5
Service Guide
66
Keysight U8001A/U8002A User’s and Service Guide
CV noise
CV noise is specified as the RMS or peak-to-peak output voltage in the frequency
range from 20 Hz to 20 MHz.
Procedures:
1
Power off the power supply and connect the output to be tested as shown in
to a differential amplifier and load resistor (10
Ω
for U8001A and
6
Ω
for U8002A)
2
Power on the power supply.
3
When the display is in the limit mode, program the output voltage to full rated
value, i.e. 30 V and output current to the maximum programmable value.
4
Enable the output of the power supply.
5
Make sure that the power supply is in CV mode. If not, adjust the resistive load
so that the output current drops slightly until the power supply is in CV mode.
6
Configure the differential amplifier as follow:
– Set to AC mode (positive and negative) to removes the DC component
– Set to differential mode
– Set gain to x10
– Set attenuation to 1
– Set low pass filter to 20 MHz bandwidth limit to filter out input signal which
contains higher frequency
– Set to zero precision voltage generator
– Set input impedance to 1 M
Ω
7
Configure the scope as follow:
– Set time range to 50 ms (20 Hz)
– Acquires every single sample at the maximum sampling rate and retains
only the min and max values in a “sampling region” (50 ms time range)
– Enable 20 MHz cut off frequency for better high frequency cut-off
– AC coupling
– Enable Auto-triggering
8
Allow the scope run for a few seconds to generate enough measurement
points.