Teledyne LeCroy DA1855A - Manual (Page 33)

Operator’s Manual
922258-00 Rev A 27
Comparison Voltage Operation (V
COMP
)
Set the DA1855A as follows:
PVG Mode OFF
+Coupling DC
–Coupling Grounded (OFF)
DA1855A (Atten/Gain) Manual
List Select: Upper BWL FULL BWL
List Select: Gain X10
List Select: Atten ÷1
List Select: Inpur R 1 M Ω
Set the Function generator’s output to 50 kHz and 100 mVp-p sine wave and the output connected
to the DA1855’s +INPUT.
Set the oscilloscope to 5 mV/div. Under these conditions, the display on the oscilloscope will extend
off the top and bottom of the screen.
In the PVG Mode menu switch to V
COMP
. This internally applies the Precision Voltage Generator’s
output to the –INPUT. The OFF light on the DA1855A’s front panel goes out and the –Coupling menu
on the user interface disappears (the –INPUT connector is disabled).
The positive and negative peaks of the waveform displayed on the oscilloscope are (respectively) 10
divisions above and below the display center line. Rotate the OFFSET knob on the oscilloscope until
the positive peak of the waveform appears in the oscilloscope’s display. Continue adjusting the
OFFSET knob until the peak of the waveform is at the centerline of the oscilloscope’s display. The
number in the Precision Voltage Generator display is the waveform’s positive peak voltage.
Rotate the OFFSET knob clockwise until the negative peak of the signal is now at or near the
oscilloscope’s display centerline. By adjusting the OFFSET knob, the negative peak can be positioned
to the oscilloscope’s display centerline. Now the number in the Precision Voltage Generator’s
display is the waveform’s negative peak voltage.
Change the oscilloscope’s sensitivity from 5 mV/div to 1 mV/div. Select Auto Zero in the List Select
menu and push the button next to Auto Zero window to cause the DA1855A to adjust its DC
balance.
Change the OFFSET control to again place the negative peak of the waveform at the oscilloscope’s
center screen. Note that the Precision Voltage Generator’s display represents the negative peak
voltage of the waveform with greater resolution.
Return the oscilloscope’s sensitivity to 50 mV/div and select OFF or in the PVG Menu. The Precision
Voltage Generator will retain its setting and the display on the oscilloscope will be centered about