Ver Tical System; C H E C K /A D Ju S T Step Attenuation Balance; Check/Adjust Vo Lts/Div Var; Check/Adjust Probe Compensation - Tektronix 221 Instruction Manual

Equipment Required
1. Probe tip to BNC adapter
2. Standard amplitude calibrator
3. Constant amplitude signal generator
Control Settings
Preset the controls as given in the Preliminary Control
Settings,
10. Check/Adjust Step Attenuator Balance (STEP
BAL)
a. Set the VO LTS/DIV switch to the 1 V position.
b. Position the trace to the horizontal center line.
c. Change the VO LTS/DIV switch to the 5 m position.
d. Check that the trace is w ithin 0.1 division of the
center horizontal line.
e. Adjust the STEP ATTEN BAL adjustment, R135, for
a trace at the horizontal center line. See Fig. 5-4.
f. Repeat part (a) through (e) until less than 0.1 division
shift is noted when changing the VO LTS/D IV setting.
11. Check/Adjust V O L T S /D IV V A R BAL
a. Set the trace to the center horizontal graticule line.
b. Set the VO LTS/DIV setting to 0.1 and the VOLTS/
DIV VAR to minimum counterclockwise direction.
c. Check that there is less than 0.1 division of trace shift
when varying the VO LTS/DIV VAR control.
® t
V E R T IC A L SYSTEM
4. Square-wave generator
5. Three-inch screwdriver
6. Low-capacitance screwdriver
d. Adjust the VAR VO LTS/DIV BAL adjustment for a
trace shift for no more than 0.1 division. See Fig. 5-5.

12. Check/Adjust Probe Compensation

a. Set the VO LTS/DIV
COUPLING switch to DC.
b. Connect the square-wave generator to the 221. Use a
probe tip to BNC adapter, a 50-ohm term ination, and a GR
to BNC adapter.
c. Set the square-wave generator for a 5 kHz signal w ith
four divisons of display.
d. Set the SEC/DIV switch to .1 m. Adjust the LEVE L/
SLOPE control fo r a stable display, triggered on the
positive excursion of the waveform.
e. Check that the positive excursion of the displayed
square wave is fla t (flat top).
f. Adjust Cl 12 for the best square-wave display (flat
top). See Fig. 5-4.
g. Leave test equipment connected.
Fig. 5-5. Location of the V O L T S /D IV Var Bal adjustments.
REV. APR 1974
Calibration—221 Service
switch to .1, and INPUT
5-7