Congratulations Stephan
I am following (dreaming) with interest. My RX set up is not wonderful but I
shall be there when you announce a test, you never know.
Just the kite flying will be fun.
Eddie G3ZJO
-----Original Message-----
From: Stefan Schäfer [mailto:[email protected]] On Behalf
Of Stefan Schäfer
Sent: 29 June 2010 00:13
To: [email protected]
Cc: [email protected]
Subject: VLF: Extreme Dreaming: Announcement for the 47 km band :-)
Dear VLF,
Today i have got the official permission of the german authorities for a
kite vertical antenna up to 300 m above ground! :-))
This permission is time limited to the 30th June 2012, which is a pretty
long time :-))))) Also, is limited to the location where i was QRV in the
last experiments (JN49IS).
On each test (that MUST be during the daylight!) i have to inform the german
air-traffic control. This can be done by a telephone call, so no problem.
The owner of the kite store told me that there are 200m long braids for such
kites available. So, when using a 300 m vertical antenna i will add this
braid to the 100 m braid that i am using all the time.
When transmitting with that antenna on 8,97 kHz i have to reduce the L since
my C is abt 3 times higher. But to get experience with such huge
constructions i will start just using a 200m vertical without changing the
L. This is a first step. My 600 W PA will have no problem with QSY since it
is a H bridge without an output transformer. It can itdown do DC ;-)
Having twice the C without changing the L (later i will reduce it to come
back to 8,97) will result in a resonance frequency of 8,97/sqrt(2) is about
6,34 kHz, the 47,3 km band. When applying 500W i suppose to radiate an ERP
of 16 mW!! In my 2nd test that was received by Paul Nicholson it was 1,7 mW,
so about 10 dB more in the next test. The exact frequency has to be found in
some measurements and is caused by the real resonance of the system. So 6,34
kHz is just a number. But since i have the 30 mH variometer i am sure to
make it adjustable within a range of some Hz.
Let's see what can be achieved with such an antenna on that frequency.
There were at least 10 RX stations who demonstated to have most suitable VLF
RX possibilities in the last tests!Who of those (and others) are interested
to try an attempt to receive such a signal in good old DFCW-600 ?
This will be an exciting summer/autumn/winter, isn't it? Also on 137 kHz
;-)... *amhappy*
73, Stefan/DK7FC
PS: If using 300m i will come down to 5,18 kHz, the 58 km band ;-) ...and
having 32 mW ERP
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