Tektronix 422, Instruction Manual

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Operating Instructions—Type 422 AC-DC
TEST SETUP C HART
General
5. Set the FOCUS control so the vertical portion o f the
trace is as thin as possible.
Fig. 2-8 shows the fro n t panel of the Type 422. This
chart may be reproduced and used as a test-setup record fo r
special measurements, applications or procedures, or it may
be used as a training aid fo r familiarization w ith this instru­
ment.
G E N ER AL O PERATING IN F O R M A T IO N
Intensity C ontrol
The setting of the INTENSITY control may affect the
correct focus of the display. Slight readjustment o f the
FOCUS and ASTIGMATISM controls may be necessary
when the intensity level is changed. To protect the CRT
phosphor, do not turn the INTENSITY control higher than
necessary to provide a satisfactory display. The light filters
reduce the observed light output from the CRT. When using
these filters, avoid advancing the INTENSITY control to a
setting that may burn the phosphor. When the highest in­
tensity display is desired, remove the filters and use the
clear graticule only. Apparent trace intensity can also be
improved in such cases by reducing the ambinet light or
using a viewing hood. Also be careful that the INTENSITY
control is not set too high when changing the T IM E /D IV
switch from a fast to a slow sweep rate, or when switching
to the external horizontal mode of operation.
The Type 422 CRT uses deflection-plate blanking to de­
fle ct the CRT beam o ff the viewing area during retrace time
and when the sweep is not operating. With this type of
blanking system, the CRT cathode is emitting electrons at
the same rate whether a display is produced or not. The
cathode current is determined entirely by the setting o f the
INTENSITY control. For this reason, the CRT may fail
prematurely even though a display has not been presented
if the INTENSITY control is left at a high setting fo r exten­
ded periods o f time. Therefore, to obtain maximum CRT
life, always set the INTENSITY control fu lly counterclock­
wise except when viewing the CRT.
Focus and Astigmatism Adjustment
The follow ing procedure provides a convenient method
o f establishing optimum setting of the FOCUS and ASTIG­
MATISM controls.
1. Set the V O LTS/D IV switch to CALIBR ATE 4 D IV I­
SIONS.
2. Set the T IM E /D IV switch to .5 ms and the LEVEL
control fo r a stable display.
3. With the FOCUS AND ASTIGMATISM controls set
to midrange, adjust the INTENSITY control so the rising
portion o f the display can just be seen.
4. Set the ASTIGMATISM control so the vertical and
horizontal portions of the display are equally focused (not
necessarily well focused).
6. Repeat steps 4 and 5 fo r best overall focus. Make
final check at normal intensity.
Trace A lignm ent A djustm ent
If a free running trace is not parallel w ith the horizontal
graticule lines, set the Trace Rotation adjustment as fo l­
lows: Position the trace to the center horizontal line. A d ­
just the Trace Rotation adjustment (the power supply must
be operated remotely fo r access to this adjustment) so the
trace is parallel with the horizontal graticule lines.
Graticule
The graticule of the Type 422 is internally marked on
the faceplate of the CRT to provide accurate, no-parallax
measurements. The graticule is marked w ith eight vertical
and 10 horizontal divisions. Each division is 0.8 centimeter
square. In addition, each major division is divided into five
minor divisions at the center vertical and horizontal lines.
The vertical gain and horizontal tim ing are calibrated to the
graticule so accurate measurements can be made from the
CRT. The illum ination of the graticule lines can be varied
w ith the SCALE ILLU M control.
Fig. 2-9 shows the graticule o f the Type 422 and defines
the various measurement lines. The terminology defined
here w ill be used in all discussions involving graticule meas­
urements.
Second
vertical
line
Center
vertical
line
Tenth
vertical
line
1 1 1 1 iiii i i i i
M M
t
H
t
M M
Center
horizontal
" line
Fig. 2-9. Definition of measurement lines on Type 422 graticule.
Light Filter
The mesh filte r provided w ith the Type 422 provides
shielding against radiated EMI (electro-magnetic interfer­
ence) from the face of the CRT. It also serves as a light
filte r to make the trace more visible under high ambient
light conditions. To remove the filte r, press down at the
bottom of the frame and pull the top of the filte r away
from the CRT faceplate (see Fig. 2-10).
2-14