Hello again, i finally got some time yesterday to install and use a spectrum analyzer.
I used a RTL-SDR v2 (metal case) with the supplied antenna. In my first test, i placed the antenna next to the Outernet Receiver.
You can see that there is a signal from the pc between 1,6ghz and 1,62ghz.
I the placed the Antenna on my Desk (1m from the pc that stands on the desk) in my second Test.
I also tested if the interferance gets stronger if my GPU is at full load. You can see that there is more noise from 1,3ghz to 1,5ghz, but the signal mentioned before doesen't get stronger.
I also shielded the antenna with a thin carbon sheet that reduced the signal loss. I will test some more shieling soon.
The ferrites also arrived yesterday, but the don't seem to effect the signal when clamped around the USB cables and Antenna cable.