Section 5—475
CALIBRATION
Calibration Interval
To assure instrument accuracy, check the calibration of
the 475 every 1000 hours of operation, or every six months
if used infrequently. Before complete calibration, thor
oughly clean and inspect this instrument as outlined in the
Maintenance section of the manual.
Tektronix Field Service
Tektronix, Inc. provides complete instrument repair and
recalibration at local Field Service Centers and the Factory
Service Center. Contact your local Tektronix Field Office
or representative for further information.
Using This Procedure
Outline. To aid in locating a step in the Performance
Check or Calibration Procedure, an outline is given pre
ceding Part I—Performance Check and Part II I—Calibration
procedure.
Performance Check. The performance of this instrument
can be checked without removing the covers or making
internal adjustments, by performing only Part I —
Performance Check. This procedure does not check every
facet of the instrument's calibration; rather it is concerned
primarily with those portions of the instrument essential to
measurement accuracy and correct operation.
Short-Form Calibration. A short-form calibration pro
cedure is provided to the technician experienced with the
475 as guidelines for calibration of this instrument, in Part
II—Short-Form Calibration.
Calibration Procedure. Completion of each step in Part
III—Calibration procedure, ensures that this instrument
meets the electrical specifications given in the front of this
manual. Where possible, instrument performance is checked
before an adjustment is made. For best overall instrument
performance when performing a complete calibration pro
cedure, make each adjustment to the exact setting, even if
the CHECK— is within the allowable tolerance.
Partial Procedures. A partial check or adjustment is
often desirable after replacing components or to touch up
the adjustment of a portion of the instrument between
major recalibrations. To check or adjust only part of the
instrument, set the controls as given under the nearest
Control Settings and use the Equipment Required list
preceding the desired portion of the step. To prevent
unnecessary recalibration of other parts of the instrument,
readjust only if the tolerance given in the CHECK— part of
the step is not met. If readjustment is necessary, also check
the calibration of any steps listed in the INTERACTION —
part of the step.
TEST EQUIPMENT REQUIRED
General
The following test equipment and accessories, or its
equivalent, is required for complete calibration of the 475.
Specifications given for the test equipment are the mini
mum necessary for accurate calibration. Therefore, some of
the specifications listed here may differ from the actual
performance capabilities of the test equipment. All test
equipment is assumed to be correctly calibrated and
operating within the listed specifications. Detailed opera
ting instructions for the test equipment are not given in this
procedure. Refer to the instruction manual for the test
equipment if more information is needed.
If only a Performance Check procedure or a Calibration
procedure is performed, not all of the listed test equipment
will be required. Items used only for the Calibration
procedures are indicated by footnote 1. The remaining
pieces of equipment are items common to both a Perform
ance Check procedure and a Calibration procedure.
Special Calibration Fixtures
Special Tektronix calibration fixtures are used only
where they facilitate instrument calibration. These special
calibration fixtures are available from Tektronix, Inc. Order
by part number through your local Tektronix Field Office
or representative.
Calibration Equipment Alternatives
All of the listed test equipment is required to completely
check and calibrate this instrument. However, complete
checking or calibration may not always be necessary or
desirable. The user may be satisfied with checking only
selected characteristics, thereby reducing the amount of
test equipment actually required.
The Performance Check and Calibration Procedures are
based on the first item of equipment given as an example of
applicable equipment. When other equipment is substi
tuted, control settings or calibration setup may need to be
altered to meet the requirements of the substitute equip
ment. If the exact item of test equipment given as an
example in the Test Equipment list is not available, first
check the Specifications column carefully to see if any
other equipment is available which might suffice. Then
check the Usage column to see what this item is used for. If
used for a check or adjustment that is of little or no
importance to your measurement requirements, the item
and corresponding step(s) can be deleted.
5-1
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