Tektronix M 531, Инструкция по эксплуатации

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Calibration— Type M
Fig. 5 -3 . Adjusting the input capacitance and attenuator compensation: (a ) proper adjustment; (b ) improper input-capacitance adjust­
ment; (c) attenuator over compensated. Sweep rate: 0.5 millisec/cm.
Set the A VOLTS/CM switch to .02 and increase the
output amplitude of the square-wave generator to produce
a deflection of about 3 centimeters on the crt. Set the
MODE switches for the other channels to OFF.
Table 5-3 lists the setting of the VOLTS/CM switch that
connects each attenuator into the input circuit. The capaci­
tor for each setting of the VOLTS/CM switch is listed ac­
cording to the effect it has on the square wave. When
adjustments are properly made, the waveform for each
setting should have an optimum square corner with minimum
hook and flat top, as shown in Fig. 5-3(a). (Some M Units
may exhibit a small amount of hook at one or more switch
positions.) The enlarged illustration of the corner of the
waveform shows the appearance of hook when adjusted
to minimum. Waveforms (b) and (c) in Fig. 5-3 show two
types of waveform distortion that may result from im­
properly adjusted capacitors.
TABLE 5-3
Input-Capacitance Standardization
and Attenuator Compensation
VOLTS/CM
Switch Setting
Affects Top of
Square Wave
Affects Corner
of Square Wave
.02 C5317
.05 C5308B C5308C
.1 C5309B C5309C
.2*
C5310B
C5310C
2**
C5313B C5313C
* Remove 5XT ottenuator.
** Remove both 50-ohm terminations.
Maintain approximately 3 centimeters of vertical deflec­
tion by adjusting the Output Amplitude control on the
square-wave generator each time the VOLTS/CM switch
is moved from one position to the next. In the .2 VOLTS/CM
switch position it will be necessary to remove the 5XT
attenuator to obtain more signal drive to the M Unit. In
the 2 VOLTS/CM switch position, remove both terminations
and connect the cable directly from the generator to the
47-pf Input Time Constant Standardizer. To prevent a signal
shock hazard, turn the DC ON-OFF switch to the OFF
position on the Type 105 before removing the attenuator,
terminations, or applying the signal to the other channels.
After the proper connections are made, turn the Type 105
DC ON-OFF switch to ON and continue with the adjust­
ments.
Disconnect the signal from channel A, and set the A MODE
switch to OFF. Apply the signal to the other channels
and repeat the procedure.
16. Check Square-Wave Response (All Channels)
Set the Output Amplitude control on the square-wave
generator to minimum. Connect the Output connector on the
Type 105 (or equivalent) through a 50-ohm termination, 5XT
attenuator, 50-ohm cable, and another 50-ohm termination
to the channel A input connector. (This is the same setup
shown in Fig. 5-2 except that the 47-pf Input Time Constant
Standardizer is not used.) Set the channel A MODE switch
to DC NORM, and set the MODE switches for the other
channels to OFF. Set the A VOLTS/CM switch to .02. Ad­
just the generator output amplitude for a vertical deflection
of about 3 centimeters. Check the waveform for flat tops, at
the frequencies listed in Table 5-3. The oscilloscope Time/
CM switch setting to use for each frequency is listed in
the table.
5-6