Message-ID: <4DF24806.7030508@iup.uni-heidelberg.de>
Date: Fri, 10 Jun 2011 18:36:22 +0200
From: =?ISO-8859-15?Q?Stefan_Sch=E4fer?= <Stefan.Schaefer@iup.uni-heidelberg.de>
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To: rsgb_lf_group@blacksheep.org
CC: Paul <paul@abelian.netcom.co.uk>, Bernd Grupe <bernd.grupe@t-online.de>
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Subject: Re: LF: Re: First tests on VLF at DK7FC in Heidelberg
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After a break i am back on air in this moment transmitting a long=20
carrier. The signal generator is the DDS VFO, so stability is not=20
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,=20
the resonance is at 9.64 kHz, not to far away. I built a capacitor out=20
of 2 aluminium plates and 2 coca cola bottles and come to resonance now=20
on 8970 Hz. Before is used the bottles, i used stones. But they became=20
HOT and later there was a black hole into them sparking around! These=20
losses reduced the antenna power to less than 200 mA. Now i have about=20
500 mA antenna current and will transmit a longer dash until i see some=20
traces on the grabbers, hopefully.

When running the system without external addional C, so on 9.64 kHz, i=20
am getting 360 mA antenna current at 80 W PA input power. The coil=20
losses are 320 Ohm so the sourrounding losses seem to be about 300 Ohm=20
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 Sch=E4fer"<Stefan.Schaefer@iup.uni-heidelberg.de>
> To:<rsgb_lf_group@blacksheep.org>
> Cc: "Paul"<paul@abelian.netcom.co.uk>; "Bernd Grupe"
> <bernd.grupe@t-online.de>
> 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:
>   =20
>> 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 Sch=E4fer"<schaefer@iup.uni-heidelberg.de>
>> To:<rsgb_lf_group@blacksheep.org>
>> Cc: "Paul"<paul@abelian.netcom.co.uk>; "Bernd Grupe"
>> <bernd.grupe@t-online.de>
>> Sent: Thursday, June 09, 2011 8:09 PM
>> Subject: VLF: First tests on VLF at DK7FC in Heidelberg
>>
>>
>>
>>     =20
>>> VLF,
>>>
>>> Tomorrow i plan to do first tests on 8970 Hz on my fixed antenna in
>>> Heidelberg,
>>> http://no.nonsense.ee/qthmap/?qth=3DJN49IK00WG&from=3Djn49ik00WD 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 tha=
t
>>> 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 t=
o
>>> several 10 kV on the wire.
>>>
>>> Is there someone who will watch for that signal?
>>>
>>> Reports would be very apprechiated!
>>>
>>> 73, CU, Stefan/DK7FC
>>>
>>>
>>>       =20
>>     =20
>
>   =20