After a break i am back on air in this moment transmitting a long
carrier. The signal generator is the DDS VFO, so stability is not
perfect but should be suitable for 424 uHz i hope. It is a very first test.
When using the antenna wire with maximum L i currently have available,
the resonance is at 9.64 kHz, not to far away. I built a capacitor out
of 2 aluminium plates and 2 coca cola bottles and come to resonance now
on 8970 Hz. Before is used the bottles, i used stones. But they became
HOT and later there was a black hole into them sparking around! These
losses reduced the antenna power to less than 200 mA. Now i have about
500 mA antenna current and will transmit a longer dash until i see some
traces on the grabbers, hopefully.
When running the system without external addional C, so on 9.64 kHz, i
am getting 360 mA antenna current at 80 W PA input power. The coil
losses are 320 Ohm so the sourrounding losses seem to be about 300 Ohm
which is not to much, thinking about trees and buildings...
Now, i'll TX for some time, maybe 2 hours ort so.
Any reports so far?
73, Stefan/DK7FC
Am 10.06.2011 15:00, schrieb mal hamilton:
Stefan
My monitor is running/Speclab dfcw600 es Antenna 150 metre inv L up over 33
metres vertical. Condx all bands Good at present
de mal/g3kev
----- Original Message -----
From: "Stefan Schäfer"<[email protected]>
To:<[email protected]>
Cc: "Paul"<[email protected]>; "Bernd Grupe"
<[email protected]>
Sent: Friday, June 10, 2011 1:02 PM
Subject: Re: LF: Re: First tests on VLF at DK7FC in Heidelberg
Hello Mal, VLF,
OK, i am actually RX QRV on LF all the time here. And i have internet
during the test! :-)
Now, the coil is on the roof and it's dry. I will prepare now... Maybe
the first VLF antenna current in a 20 minutes...
73, Stefan/DK7FC
Am 10.06.2011 09:53, schrieb mal hamilton:
Stefan
I will leave my monitor on 8970 DFCW 600 mode. If I detect your signal I
will reply on 137.7 CW or QRS3.
73 De Mal/G3KEV
----- Original Message -----
From: "Stefan Schäfer"<[email protected]>
To:<[email protected]>
Cc: "Paul"<[email protected]>; "Bernd Grupe"
<[email protected]>
Sent: Thursday, June 09, 2011 8:09 PM
Subject: VLF: First tests on VLF at DK7FC in Heidelberg
VLF,
Tomorrow i plan to do first tests on 8970 Hz on my fixed antenna in
Heidelberg,
http://no.nonsense.ee/qthmap/?qth=JN49IK00WG&from=jn49ik00WD It is about
30m up.
I'll start doing some resonating tests and may come on air in the
afternoon. The small PA (max. 300W) will be used in this first test
since it is easier to manage. Maybe the resonance will be some kHz
higher but i hope to come down into the Dreamers Band (TM).
I expect to be visible on "local" grabbers like DF6NM, OE3GHB and
OK2BVG. If all works well i plan to transmit a longer dash, maybe 6000
seconds and later a short message in DFCW-600, like "K" or so, just for
the proof and to get a first impression about the efficiency of this
antenna.
I had the idea to buy some flexible aluminium tube to form a toroid that
will be placed on the top of the coil. Tis reduces the maximum E field
and adds some C, that might be needed to come down to 8970 Hz...
Of course all this depends on the absence of rain but now i don't need
wind! Therefore, the signals will be about 20 dB lower, probably.
The signal will be overload my grabber
http://www.iup.uni-heidelberg.de/schaefer_vlf/DK7FC_VLF_Grabber.html
that is in about 20 m (!) distance. Hopefully it gets not damaged due to
several 10 kV on the wire.
Is there someone who will watch for that signal?
Reports would be very apprechiated!
73, CU, Stefan/DK7FC
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