Performance Check Procedure
6. A and B M agnified Tim ing Accuracy and Linearity
a. Set time-mark generator for 20 ns time marks.
b. Set:
Horizontal MODE
A SEC/DIV
Horizontal MODE
B SEC/DIV
XI0 MAG
CH 1 VOLTS/DIV
A
20 ns
B
20 ns
On (for 2 ns/div sweep speed)
0.5V (use 0.2 V for the 5 ns
time markers If necessary)
c. Set the Horizontal POSITION control to 12 o’clock, and then align the
rising edge of the nearest time marker to the second vertical graticule
line (center the display vertical).
NOTE
For the fastest sweep speeds, where the time marker peaks are
rounded and not well defined, greater resolution can be achieved
by vertically centering the display and using the point where the
rising edge of the time marks cross the center horizontal
graticule line as a reference.
d. CHECK—that the rising edge of the fourth displayed time marker
crosses the center horizontal graticule line at between 8.27 divisions
and 8.73 division from the left-most graticule line.
e. CHECK—that the spacing of the time markers over any 2.5 division
interval within the center eight divisions does not deviate from the value
measured at the center 2.5 divisions by more than 0.12 division. Use
the fifth vertical graticule line as a starting point for the measurement
at the center 2.5 divisions. Exclude the first 1/4 division or 25 ns and
any portion of the sweep past the 100th magnified division.
f. Set SEC/DIV to 5 ns.
g. Set the Horizontal POSITION control to 12 o’clock, and then align the
nearest time marker to the second vertical graticule line.
h. CHECK—that the tenth displayed time marker is within 0.24 division
(left or right) of the tenth graticule line.
j. Repeat the timing and linearity checks for all SEC/DIV settings between
10 ns and 0.5 ms. Use the SEC/DV and Time Mark Generator X10
MAG settings given in Table 7-3.
2245A Operators 7-41
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