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
|
