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Stefan's test signal seems to be visible here
in the decreasing QRN level. Frequency slightly variable just
below 8969.98, now about 10 dB SNR.
Best 73,
Markus (DF6NM)
Sent: Friday, June 10, 2011 6:36 PM
Subject: Re: LF: Re: First tests on VLF at DK7FC in
Heidelberg
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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