Calibration— Type 544/RM544
NOTE
The following hints should help you to obtain the
best results in checking and adjusting the time-base
sweep rates:
It is quite difficult to detect small sweep rate errors
on the order of 1 or 2% unless measurement is
made using most of the graticule width. It is there
fore recommended that the sweep rates be checked
for correct linearity and timing using the center 8 cm
and the middle 80% of the display as shown in Fig.
5-7. With the measurement taken over a distance of
8 cm, the adjustment can be made more accurately.
Further on in the procedure when you check the
non-adjustable sweep rates, a 1.6 mm error would
indicate a 2% sweep-rate error as shown in Fig.
5-7. The marker peak provides an excellent refer
ence point, particularly if the amplitude is such that
the base line is below the crt viewing area and the
tips of the markers are located in the center of the
crt. When using the sine waves for markers at the
higher sweep rates, set the TU-7 Variable and Ver
tical Position controls so the lower half of the
display is positioned below the crt and the tips
of each cycle are near the center of the crt. By
increasing the amplitude of the display in this
manner each marker or cycle tip appears much
narrower.
The adjustable sweep rates should be set for maxi
mum accuracy. When adjusting the timing capaci
tors, use a screwdriver having a metal tip and a
non-metallic shank to minimize capacitance disturb
ance to the circuit. This will also lessen the chance
of accidentally grounding connections elevated
above or below ground.
19. Adjust X I CAL (XI Sweep Calibration) R566—
Horizontal Amplifier
a. Set the HORIZONTAL DISPLAY switch to NORMAL.
b. Adjust the XI CAL R566 control (see Fig. 5-2) so the
1-msec markers are spaced 1-cm apart and so the
1-msec markers at the 1-cm and 9-cm points coinc ide
with the graticule lines.
20. Adjust X I00 CAL (X100 Magnified Sweep
Calibration) R565
a. Set the time-mark generator for a 10-^.sec time-
marker output.
b. Set the HORIZONTAL DISPLAY switch to XI00.
c. Adjust the TU-7 Variable control so the markers are
about 3 cm in amplitude.
d. Adjust the TRIGGERING LEVEL control for stable trig
gering on the markers.
e. Adjust the XI00 CAL R565 control (see Fig. 5-2) for
one marker per cm.
21. Check X50, X20, X5 and X2 Sweep-Rate Timing
Accuracy
Using Table 5-6 as a guide, check the X50, X20, X5 and
X2 magnified sweep-rate timing. Tolerance is ±5% or
± 4 mm for the center 8-cm portion of the display.
Fig. 5-7. Determining sweep-rate accuracy.
TABLE 5-6
HORIZONTAL DISPLAY
Time-Mark
Switch Setting Generator Output Markers/cm
X50
10 jusec 2
X20
50 jxsec
1
X5
100 /xsec 2
X2
500 /msec 1
22. Adjust SWP/MAG REGIS (Sweep/Magnifier
Registration) R569— Horizontal Amplifier
a. Set the time-mark generator for 100-^.sec and 5-msec
time-marker output.
b. Set the HORIZONTAL DISPLAY switch to NORMAL.
c. Adjust the TU-7 Variable control so the display is
about 4-cm in amplitude.
d. Adjust the TRIGGERING LEVEL control to obtain a
stable display.
e. Using the HORIZONTAL POSITION control, position
the center 5-msec marker to the graticule center.
f. Set the HORIZONTAL DISPLAY switch to XI00.
g. Repeat step (e). Carefully position the 5-msec marker
so the very tip coincides accurately with the center
graticule line.
h. Set the HORIZONTAL DISPLAY switch to NORMAL.
i. Adjust the SWP/MAG REGIS R569 control (see Fig.
5-2) so the center 5-msec marker coincides exactly
with the graticule centerline. Repeat steps (e) through
(i) until there is minimum movement of the center
5-msec time marker as the HORIZONTAL DISPLAY
switch is changed from XI00 to NORMAL.
f. Since adjustments R544, R566, and R565 interact, re
peat steps 18 through 20 for best timing accuracy.
@
5-9
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