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44
Checking and adjusting
8- Square wave response of step attenuator
Turn R7 fully clockwise.
- To BU4 connect a square wave voltage of a frequency of 2 kc/s.
- Adjust the square wave response according to the table below.
Position SK4
Adjust with
0.1 V/div.
C727(Fig. 19)
0.3 V/div.
C728(Fig. 19)
1 V/div.
C729 (Fig. 19)
Check the other positions.
9. Frequency response curve
Turn SK4 and R7 fully clockwise.
- Set SK3 to position "30 mV/div.".
To BLJ4 connect a sinewave of a frequency of 2 kc/s and an amplitude
such that the picture width is exactly 8 divisions. If the X sensitivity (see
point E.2) is correctly adjusted, the voltage on BU4 must amount to
about 85 mV.
- Increase the frequency of the voltage on BU4 to 200 kc/s, but keep the
amplitude constant. Now the picture width must be at least 6 divisions.
10. Phase characteristic
- Set SK3 and SK4 to position ".03 V/div.".
- Turn R6 and R7 clockwise.
~ Apply a sinusoidal voltage to BU2 and BU4 of a frequency of 5 c/s.
Both voltages must have the same phase and the same amplitude. Both
voltages must have the same phase and the same amplitude. Now an
ellipse arises on the screen. In the way described in Chapter "Phase
measurements", determine the angle <p which the ellipse makes with the
X axis. The deviation from 35° must not exceed 5°.
- Repeat this measurement at frequencies of 100 kc/s and 200 kc/s,
Tolerance 5°.
11. Hum in the X amplifier
With SK4 in position ".03V/div" the hum in the X amplifier must not
exceed 0.1 division.
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