Tektronix Type Z Instruction Manual page 26

Calibration — Type Z
connectors. Make certain the VAR. ATTEN. control is set
fully clockwise. et the GAIN ADJU T control (R8639) to
obtain exactly 4 cm of vertical deflection. Place the Mode
switch to — B ONLY. Check to see that there are exactly 4
cm of vertical deflection.
8. Operational Checks
Perform the following Z Unit operational checks:
(a) Disconnect the calibrator signal from the input con ­
nectors. Check to see that the baseline does not shift
more than 2 mm after switching the Mode switch from
A ONLY to — B ONLY. Reconnect the calibrator signal
to the input connectors.
(b) With the Mode switch at — B ONLY, check the opera ­
tion of the B AC-DC switch by setting it to the AC posi ­
tion. Observe the signal to see that it shifts to its average
voltage level. The shifting of the signal indicates that r he
AC-DC switch and the blocking capacitor function properly.
et the Mode switch to A ONLY and check the A AC-DC
switch for the same waveform shift indication. Place both
AC-DC switches back to the DC position.
(c) Check operation of the VAR. ATTEN. control. When
the control is rotated fully counterclockwise, the vertical de ­
flection of the signal should not exceed 1.6 cm. Rotate the
control back to the fully clockwise position.
9. Turret Attenuation Ratios
With the Mode switch at A ONLY, check for 2 cm of
vertical deflection at each position of the A VOLT /CM
switch by following the information in Table 5-2.
TABLE 5-2
VOLT /CM witch
etting
.05
.1
.25
.5
1
2.5
5
10
25
After checking the A VOLT /CM turret attenuator, set
the Mode switch to — B ONLY and check the B VOLT /CM
attenuator in the same manner.
10. Differential Balance
et the Mode switch to the A-B position and both
VOLT /CM switches to .05.
a 100-volt output signal.
controls for a stable display. Ignoring the spikes on the
waveform, adjust the DIFF. BAL. control for minimum square ­
wave amplitude. The maximum allowable amplitude is
0.5 mm. When the control is correctly adjusted and the Z
Unit balances properly, the waveform appears as a straight
line with positive and negative spikes.
5-4
Calibrator Output
Volts
.1
.2
.5
1
2
5
10
20
50
et the calibrator switch lor
et the oscilloscope triggering
An ac mismatch between two tubes or components can
cause the straight line segments of the waveform to tilt
diagonally to form a zigzag pattern. The amplitude of the
tilt at its highest point should not exceed 1 mm. To check
the amplitude, free run the sweep at 20 millisec/cm and
observe the width of the trace. It should not exceed 1.5 mm
(amplitude of tilt and square wave together). After com ­
pleting this check, repeat step 5. Then go on to step 11.
11. Characteristic Unbalance
Disconnect the signal from the Z Unit inputs, and set
the Mode switch to the TE T position.
Time/cm switch to .5 millisec/cm.
trace, move the COMPARI ON VOLTAGE Polarity switch
to the +, 0, and — positions several times. The overall
baseline shift should not exceed 1 cm. Leave the COM ­
PARI ON VOLTAGE Polarity switch in the 0 position at
the conclusion of this step.
12. nput-Capacitance Standardization
Loosen the set screws in both VOLT /CM knobs with a
0.05" alien wrench and remove the knobs. This allows ac ­
cess to the attenuator adjustments through slots in the front
panel. Each position of the VOLT /CM control has a
HUNT and a ERIE adjustment. The only exception is the
.05 position which has only an input-capacitance trimmer
accessible through the ERIE
Connect the 52-ohm cable to the Type 105
Generator, or equivalent. Connect the other end of the
cable to the 5-to- 1 " L" pad. Connect the other end of the
"L" pad through the 24- μμ f capacitance standardizer to
the A input connector on the Z Unit.
to A ONLY and both VOLT /CM switches to .05.
To make this adjustment, set the square-wave generator
to produce about 3.5 cm of deflection at a frequency of
1 kc. et the oscilloscope front-panel controls for " double
triggering" as follows:
Triggering Mode
Trigger lope
Trigger Level
tability
Time/cm
Rotate the Variable Time/cm control slowly counterclock ­
wise until you obtain a stable display of overlapping square
waves as shown in Fig. 5-5.
Adjust the input-capacitance trimmer in the A VOLT /CM
attenuator for best flat top on the displayed waveform
(see Fig. 5-5), disregarding any fast-rise leading edge spikes.
et the Mode switch to — B ONLY. Disconnect the signal
from the A input connector and connect it to the B input.
Adjust the input-capacitance trimmer in the B VOLT /CM
attenuator for best flat bottom, disregarding the spikes.
13. Output Voltage Divider Compensation
Increase the square-wave generator frequency to 10 kc.
et the oscilloscope Time/cm switch to 50 μ sec and re ­
adjust the Variable Time/cm control to obtain a stable
display of several overlapping waveforms. Adjust the out ­
put voltage divider compensations C7655 and C8655 for
et the oscilloscope
While observing the
side of the slot.
quare-Wave
et the Mode switch
AC Fast
+ Internal
0
Fully clockwise
.5 Millisec