Hello Markus, VLF,
Am 21.06.2011 00:00, schrieb Markus Vester:
Total resistance of the antenna
circuit was around 280 ohms (including 140 ohms for the coil). This is
about half of that when I used the same kite antenna in Bamberg with
only a few short ground pegs.
Excellent! I wish to have such a low earth resistance. Also 140 Ohms
for the coil is very good. Mine has 185 Ohm for 190 mH but therefore no
HV problems so far, even at 1.7 A antenna current (in the 10th exp
during the CW transmissions)
BTW all seven buckets connected to
900 pF resonate at about 4.6 kHz - Stefan, how about a 65 km band ;-)
65 km sounds good! ;-) Would be the lowest frequency ever. You should
be the first one to transmit there. If you early announce such a test i
would run a "DFCW-2400" window on 4600 Hz.
But as we planned, we should think about coupling our coils in a common
meeting, maybe on my 12th experiment. You seem to have 1.3 H. Coupling
with my 550 mH coil may achieve 2 H. If we would use my 300m vertical
which has about 1650 pF we could transmit on 2.77 kHz, ULF, the 108 km
band! :-) What do you think? We could generate about 7 mW ERP!
On my own grabber, I attempted
to compare signal levels from DK7FC (-71 dB, 180 km) and myself (-43
dB, 4.5 km). Correcting this difference (28 dB) by the EMRP ratio (26
mW / 1.2 mW = 13 dB), distance ratio (1/r = 32 dB) plus an
additional nearfield correction (1/r³ instead of 1/r from 4.5 to 5.3
km = 3 dB), we find that Stefan was 28+13-35
dB = 6 dB weaker than we would expect by pure groundwave. This
corresponds very well to the earlier experience that there is a midday
skywave cancellation effect for about 200 km.
Interesting!
73, Stefan/DK7FC
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