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Hello
Stefan,lf
glad
to hear you solved the problem and your grabber is now much more sensitive,maby
some manmade signals will pop up...
I had
the same problem here with 675 KHz (7Km away) together with 1008 and 747
KHz,this gave products at 333 and 72 KHz..
73
Victor
PS
building a new ocxo controlled rx for lf,mf and topband,single conversion with
1.4MHz if.
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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