Pse qsp to Stefan to SHOUT from his hill top and face DOWN wind for an
extra 23 dB. If all 9 DREAMERS face his direction records could be
broken without the KITE,
Do not break WIND to avoid QRM during the listening period.
G3KEV
----- Original Message -----
*From:* Markus Vester <mailto:[email protected]>
*To:* [email protected]
<mailto:[email protected]>
*Sent:* Sunday, February 28, 2010 12:48 PM
*Subject:* LF: Re: VLF TX experiments this sunday
Dear LF,
Stefan DK7FC just called me on the phone. He asked me to inform
the group that because of much heavier winds than expected, he
will not be able to transmit from the kite antenna today. He also
mentioned that the output matching of his PA (a converted SMPS
circuit) will require some more work.
Kind regards,
Markus (DF6NM)
----- Original Message -----
*From:* Stefan Schäfer <mailto:[email protected]>
*To:* [email protected]
<mailto:[email protected]>
*Sent:* Saturday, February 27, 2010 3:33 PM
*Subject:* LF: VLF TX experiments this sunday becomes more
probably
Dear LF group,
Tomorrow, the wind forecast is excellent! See
http://www.windfinder.com/forecast/frankfurt
It is almost to much wind but i have the new kite braid with a
strenght of 500kg... So the antenna will be in a high angle
and stable for tests. That is the first positive news.
Yesterday i got such a air coil. It has not 85mH but even
about 100mH but It's Q is bad at 8,9kHz, just about 38.
Anyway, i will easily handle 20kV rms. This will be the
maximum voltage on my single wire. There are several
possibilities to increase the maximum antenna voltage, well
known and applied in the high voltage power fields but this
may be very difficult at a kite antenna. So i will start with
a first test at only 20kV, if the PA will give a proper power ;-)
That coil is very heavy, about 50kg, really no fun to carry
that and there are better ways to realisethat. But it is
available i get the chance to resonate that 100m vertical at
8,9kHz. I tried to resonate it in the living room of my
parents since it it to heavy to carry it in my room in the
first floor ;-) It was successfully resonated with 6x22nF/6kV
plus a lower voltage C in series, about 33nF/2kV and a DDS VFO
with a sinus output, loosely coupled by another air coil (in
this way i will be able to make a transformation of the
resonated loop!(varying the coupling)). The 8,9kHz are well
audible so i am excited how the antenna and coil will sound
when some 100W applied;-)
The last problem is the PA since it is not yet available. I
will try to built it today or tomorrow in the morning but i
have also to spend some time with my YL. I hope that can be
arranged...
On the hill i have no internet but i will at least inform
Markus/DF6NM to give those who are interested a information
here...
I have to go now, and will inform you...
73, Stefan/DK7FC
________________________________
Von: [email protected]
<mailto:[email protected]> im Auftrag von
Alexander S. Yurkov
Gesendet: Sa 27.02.2010 20:37
An: [email protected]
<mailto:[email protected]>
Betreff: RE: LF: Fwd: Special Permits for Amateur Radio
Operation below 9kHz?
> when back in the mid 90's the initial request for a longwave
amateur
> segment (what later turned out to be 137kHz) was discussed,
one of the
> big telecom "bobo's" stated that they saw no harm that
amateurs would
> transmit there with max. 1 W EIRP as with that power one
wouldn't be
> able to get any further than the other end of the town.
> It turned out a bit different, unless you see the world as
one big town ;-)
Rik, after some theoretical estimations done i am absolutely
shure
QRSS communications at few 100s km (may be more) is posible on
9 kHz.
There is lot of problems on TX side but them to be solvable.
Main problem
is high voltage on the TX ANT. I expect 100 - 200 kV is
reachable with
some 'tricks' wellknown for power ingeneers. For example one
should avoid
free end of a wire with such a voltage. On should use
'protecting rings'
on the ends. With voltage abt 100 kV seems to be posible use
not too high
antenna. Seems 20-30 m high well top loaded marconi designed
specially for
high voltage is adequate. Remember effective height of 60m
kite antenna
used in DK8KW experiment was 30m (if wire was absolutelly
vertical, does
it was?). With not too high voltage and not too large ANT
capacity 4.5 km
was reached. Another key problem is noise level on this freq.
Now we see
huge discrepancy on the noise level got from different
sourses. What is
the real noise level is not obvious now. Can it be much lower
time to
time? Experements to be usefull. Look at DK8KW web side where
4.5 km
experiment is described. Waterfall background is too smooth. Where
spherics are? This is why i expect RX sensetivity was not as
high as posible. One should remember 4.5 km is begining of the
wave zone
on 9 kHz. At distanses more then 4.5 km field decreases not
too fast with
distance. Another critical distance is abt 100 km where
'waveguide'
propagation starts. At such distances one shold increase TX
ANT voltage
only in 3 times to reach distance 10 times more. Anyway Stefan's
experiment will be very intesesting. And i hope it will be not
the last
experiment.
Regards,
Alexander/RA9MB
