pictures

All modules connected

This pictures shows the spectrum from 1 to 100 MHz


I found out why the shown signal strengths are dependent on the center frequency.
The problem is that the sweep speed is too high. The faster the sweep the lower the amplitude. The sweep speed is not constant so the amplitude of the measured signals changes. For low sweep speeds the problem does not occur. I can use 2 MHz/div using a sweep frequency of 32Hz. So I have to decrease the sweep frequency. I will use 1 Hz. as sweep frequency.