Hello Tom,
Thanks for the hint. No i did not yet see the trace on Paul's grabber. I
had to spend some time with the YL. But now i have some time for
charging the batteries and doing some postprocessing.
Amazing, this antenna seems to perform much better than we expected!
Maybe Paul also picked up something on 5170 Hz? If the trace on Pauls
grabber is actually mine, it is a new big step for TX earth antennas.
Well, as mentioned in my first email there are 3 such guide rails. The
street is going slightly upwards and in this experiment i have connected
the wire to the lower and the middle guide rail. I already measured the
upper guide rail. It is much longer than the other ones, maybe 200m.
There are about 40 massive poles holding the rail. All of the rail
segments have contact to the neighbour rail but only about 20 poles have
contact to the rails. Anyway this is very good but there is some room
for further improvements in future steps.
For tomorrow i'm planning another experiment starting earlier, maybe 8
UTC or so (lower QRN). I will use the upper and the lower rail so the
wire length will be about 900 m! Then, will the area of the loop be 2
times higher or 4 times higher, or even more?
I'm now going to prepare some spectrum plots and spectrogram,
postprocessing of the recorded audio data from today.
73, Stefan
Am 28.07.2018 17:18, schrieb DK1IS:
Hi Stefan,
congrats for that ufb earth antenna experience! You have certainly
seen it already: from 9 to 10 UTC there was a clear trace from the
east at Paul´s grabber:
http://78.46.38.217/fbins3.html#p=1532782800&b=110&s=sp&m=cardioid&w=r&h=62&z1=0.34&z2=0.64&c=1
- it should have been your signal! But sorry: at a first glance no
signal at the DL0AO grabber but we have a lot of heavy QRN here today.
73 es gl,
Tom, DK1IS
Am 28.07.2018 um 11:43 schrieb DK7FC:
Hi VLF,
I'm sitting in my car while writing this email. I'm in JN39WI96GX and
i transmit on 8270.000 Hz with a GPS locked signal generator into an
about 450 m long earth antenna using two guide rails as the earth
electrodes on both ends. On each end there are 16 (18) massive T-T
poles holding the guide rail, providing a super good earth coupling.
I measured that they are connected to each other.
The transmitter is on the air since 9:08 UTC running 550 mA with just
75 W DC inout power into my hand warm lossy linear mode VLF PA!
I'm amazed about the low losses! At DC i got 447 mA at 50.9 V. The
wire is 0.4 mm diameter so it has 63 Ohm. That means the ground loss
is just 50 Ohm !!!! Amazing! And i have no efforts to build up a
ground connection here, i just need to connect the wire. Since the
wire losses are higher than the ground losses, i can get maybe 2 dB
more signal when buying some better wire. I already found a source
that offers 0.75 mm^2 100 m loudspeaker cable (i.e. 200m wire)for
just 13 EUR....
BTW i even have an ugly old scope here which is battery powered. I
can see that the phase of voltage and current is slightly inductive,
maybe 30 deg or so. So i could series resonate the antenna with some
C. This is for the next experiment...
The signal becomes visible on my grabber now, in 424 uHz and also
some bright pixels in the 3.8 mHz window.
I'm going to stop the carrier at 10:08 UTC, after 1 hour. Then i'll
continue on 5.17 kHz!
BTW the antenna , if it works like a real loop, is beaming directly
to Paul Nicholson ;-)
73, Stefan
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