Checks and Adjustments
Timing
Check
The period of the CALIBRATOR signal automatically tracks the A SEC/DIV
setting within the range of 100 ms to 100
AJS.
Within that SEC/DIV range, the
CALIBRATOR period is 200 ms to 200 ns, 5 cycles per 10 divisions of the
A Sweep. To quickly check the operation and calibration of the oscilloscope timing,
use the following procedure:
NOTE
Auto Setup and Parametric Measurements will not work using the Calibrator
signal.
1.
Obtain a display as described in "Initial Setup."
2.
CHECK—Timing accuracy by confirming that five complete cycles of the
square-wave signal are displayed over 10 major divisions (±0.1 division)
along the center horizontal graticule line for all A SEC/DIV settings from
100 ms to 100 ns. Confirm that 2 cycles of the Calibrator signal cover
8 divisions at 50 ns/div and that 1 cycle covers 10 divisions at 20 ns/div.
Observe that the displayed transition time of the signal remains
approximately the same when A SEC/DIV is changed to 10 ns and 5 ns.
(The number of horizontal divisions covered by the transition time at 10 ns
per division should be two times the number covered at 20 ns, and the
number of divisions at 5 ns should be four times the number at 20 ns.)
Return A SEC/DIV to 1 ms, switch the X10 MAG on, and CHECK—that
1/2 cycle covers 9.8 to 10.2 divisions.
3. Set X10 MAG Off and carefully align the it cursors with the falling edges of
the first and fifth cycles. CHECK—At reading is within 7.93 ms to 8.07 ms.
Repeat the test at any A-Sweep speed in the 100 ms to 100 ns range.
4.
If desired, delay timing can be checked by using Alt horizontal display
mode,
RUN AFT DLY B-Trigger mode, and At. Set the A REF AND DLY
POS and A controls to align the intensified zones with the falling edges of
the first and fifth cycles and superimpose the expanded display of the
edges on the B Sweep, running at least 10 times faster than the A Sweep.
CHECK—At reading is 8 times the A SEC/DIV setting, ±0.5%.
2465B/2455B/2445B Operators
4-7
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