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5700A/5720A Series II Calibrator
Service Manual
1-8
when the calibrator is returned to a standards laboratory for periodic verification. The
5700A/5720A Series II Service Manual contains the wideband flatness calibration
procedure. Chapter 7 of this manual contains the wideband gain calibration procedure.
1-14. Service Centers
A worldwide network of Fluke service centers supports Fluke instruments and assists
customers in many ways. Most service centers have standards and calibration
laboratories certified by local national standards organizations. The following is a partial
list of the services provided by most service centers:
• Repair and certified traceable calibration of all Fluke products.
• Certified traceable calibration of many non-Fluke standards and calibrators.
• Worldwide exchange of calibrator internal modules. Delivery inside the U.S.A. is
typically within 48 hours.
• Service agreements with the flexibility to suit your needs. These can be a simple
warranty extension or an agreement that includes on-site support. Calibration service
agreements are also available in many areas.
• Training programs and seminars, including laboratory metrology, system
applications, and product maintenance.
• Application help and consulting, including system design, hardware selection,
custom software, site evaluation and installation.
• Replacement parts inventory, including recommended spare parts and module kits.
• Visit www.fluke.com for locations and phone numbers of authorized Fluke service
centers.
1-15. The Components of the 5700A/5720A Series II Calibrator
The calibrator is configured internally as an automated calibration system, with process
controls and consistent procedures. Internal microprocessors control all functions and
monitor performance, using a switching matrix to route signals between modules.
Complete automatic internal diagnostics, both analog and digital, confirm operational
integrity.
Reference amplifiers maintain dc accuracy and stability. Of all technologies available,
reference amplifiers have the lowest noise and best stability. Reference amplifiers in the
calibrator go through special selection processes including long-term aging to ensure
high reliability and performance well within specifications.
The calibrator achieves its exceptional ac voltage accuracy by using a patented Fluke
rms sensor to make real-time ac/dc comparison measurements. The Fluke rms sensor is
similar in principle to the traditional thermal voltage converter, but has a shorter time
constant, virtually no reversal error, higher signal-to-noise ratio, and better frequency
response. In the calibrator, one Fluke rms sensor serves as an ac/dc transfer standard to
develop gain and flatness correction constants during calibration. The second Fluke rms
sensor continuously monitors and corrects output voltage during operation.
A patented 26-bit digital-to-analog converter (dac) provides the calibrator with the
ability to precisely vary its output. This is a pulse-width modulated dac with linearity
typically better than 0.2 ppm of full scale. As with the other internal functions, the
linearity of the dac is automatically checked during calibration and analog diagnostics.