Tektronix TYPE Z PLIG-IN Instruction Manual page 7

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Front Panel
A front-panel view of the Type Z Unit is shown in Fig. 2-1.
In addition, a brief functional description is given of the
front-panel controls, input connectors, Securing Rod, and
Mechanical Lock.
Connecting the Z Unit to the Oscilloscope
Connect the Z Unit to the associated oscilloscope by
inserting the unit into the plug-in compartment and tighten­
ing the Securing Rod. With the Intensity control of the
oscilloscope turned fully counterclockwise, switch on the
oscilloscope power. Normally it is necessary to wait a few
minutes for the oscilloscope and plug-in to warm up and
stabilize. Then turn up the intensity and set the oscilloscope
triggering controls to produce a free-running sweep.
tion the trace on the screen using the POSITION control
and the oscilloscope beam-position indicators.
Preliminary Operational Adjustments
After the Z Unit has warmed up and stabilized, check
its operation to see if adjustment of one or more of the
following controls is necessary. Be sure that the oscilloscope
used in conjunction with the Z Unit is correctly calibrated in
the vertical-deflection circuit, and that the calibrator output
voltage is correct.
1. Amplifier DC Balance
If the trace cannot be centered on the screen when the
POSITION control is set near midrange, the AMP DC BAL
adjustment (see Fig. 2-2) must be checked.
adjustment arises mostly when the Z Unit is transferred
from one oscilloscope to another. To make the adjustment,
set the POSITION control to midrange, remove the left
side panel from the oscilloscope, and adjust the AMP DC
BAL control to position the trace behind the horizontal
centerline of the graticule.
2. Differential Balance
Differential balance may be quickly checked by applying
100 volts of calibrator signal to both input connectors. Set
both VOLTS/CM switches to .05, the AC-DC switches to
DC, and the Mode switch to A-B DIFF. Ignoring the positive
and negative spikes, adjust the DIFF. BAL. control to elimin­
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ate any square-wave response (that is, to obtain a straight-
line appearance of the trace).
3. Variable Attenuator Balance
Any vertical shift of the oscilloscope trace when the VAR.
ATTEN. control is rotated, with no input signal applied,
indicates need for adjustment of the variable attenuator
balance. This adjustment must be made in conjunction
with the differential balance adjustment (step 2) due to
interaction between the circuits.
ments until both are correct.
Set the Mode switch to A O N LY and remove any input
signals. Adjust the VAR. ATTEN.
eliminate any vertical shift of the crt trace as the VAR.
ATTEN. control is rotated.
be centered as described in step 1 (Amplifier DC Balance).
If not, repeat step 1.
4. Gain
The gain adjustment should be checked periodically to
assure correct vertical deflection factors. It should also be
checked when the Z Unit is transferred from one oscilloscope
to another. The adjustment is made using the calibrator
signal from the oscilloscope.
Set the Mode switch to A O N LY and apply 200 milli­
volts of calibrator signal to the A input connector. Make
sure the VAR. ATTEN. control is set fully clockwise.
the A VOLTS/CM switch to .05 and rotate the G AIN AD ­
JUST control for exactly 4 centimeters of vertical deflection.
Input Signal Connections
It is often possible to make signal connections to the
Z Unit with short-length, unshielded test leads. This is par­
ticularly true for high-level, low-frequency signals.
such test leads are used, you must also use a ground con­
nection between the oscilloscope and the chassis of the
signal source. (Note: Excessively long test leads may cause
parasitic oscillations.)
In many applications, however, unshielded leads are
unsatisfactory for making signal connections because of
pickup resulting from magnetic fields. In such cases, shielded
cables should be used. You must be sure that the ground
conductors of the cables are connected to the chassis of
both the oscilloscope and the signal source.
In high-frequency work it is usually necessary to terminate
signal sources and connecting cables in their characteristic
Repeat the two adjust­
BALANCE control
Check to see if the trace can
Set
When
2-1
to