Re: LF: Re: EbNaut considerations for tomorrow...

[DK7FC <selberdenken@posteo.de>]

Hi Luis,

Am 07.06.2019 08:34, schrieb VIGILANT Luis Fernández:

I have the overnight spectrogram at 1min per pixel. The gap on the left at about 21h is the test without antenna

https://www.dropbox.com/s/ojhdcjskefomda2/Benidorm%2090m%20vertical%20LF%20tuned%20VLF%2024KHz%201min%20x%20bin.JPG?dl=0

The elevators QRM is clearly identified and drops from about 00utc to 05utc. Best, lower noise from 03 to 05utc

Someone came home late at night! :-)

Anyway amazingly quite, considering this is urban enviroment and the building tower holds 78 neighbours with all kind

of noisy sources at each home. And a couple of 3 phase 380V variators for the lifts just a few meters under the antenna

Hmmmmm, something is still missing. The QRN usually drops below 4 kHz, like seen on the upper image of my grabber
http://www.iup.uni-heidelberg.de/schaefer_vlf/DK7FC_VLF_Grabber2.html
Now in summer at daylight, that difference (e.g. 8 kHz vs. 3 kHz) can reach > 20 dB, easily.

I still don't see that signal drop on your image, so something is not running optimal. Let's see what happens when you put the transformer on the roof. I think the signal levels will rise at least by 10 dB and hopefully the QRM will not.

73, Stefan

PS: Maybe use a relay to switch the coax cable between LF TX and VLF RX?

73 de Luis

EA5DOM