Calibration Procedures 3
Keysight E3633A and E3634A Service Guide 63
CV PARD (ripple and noise)
Periodic and random deviations (PARD) in the output (ripple and noise) combine
to produce a residual ac voltage superimposed on the dc output voltage. CV
PARD is specified as the rms or peak-to-peak output voltage in the frequency
range from 20 Hz to 20 Mhz.
VRMS measurement techniques
When measuring Vrms ripple and noise, the monitoring device should be plugged
into the front of the terminals at (B) in Figure 3-2. Use the coaxial cable and BNC
female to banana plug adapter to connect the monitor device to the power
supply. To reduce the measurement error caused by common mode noise, it is
recommended that you use a common mode choke between the cable and the
BNC adapter. The common mode choke is constructed by inserting coaxial cable
into Ferrite Toroidal core. The load resistor should be connected to the terminal at
(A) in Figure 3-2. Twisted leads between the load resistor and the power supply
helps reduce noise pickup for these measurements.
1 Turn off the power supply and connect the output to be tested as shown in
Figure 3-1 to an oscilloscope (ac coupled) between (+) and (-) terminals. Set
the oscilloscope to AC mode and bandwidth limit to 20 MHz. Connect a
resistive load (2.0
Ω
)
[1]
or (12.5
Ω
)
[2]
to the terminal at (A) in Figure 3-2.
2 Turn on the power supply. Select the 20V/10A
[1]
or 50V/4A
[2]
range, enable
the output, and set the display to the limit mode. When the display is in the
limit mode, program the current to the full rated value (10.0 A)
[1]
or (4.0 A)
[2]
and the voltage to the full rated value (20.0 V)
[1]
or (50.0 V)
[2]
.
3 Check that the front panel CV annunciator remains lit. If not lit, adjust the load
down slightly.
4 Note that the waveform on the oscilloscope does not exceed the peak-to-peak
limit of 3 mV.
5 Disconnect the oscilloscope and connect the ac rms voltmeter in its place
according to the VRMS measurement techniques above. The rms voltage
reading does not exceed the rms limit of 0.35 mV
[1]
or 0.5 mV
[2]
.
[1] For Keysight E3633A Model
[2] For Keysight E3634A Model
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