Hi Lubos,
Am 06.11.2011 14:06, schrieb Lubos OK2BVG:
I am going to improve some parts of my "kite equipment". I would
like to be ready when the wind is good!
And what do you inted to improve?
I see you are one of the real practical amateurs and build a fine
equipment (like S52AB too) so maybe an automatic variometer would be a
nice project to maximise the ERP in each kite angle. The lower the
losses, the smaller the antenna BW and so the stronger the power
decrease as a result of a changing kite angle. The radiation resistance
is then strongly decreasing too, you know, but at least so can push the
maximum power into the system anyway.
On my QTH the wind is often stable. I think this is the reason why they
installed the wind power plants there. Thus i have no automatic
variometer there. Also i am regulating the TX power by tuning to
resonance, always beeing a bit beside the top of the resonance curve.
When i tune to the top, my generator stops, unfortunately ;-) Normally
i am getting about 1 A +- 0.2 A antenna current on 8970 Hz. But as i
did CW and used the 60000 uF (@350 V DC) cap in parallel
(http://dl.dropbox.com/u/19882028/DSC03414.JPG) i got a maximum antenna
current of 1.7 A :-) That's a factor 3 in power, so almost 5 dB
improvement, another advantage of fast CW! :-)
What is the S/N of your signal on your own grabber? Maybe you can make
an audio recording and listen to your own signal after the test, just
for the fascination of real CW on VLF! :-) Remember my own CW signal in
40.0 km distance (far field):
http://dl.dropbox.com/u/19882028/DK7FCinCWon8970Hzthe33kmband.WAV
I hope i can come back soon on the band. It just depends on the wind
and absence of rain on a weekend but that isn't so easy in the last
time...
73 es GL!
Stefan/DK7FC
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