Hello Victor, LF,
It took a little bit to reply to your answer. You have been absolutely
right! DLF(153kHz) is here just some 10km away and the strong french LF
broadcast station on 162kHz has caused the nonlinear working of my
first stage i assume. Yesterday i talked with Markus/DF6NM and he gave
me the very useful hint to add a C between drain and gnd of the first
stage (what forms a low pass with the drain R). Before some minutes i
added a 100nF capacitor, so the edge frequency should be about 15kHz.
Before that, i have looked on a second experimental active E field
antenna how it influences the gain on the dreamers band (almost no
difference). But see the S/N improvement NOW on my grabber
(http://www.iup.uni-heidelberg.de/schaefer_vlf/DK7FC_VLF_Grabber.html)!
What a big difference!!! :-)))))
So happy about that! :-)
Tnx to Markus and you, Victor!
73, Stefan/DK7FC
PS: I have built a small TX antenna at my new home QTH in Heidelberg.
With a TV transformer and my 300W PA (running at 15W DC input) i apply
about 2kV rms on a 10m horizontal wire, about 3m above gnd. The
distance to the grabber here is 1,1km. Hopefully i can see something,
at least in DFCW-600...
Am 28.04.2010 15:51, schrieb [email protected]:
Hi Stefan,
looks nice but I suspect you have some im
problem in your first stage because off the strong line at 9 KHz,Maby
it's better to use a filter at the input....
73
Victor
Dear LF,
Daniele and others asked for the circuit of my active E field antenna
that i am using for my grabber. Now i have created a pdf file where you
can find the circuit and a picture of the arrangement and a spectrogram
of the currently working circuit.
http://www.iup.uni-heidelberg.de/schaefer_vlf/8,97kHz%20active%20E%20field%20antenna%20by%20DK7FC.pdf
So, if you are interested or want to get some ideas for your own
circuit, take a look on it. I hope the link works.
So, best 73 and maybe cu this evening there, dreamers.
Stefan/DK7FC
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