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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