DER-46
6 W peak, Multiple output PSU for DVB-T
April 20, 2005
11.2 Output Ripple Measurements
11.2.1 Ripple Measurement Technique
For DC output ripple measurements, a modified oscilloscope test probe must be utilized in
order to reduce spurious signals due to pickup. Details of the probe modification are provided
in Figure 8 and Figure 9.
The 5125BA probe adapter is affixed with two capacitors tied in parallel across the probe tip.
The capacitors include one (1) 0.1 µF/50 V ceramic type and one (1) 1.0 µF/50 V aluminum
electrolytic. The aluminum electrolytic type capacitor is polarized, so proper polarity
across DC outputs must be maintained (see below).
Probe Ground
Probe Tip
Figure 8 - Oscilloscope Probe Prepared for Ripple Measurement. (End Cap and Ground Lead Removed)
Figure 9 - Oscilloscope Probe with Probe Master 5125BA BNC Adapter. (Modified with wires for probe ground
for ripple measurement, and two parallel decoupling capacitors added)
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