastly both are E field antennas and will react on 
man made noise coming from the near field. However it is an interesting 
alternative for those who cannot find a separate local ground for the LF 
antenna (e.g. living in a high house)...

73,Stefan/DK7FC

Am 29.05.2012 20:12, schrieb pws:
> Hi Clemens et al.
>
> Thanks for all those hints! Finally I think I've found it.
> It's somewhat trivial, should better write embarrassing (sic!).
>
> I used an old 9 Volts-block for testing. Since it ran out of
> voltage (<7 Volts) during the trials I changed over to a bundle
> of 8 AA-Cells. The effect now was nearly "invisible".
>
> Using a new 9 Volts-block it reappears but not such strong.
> Strange.
>
> Adding some capacitors right over that battery of AA-cells
> I have to knock very strongly now until the effect is discernable.
> Touching the battery does not show any further interferences.
>
> Made some screenshots, distance of both probes approx.
> 1 m (cave, big!).
>
> The old e-field probe running a BF981:
> http://www.df3lp.de/misc/rx/Left_BF981.png
> Images: http://df3lp.de/misc/rx/e-field_probe.png
>
> The new INA111 balanced probe:
> http://www.df3lp.de/misc/rx/Right_INA111.png
>
> Greetings from Kiel es tu,
> Peter, df3lp