User Manual

Adjustment Proc
edures
2. Set the probe to ÷ 5 attenuation, 5 MHz bandwidth, DC reject off.
3. Se t the function generator to square wave, 1 ms period (1 kHz frequency), approximately 4 V pk-pk, (2 Vpk).
4. Set the oscilloscope to display channel 1. Set channel 1 to DC and 50 Ω input impedance (or use external terminator), 2
mV/div. Set the time/division to 10 s/div. Set the trigger source to external (or Channel 2) Set the acquisition mode to
average 8 to 10 acquisitions. Apply vertical bandwidth limiting if available to reduce noise.
5. Ad just the trigger level for a stable trigger. (If the trigger is obtained through channel 2, it may be necessary to change
the volts/div setting.)
6. The displayed square wave is the common mode feedthrough. If the probe is severely misadjusted the waveform may be
off screen. If necessary, increase the channel 1 volts/div to keep the waveform on screen.
7. Ad just the ÷ 5 DC CMRR adjustment for minimum amplitude in the flat portions of the displayed waveform. This
adjustment does not effect the leading edge transitions. Increase the vertical sensitivity a s the amplitude decreases.
8. Change the probe to ÷ 50 attenuation.
9. Se t the function generator to square wave, 1 ms period (1 kHz frequency, approximately 10 Vpk-pk, (5 V peak).
10. A djust the ÷ 50 DC CMRR adjustment for minimum amplitude in the flat portions of the displayed waveform. This
adjustment does not effect the leading edge transitions.
11. Keep the connections for the next procedure.
P6250 & P6251 Technical Reference 47