Tektronix Type Z Instruction Manual page 28

Calibration — Type Z
five half cycle of the waveform by using the + Internal
position of the Triggering Mode switch. Adjust L7645, L8645,
L7632, and L8632 to obtain the sharpest negative leading
corner on the displayed waveform without introducing any
overshoot (see Fig. 5-7). Adjust each pair of variable in ­
ductors (for example, L7645 and L8645) in equal increments
so the slugs are positioned the same depth in the coil forms.
Disconnect the signal from the B input connector and
apply it to the A input connector.
to A ONLY. et the oscilloscope Trigger
— Internal to display the positive half cycle of the wave ­
form. Check to see if the leading corner of the positive ­
going waveform is as square as possible without overshoot.
If it is not, adjust the coil slugs for a compromise between
the best display obtained with signal applied to the B
input connector and that obtained when connected to the
A input connector.
the best possible high-frequency differential operation will be
attained.
Disconnect the square-wave generator cable and the
termination.
16. Bandwidth Measurement
Apply a 50-kc sine-wave from the Type 190A Constant-
Amplitude ignal Generator (or equivalent) to B input
connector. et the oscilloscope Time/cm switch to the .1
millisec position and free run the sweep. Adjust the gen ­
erator amplitude control so that the signal produces exactly
28 mm (2.8 cm) of deflection on the crt. Center the display
vertically on the screen.
Increase the sine-wave generator frequency to 13 m c ,
keeping the generator output level constant.
190A Generator maintains a constant-amplitude signal auto ­
matically.)
After the generator frequency has been increased to
13 m c , (3 db point), there should be at least 20 mm (2 cm)
of deflection.
If another type of Tektronix oscilloscope is being used
with the Z Unit to make a bandwidth check, consult the
pecifications section of this manual for the upper frequency
limit. That is the frequency at which 20 mm of deflection
or more should be obtained. For instance, if a Type 535A
Oscilloscope is used in conjunction with the Z Unit, 20 mm
or more should be obtained with the sine-wave generator
set at 10 m c .
Disconnect the generator from the B input connector
and apply the signal to the A input connector.
Mode switch to A ONLY and repeat this step. Disconnect
the sine-wave generator.
17. Precision Voltage Adjustments
Remove the Z Unit and connect an EP54 plug-in extension
between the unit and oscilloscope.
VOLTAGE Polarity switch to + . Make certain the COM ­
PARI ON VOLTAGE Range switch is set to 100 V. Before
proceeding with this step, be sure the regulated power
supply voltages measured in the oscilloscope are within
specifications as noted in the preliminary calibration in ­
structions. Refer to Fig. 5-8 for locations of all test points
and internal adjustments given in this step.
5-6
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et the Mode switch
lope switch to
The compromise setting assures that
(The Type
et the COMPARI ON
CAL. 1
Test Point
ABC
Fig. 5-8. Top view of the Z Unit showing location of step 17 test
points and internal adjustments.
(a) Adjust CAL.
— 107.70 volts and connect it between Test Point A and
ground. Adjust CAL. 1 (R8674) for a null reading on the
meter.
(b) Adjust CAL.
+ 107.70 volts. Place the COMPARI ON VOLTAGE Polar­
ity switch in the — position. Adjust CAL. 2 (R7671) for a
null reading on the meter.
When adjusting CAL. 1 and CAL. 2 wirewound
controls, it is more important that the voltage
readings be identical, than that they be exactly
107.7 volts.
and +107.95 are better than
+ 107.85. Keep the two voltage readings within
the range of 107.3 to 108.1 volts, however.
(c) Adjust CAL. 3: With the precision voltmeter set for
+ 107.7 volts, connect it between Test Point B and Ground.
et the COMPARI ON VOLTAGE Polarity switch to the
+ position. Adjust CAL. 3 (R7681) for a null indication on
the meter. (If CAL. 1 and CAL 2 adjustments are set at
107.9 or any other voltage reading within limitations given
in step 17b, then CAL. 3 should set at the same voltage).
(d) Adjust CAL.
et the
+ 100.00 volts and connect it between Test Point C and
ground. Adjust CAL. 4 (R7684) for a null reading on the
meter.
(e) Adjust CAL. 5:
Range switch to 10 V and the precision voltmeter for
10.000 volts. Adjust CAL. 5 (R7689) for a null reading on
the meter. Because of interaction between CAL. 4 and CAL.
5, repeat these adjustments until readjustment is no longer
necessary.
(f) Check 1 Volt Range:
AGE Range switch to 1 V and the precision voltmeter for
1.0000 volts. The meter should be within 5 millivolts of
null. Or conversely, null the voltmeter by turning the
CAL. 2 CAL. 3 CAL. 5 CAL. 4
Test Point Test Point
1: et the precision voltmeter for
2: et the precision voltmeter for
NOTE
For instance, readings of — 107.90
— 107.70 and
4: et the precision voltmeter for
et the COMPARI ON VOLTAGE
et the COMPARI ON VOLT ­