Hi Stefan …. SLF :-O
There is film actually in Cinema: “First Man”
Is that about you ?? ;-)
Congratulations
PS: Back from trip. Will try to catch you all in LF activity if storms finally finish here
73 de Luis
EA5DOM
Hi SLF,
Attached is a spectrogram from a reprocessing of my recent DFCW-5400 transmission down on 270 Hz. The SNR reaches up to 30 dB in that bandwidth. It shows that messages could be exchanged up to 10 km distance if there would be someone with a suitable RX/TX system.
Now after 'saying hello' on that 1110 km band, i'll continue my trip to the end of the spectrum. Next station is near 80 Hz, TXing deeper than ZEVS. Maybe i'll come back to 270 Hz from the ground loop antenna, if the coming experiments on 470 Hz will be successful.
73, Stefan
Am 06.11.2018 14:55, schrieb DK7FC:
SLF,
Now, a 30 character EbNaut message has been sent over the short path. Reception was excellent, with several dB over the decode limit. Even with that pW power range, some distance can be crossed. With the ham density in my region, it should be possible to reach
someone else (theoretically!) who can copy the message and attempt for a split-band two way contact.
Capture attached.
73, Stefan
Am 05.11.2018 23:14, schrieb DK7FC:
Well, today, i did a first step into the ITU radio band 2,
SLF.
Since 21:00 UTC i'm transmitting on the INV-L on 270.01 Hz. The antenna current is just 2.5 mA. The ERP is about 6 pW.
Almost nothing but anyway a trace becomes visible now on my RX on the tree in 3.5 km distance (http://www.iup.uni-heidelberg.de/schaefer_vlf/DK7FC_VLF_Grabber2.html)
Of course this is a near field experiment. There, on the 1110 km band, the far field begins at a distance of 177 km.
On the transmitter site i'm using the modified 5 kV mains transformer that was used to produce 5 kV at 970 Hz. Now there is a series capacitor of about 20 uF applied to the primary winding. Together with internal reactances this maximises the peak of the fundamental
frequency of the output voltage.
The goal of this first experiment is just to put the foot into this part of the radio spectrum. And to do some pre-tests, trying to optimise filter and blanker settings for future tests.
In the end i'm planning to work on that frequency from the ground loop antenna, which is still in the near field, but anyway :-)
73, Stefan
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