Figure 1 – The Murata UWE-24/3-Q12 DC-DC converter. The manufacturer recommends specific capacitors on the input and output and I’ve tack-soldered these on as shown.
Figure 2 – The test setup for evaluating the conducted emissions from the Murata DC-DC converter.
Figure 4 – The results with the 100 uH inductor installed (blue trace) looking from 150 kHz to 150 MHz. The red trace is the unfiltered noise and the yellow trace was the ambient baseline noise. The display line is the approximate emissions limit.