27 Nov 2017

17kHz VLF tests (amateur)

Stefan DK7FC who is well known for his sub-9kHz tests recently applied for special permission to test around 17kHz with a low ERP.

"Hi VLF,

Since 23 UTC a 700 mA carrier is running on 17.4701 kHz!
It is a little surprise to the VLF community i think ;-)

Legal? Yes: http://www.iup.uni-heidelberg.de/schaefer_vlf/VLF/17,47kHz_Sonderlizenz.jpg
Actually the document has 3 pages but the other ones are no so relevant.
My ERP is limited to 5 mW. I did not request more because more isn't possible anyway with this antenna.

I wound a big single layer coil with 0.5 mm enameled wire on a PVC tube with 315 mm outher diameter.
0.7 A is just a first careful step. The coil is designed to hold 1.5 A 'key down'.
The carrier will run the whole night and even tomorrow at daytime.

Worldwide reports are welcome ;-)
It is not sub-9-kHz but still VLF, the 17 km band!! So give it chance :-)

The tree has still some solar power to stream the signal from the EW loop down to the city, so there is a feedback spectrogram at http://www.iup.uni-heidelberg.de/schaefer_vlf/DK7FC_VLF_Grabber2.html

73, Stefan

PS: I still can hear that tone of the coil. It is terrible! Be happy when you are older than me!"

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