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Date: Sun, 28 Feb 2010 16:32:10 +0000
From: tim hague <m0afj@dsl.pipex.com>
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To: rsgb_lf_group@blacksheep.org
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Subject: Re: LF: Re: Re: VLF TX experiments this sunday
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mal hamilton wrote:
> Pse qsp to Stefan to SHOUT from his hill top and face DOWN wind for an=
=20
> extra 23 dB. If all 9 DREAMERS face his direction records could be=20
> broken without the KITE,
> Do not break WIND to avoid QRM during the listening period.
> =20
> G3KEV
> =20
>
>     ----- Original Message -----
>     *From:* Markus Vester <mailto:markusvester@aol.com>
>     *To:* rsgb_lf_group@blacksheep.org
>     <mailto:rsgb_lf_group@blacksheep.org>
>     *Sent:* Sunday, February 28, 2010 12:48 PM
>     *Subject:* LF: Re: VLF TX experiments this sunday
>
>     Dear LF,
>     =20
>     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.
>     =20
>     Kind regards,
>     Markus (DF6NM)
>     =20
>
>         ----- Original Message -----
>         *From:* Stefan Sch=E4fer <mailto:schaefer@hst.tu-darmstadt.de>
>         *To:* rsgb_lf_group@blacksheep.org
>         <mailto:rsgb_lf_group@blacksheep.org>
>         *Sent:* Saturday, February 27, 2010 3:33 PM
>         *Subject:* LF: VLF TX experiments this sunday becomes more
>         probably
>
>         Dear LF group,
>         =20
>         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.
>         =20
>         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 ;-=
)
>         =20
>         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;-)
>         =20
>         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...
>         =20
>         On the hill i have no internet but i will at least inform
>         Markus/DF6NM to give those who are interested a information
>         here...
>         =20
>         I have to go now, and will inform you...
>         =20
>         73, Stefan/DK7FC
>
>         ________________________________
>
>         Von: owner-rsgb_lf_group@blacksheep.org
>         <mailto:owner-rsgb_lf_group@blacksheep.org> im Auftrag von
>         Alexander S. Yurkov
>         Gesendet: Sa 27.02.2010 20:37
>         An: rsgb_lf_group@blacksheep.org
>         <mailto:rsgb_lf_group@blacksheep.org>
>         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. Whe=
re
>         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
>
>
>
>
Why is there such derision about experimentation?, I for one am looking=20
forward to the results of these tests. I am sure that comments like this=
=20
from the UK do nothing to enhance our reputation among the greater=20
amateur community.

Tim M0AFJ