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Hello Horst.
Just clicked to open your pictures, but no pictures
appeared.
73
Ken
M0KHW
----- Original Message -----
Sent: Tuesday, May 11, 2010 9:45 AM
Subject: Re: LF: RE: 8,97 kHz active
antenna circuit and pictures
Hello Stefan,
TV Transformer, interesting. I think it should work
well on lower distance. QRP on 9kHz, hi. I also had this idea after my first
tests on 9kHz. I wanted to test it but my few TV transformers are DST and I
think I will need a flyback. The flybacks are common in the first generations
of tv sets up to the seventies but hard to get
nowadays.
I am not sure if the hoizontal antenna is the best
solution. As we know in theory there are more ground losses. But if this will
be of any significant influence at this low
frequencies?
I am looking foward to your tests
again.
BTW I am waiting for more motivating weather
conditions. I collected a few hundred meters of isolated military wire. After
confectioning it I will have material for an earthbase of about 800 to 1000 m.
This will be tested as soon as
possible.
Horst
Von: "Stefan Schäfer"
<[email protected]>
Gesendet: 10.05.2010
20:52:33
An: [email protected]
Betreff: Re:
LF: RE: 8,97 kHz active antenna circuit and pictures
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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