Tektronix 7B92 Instruction Manual page 43

Calibration-7B92 Service
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Fig. 4-5. Typical CRT display when adjusting high-frequency
linearity (C557, C565, C572).
28. Check/Adjust High-Frequency Timing (R244,
R246, R567)
a. Install the 7A19 Amplifier directly into the Left Vert
compartment of the 7904 Oscilloscope and 7B92 Time
Base directly into the B Horiz compartment.
b. Connect the output of the time-mark generator to
the 7A19 Input with a 42-inch 50-ohm BNC cable. Set the
time-mark generator for 2 ns markers.
c. Change the following control settings:
Vertical Mode
Horizontal Mode
Main Triggering
SOURCE
LEVEL
TIME/DIV OR
DLYTIME
7904 Oscilloscope
Left Vert
B
7B92 Time Base
INT
Adjust for stable
display
.1 /1S
DL Y'D Time/Division
.5 ns (press in for DL Y'D
Sweep Display Mode)
d. Adjust the 7 A 19 Volts/Division switch for about two
divisions of display. Adjust the 7B92 and oscilloscope
Intensity controls as necessary. Center the display on the
CRT with the 7 A 19 and 7B92 POSITION controls.
NOTE
Timing checks must be made with the 7892 installed
directly into the oscilloscope. Adjustment of R567
4-22
Scans
bv
OutsouTce-Options
=>
can be made by reaching into the center two
compartments of the oscilloscope (be certain that the
7 A 19 side covers are on). R244 and R246 can be
adjusted through the top plug-in housing or by
removing the 7892 from the oscilloscope.
e. CHECK-CRT display for two complete cycles over
the center eight graticule divisions.
f. ADJUST -R567, .5 ns Timing, for two complete
cycles over the center eight graticule divisions.
g. Change the D L Y'D Time/Division switch to 1 ns.
h. CHECK-CRT display for one complete cycle in two
graticule divisions.
i. ADJUST -R246, 1 ns Timing, for one complete cycle
in two graticule divisions.
j. Change the D L Y'D Time/Division switch to 2 ns.
k. CHECK-CRT display for one complete cycle each
division over the center eight divisions of the graticule.
I. ADJUST -R244 for one complete cycle each division
over the center eight divisions of the graticule.
NOTE
If
R244, R246, or R567 cannot be adjusted to the
given tolerances, repeat calibration step 27_
Y29.
Check Delaying and Delayed Sweep Timing
Accuracy
NOTE
The tolerance in steps
29
and 30 are for an ambient
temperature range of +1!JC to +35°C. If outside this
range, see Specifications in the 7892 Operator's
Manual for applicable tolerances.
a. Change the following control settings:
ALT
DELAY TIME MULT
OUT (TRACE SEP
fully clockwise)
0.00
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