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i.
Rotate the VO LTS/DIV VAR control to the clock
wise position.
j.
Check that the display is less than 33% o f the
calibrated display. Return VO LTS/DIV VAR to the CAL
detent.
15. Check/Adjust Vertical Step Response
a. Set the VO LTS/DIV switch to .1.
b. Set the SEC/DIV switch to 1 p.
c. Connect the fast-rise, positive output of the square-
wave generator to the 221. Use a GR to BNC adapter, a
50-ohm termination and a probe tip to BNC adapter.
d. Set the square-wave generator to 500 kHz. Adjust the
sqaure-wave generator output fo r a 5-division display.
e. Set the HORIZ-MAG to 10X.
f. Position the positive-going signal in the center of the
graticule, with the top of the square wave visible.
g. Adjust C432 (Bandwidth response) fo r the fastest rise
time. See Fig. 5-7.
h. Check aberrations fo r less than +5%, —5%, 5% peak
to peak.
i. Adjust C l67 for a fla t top with minimum aberrations
(a slight readjustment o f the C432 might be necessary fo r a
fla t top w ith no overshoot). See Fig. 5-6 and Fig. 5-7.
Fig. 5-7. Location of Bandwidth response adjustment.
REV. B, FEB. 1976
16. Check/Adjust Vertical Bandwidth
a.
Set the VO LTS/DIV switch to .1, the SEC/DIV
switch to 1 m and MAG to IX .
b.
Connect the constant amplitude signal generator to
the 221. Use a GR to BNC adapter, 50-ohm termination
and a probe tip to BNC adapter.
c. Set the constant amplitude signal generator to
50 kHz, and adjust the output amplitude o f the constant
amplitude signal generator for a deflection of six divisions.
d. Adjust the frequency of the constant amplitude
signal generator until 4.2 divisions o f deflection are present
on the crt screen.
e.
Check that the frequency of the constant amplitude
signal generator is greater than 5 MHz.
f.
Adjust C432 fo r a deflection of at least 4.2 divisions
at 5 MHz. Check display for a clean step response. See step
15.
17. Check Vertical Position Range
a. Connect the constant amplitude signal generator to
the 221 oscilloscope. Use a GR to BNC adapter and probe
tip to BNC adapter.
b. Set the VO LTS/DIV switch to .1.
c.
Set the constant amplitude signal generator to 50kHz
reference, and adjust amplitude controls for a four-division
display.
d. Set the VO LTS/DIV to 20 m.
e. Check that the bottom
positioned above the graticule center line and that the top
of the display can be positioned below the graticule center
line.
18. Check Input Noise
a. Set the INPUT COUPLING switch to GND.
b. Set the VO LTS/DIV switch to 5 m.
Calibration—221 Service
o f the display can be
5-9
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