Hi Wolf and tnx for informing others,
After a talk with Markus/DF6NM and further thoughts abt the actual
configuration it may be difficult to get a success tomorrow:
The coil has a Q of just 38 (that i have measured/calculated). So it has an
"internal" R of abt 150 Ohm @ 8,9kHz. With that coil it will not be possible to
get 20kV (abt 650mA into the wire) on the wire unless my PA won't give 2kW and
it won't. So the ERP will be lower.
Also, it is not sure if Bernd/DF8ZR (closest distance RX stn as it seems) can
arrange his equipment until tmw.
Anyway, i will get up tomorrow early in the morning and try to built that PA.
Additionally i try to build quickly an antenna current meter with a high µ
ferrit core (current transformer). So, the current and ERP and earth losses
could be calculated. Maybe a confirmation of that what we have discussed in the
last days (changes of earth resistance from 137 to 9 kHz...).
First i will just do some resonating tests. Bringing the wire to resonance,
matching it to the PA. Trying to get the power coupled into the HV coil.
It will be a first step to built up that station, although it might be possible
that it won't come up completely, there will be some results that shows what to
do next and to improve.
I have built such an earth loss measuring bridge before some years (if i
remember correctly it is from EI0CF/G3YNK) and will try to find the R and C for
9kHz with this antenna, although the ferrite cores might be not optimal at
those low frequencies.
Markus/DF6NM will be on the phone and i will inform him when i am ready to
transmit. He gave me the hint that it is an idea not to transmit exactly at 8,9
but thater at 8,97kHz, due to the harmonics of 50Hz and 16 2/3 Hz (german
railway f), although these may be not to strong any more. He will spot the QRG
and if i am transmitting here. Now i plan it on 8,9700kHz.
Maybe there will be no reception from anyone on my first test since there seems
to be no one QRV in a radius of 10...20km but if i know the earth losses and
the actual voltage at the wire at a given power (measured, not theoretically
calculated) i will be happy. But maybe it will be much better than just
thought...
Until next week, i try to get a proper coil in the region of 0,5H, so that no
parallel C will be needed...
Ok, so, cu there...
73 es gn es gl, Stefan/DK7FC
________________________________
Von: [email protected] im Auftrag von Wolfgang Büscher
Gesendet: Sa 27.02.2010 15:41
An: [email protected]
Betreff: Re: AW: LF: Re: 9kHz noise level
Hi Stefan,
Thanks for the proposals, and the boost of activity. I have passed on a
few notes to the yahoo VLF group, so if you have more details about the
kite antenna experiments (or even a schedule) please let us know.
RX equipment (SDR-IQ and Perseus, plus various active antennas) already
geared up here; and even the 'quiet RX location' (DF0WD / DK4U) is
accessable by car again, since the snow disappeared. It may be a bit
optimistic to expect reception here in JO42FD, but who knows...
Cheers,
Wolf .
Stefan Schäfer schrieb:
> Dear group,
>
> It seems that there are interesting theoretical questions to answer. And we,
> the practical interested's, could do this by trying that. Anyway if it is
> over 10km or 200km... Maybe we'll get some nice surprises...
>
> Stefan/DK7FC
>
>
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