Section 1V; Performance Tests; Introduction; Equipment Required - HP 3457A Service Manual

SECTION IV
PERFORMANCE TESTS
4-1. INTRODUCTION
4-2. Section IV contains Performance Tests designed to verify the accuracy of the H P
3457A Milltimeter.
Accuracy specifications are listed in Table 1-1 of this manual. This section also contains Operational
Verification Tests which provide a more rapid method of testing the operation and accuracy of the unit.
The Operational Verification Tests are designed to provide a 90n/o confidence that the HP 3457A is opera-
tional and meets specifications. Both the Performance Tests and Operational Verification Tests can be per-
formed without access t o the interior of the instrument.
4-3. EQUIPMENT REQUIRED
4-4. Equipment required for the performance tests and operational verification tests are listed in the
Recommend Test Equipment table in Section I of this manual. Equipment other than that recommended
may be used as long as the critical specifications are met.
4-5. TEST RECORD
4-6.
Results of the performance or operational verification tests may be tabulated on the Test Record lo-
cated a t the end of the respective procedures. The Test Record lists all of the tested specifications and their
acceptable limits. It is suggested that the performance tests or operational verification tests be performed
and the results tabulated when the instrument is received. These results can be used f o r comparison with
periodic calibration results.
4-7. CALIBRATION CYCLE
4-8. This instrument requires periodic performance verification. The frequency at which the instrument
should be tested is dependent upon its usage and the environmental operating conditions. T o maintain 24
hour specifications, the instrument should be checked daily; to maintain 90 day specifications, the instru-
ment should be checked at
90 day intervals. It is suggested that the performance test be performed at
90
day intervals f o r normal operation.
4-9. TEST CONSIDERATIONS
4-1 0. General
4-1 1. Because the HP 3457A is capable of making high accuracy measurements, certain requirements need
t o be made. For example, standards being used t o test accuracy should not introduce any significant uncer-
tainties in the performance tests. A standard which is ten times more accurate than the HP 3457A nearly
eliminates uncertainties. In most cases, standards with these accuracies are not readily available, therefore, a
compromise is necessary. A primary in house standard, one which has been certified by the National Bureau
of Standards (NBS)
and
can supply the necessary outputs, is recommended. If a primary standard is not
available, one of the following may be appropriate:
a. Use a standard which is three or four times more accurate than the HP 3457A specifications t o be
tested. Keep in mind, however, the potential uncertainties these standards may introduce.
b. Use a highly stable calibrated standard and add the correction factors (usually supplied on the
calibration charts) t o the test reading.
c. Send the
HP 3457A t o an HP Service Center or other NBS-certified standards facility for
calibration.