Tektronix 2A61 Instruction Manual page 22

Performance Check—-Type 2A61
Level Auto
Slope +
Coupling AC Slow
Source Int
1. Adjust Output Amplifier DC Balance (Front
Panel)
Requirement-Correct operation of Amplifier Balance, as
follows:
a. Position the trace to the Type 561A CRT graticule center
with the Type 2A61 POSITION control.
b. Push the Trace Restorer button, concentric with the
POSITION control, on the Type 2A61 while adjusting the DC
BAL control to move the trace to the graticule center.
c. Hold the Trace Restorer button down. Set the Type
2A61 mV/DIV switch to 1 and set the trace to the graticule
center with the POSITION control.
d. Switch the mV/DIV switch fo .02 and adjust the DC
BAL to move the trace to the graticule center.
e. Repeat the above steps until the trace remains centered
while switching the mV/DIV switch between .02 and 1.
f, After the final adjustment the DC BAL contro! should be
at midrange, +90°.
2. Check mV/DIV Switch Positions
Requirement-The display amplitude must be within +5%
of the mV/DIV switch indication.
a, Reset the following controls:
Type 2A61
INPUT SELECTOR A
MILLIVOLTS/DIV 20
b. Connect the 1000:1 Divider, set to 1, to the Standard
Amplitude Calibrator Output.
c. Connect the Special Input Cable (4 pin connector on
one end, BNC connector on the other) to the 1000:1 Divider.
d. Set the Standard Amplitude Calibrator Mode to PL]
and the amplitude to .1 volt.
e, Set the Type 2A61 GAIN ADJUST control for exactly
5 divisions of display on the Type 561A CRT.
f. Check each of the positions of the mV/DIV switch
through .05. Switch the Standard Amplitude Calibrator Ampli-
tude simultaneously, as follows:
TABLE 5-1
mV/DIV Standard Amplitude Divisions
Switch Calibrator, mV of Display
10 50 5, +5%
5
20
4, +5%
2 10 5, ==5%
1 5 5, 5%
5 2 4, £5%
2 1 5, =5%
Jl 5 5, &5%
05 2 4, +5%
g. Switch the 1000:1 Divider to 1000.
h. Switch the Type 2A61 mV/DIV switch to .02.
i. Switch the Standard Amplitude Calibrator Amplitude
to .1 volt.
j. Observe 5 divisions, +5%, of display.
k. Switch the mV/DIV switch to .01.
1. Switch the Standard Amplitude Calibrator Amplitude
to 50 mV.
m. Observe 5 divisions, +5%, of display.
n. Switch the Type 2A61 mV/DIV to 20, the 1000:1 Divider
to
X1 and the Standard
Amplitude
Calibrator to 0.1 V.
3. Check mV/div Variable Ratio
Requirement-Not less than 2.5 to 1.
a. Rotate the mV/DIV VARIABLE control completely coun-
terclockwise.
b. Check for not more than two divisions of display on the
Type 561A CRT.
c, Reset mV/DIV VARIABLE to CALIB.
4. Check Position Range
Requirement-Proper operation and range of POSITION
control.
a. Adjust the mV/DIV VARIABLE for 4 divisions of display
on the Type 561A CRT.
b. Rotate the POSITION control completely clockwise. The
bottom of the display must be above the top graticule line
on the Type 561A CRT.
c. Rotate the POSITION control completely counterclock-
wise. The top of the display must be below the bottom grati-
cule line.
d, Reset the POSITION control to midrange and mV/DIV
VARIABLE to CALIB.
5. Check Diff Balance
Requirement-50,000:1 rejection ratio. Maximum display,
2 Divisions.
a. Reset the following controls:
Type 2A61
INPUT SELECTOR CM
MILLIVOLTS/DIV .05
b. Set the DIFF BAL control on the Type 2A61 for minimum
deflection on the Type 561A CRT.
6. Check Millivolts/div Compensation
Requirement-Optimum square wave response on the lead-
ing edge. See Fig. 5-1.
a. Reset the following controls: