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bated
Zero level, positive pulse
Change the previous settings of the pulse generator as follows:
AMPLITUDE IN 50 Q, S4
+3V
Vernier, RV5
MAX.
-
NORM. INV., S8
NORM.
Set the TIME/cm switch of the oscilloscope to 1 us/cm.
Requirement:
When turning vernier RV5 from one extreme position to the other, the base line of
the pulse may not shift more than t 25 mV symmetrically around the zero level.
— Turn RVS.
— Coarsely adjust the deviation amplitude with RV302 (do not care about the
symmetry yet).
— Set the oscilloscope input sentitivity to 5 mV/cm and check the adjustment by
turning vernier RV5. Readjust if required.
— Remove the signal from the oscilloscope and note the position of the zero level.
Reconnect the signal.
— If required, adjust RV303 so that the base line of the pulse coincides approximate-
ly with the zero level.
— Centre the zero line.
— Turn vernier RVS again and check the symmetry of the base line shift.
Readjust, if necessary, with RV303.
~ Alternate between RV302 and RV303 until a base-line shift of + 25 mV
symmetrically around the zero level is obtained.
— Finally, repeat the procedure from point C.1.
. Pulse shape adjustment
Set the pulse generator and oscilloscope as detailed in point C except the following:
Pulse generator
REPETITION TIME
1 ps
DELAY
5 ns
WIDTH
5 ns
WIDTH FINE
fully clockwise
NORM./INV.
NORM.
Oscilloscope
TIME/cm
5 ns
-- If an overshoot or rounding is visible on the leading edge of the pulse, adjust
RV306 until the overshoot or rounding has vanished. See Fig. X-5.
— Switch to the INVERTED mode and check that no rounding has occured on
the trailing edge.
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