Appendix Service Information
Constant Current (CC) Verifications
177
Service
Information
CC PARD (Ripple and Noise)
Periodic and random deviations (PARD) in the output (ripple and noise)
combine to produce a residual ac current, as well, as an ac voltage
superimposed on the dc output. CC PARD is specified as the rms output current
in a frequency range 20 Hz to 20 MHz with the power supply in constant current
operation.
1 Turn off the power supply and connect the output to be tested as shown above
with the current monitoring resistor 0.2
9 (R
M2
) across output terminals.
Connect a rms voltmeter across the current monitoring resistor as shown
above.
2 Turn on the power supply. Select the low voltage range (8V/3A)
†
, enable the
output, and set the display to the limit mode. When the display is in the limit
mode, program the current to full scale rated value (3 A)
†
and the voltage to
the full scale rated value (8.0 V)
†
.
3 Divide the reading on the rms voltmeter by the load resistance to obtain rms
current. The readings should be within the limit of 4 mA.
Note: For better measurement result, it is recommended to make the connection between
the BNC receptacle and the output terminals shorter as much as possible, and to use
the recommended split ferrites with the cable (BNC to BNC) as shown above.
Input
RMS voltmeter
Input
RMS voltmeter
(Front Panel Connections)
(Rear Panel Connections)
Current
Monitoring
Resistor
Current
Monitoring
Resistor
BNC Cable
BNC
Receptacle
Split
Ferrites
†
For E3640A model, and see Table A-3
for other models
