There are few instruments as widely used, and whose performance is as critical, as the precision bench digital multimeter (DMM). Precision bench DMMs are used as standalone instruments and in R&D, manufacturing test systems and service operations. They validate the performance of a wide variety of devices and perform functional testing, environment stress screening, troubleshooting and so on. They are a vital component in the process of ensuring product quality and reliability.
More demands are placed on meters today than ever before. They need to be accurate, of course. An instrument that provides inaccurate readings could lead to high rates of potentially faulty products escaping into the field. But today's bench meters must also operate under tighter tolerances, wider ranges and under varying environmental conditions to meet customers' demands for improved performance and quality.
Given the economic realities in today's businesses, engineers are also looking for meters with wider ranges and additional functions that increase the value of the tool. Ease of use is important too, because new employees have to get up and running quickly. It can take a lot for a meter to measure up.
Enter Fluke, known worldwide for accurate, reliable and easy-to-use precision multimeters and calibrators. Through years of experience designing and manufacturing industry standard tools - from handheld meters like the 180 Series to the ultra-accurate and stable 8508A Reference Multimeter - the company has developed a foundation that makes it well-suited for the next step.
The result: A new line of 6.5 digit bench DMMs that offer more accuracy, a broader feature set, and greater utility for production test, research and development applications.
The new Fluke 8846A Bench DMM
The Fluke 8846A provides substantially higher accuracy and precision than other 6.5 digit bench DMMs at an affordable cost. The 8846A offers 6.5 digits of resolution with V dc accuracy to 0.0024 %, 30 % better than the current leading precision bench DMM. The 8846A also offers wider measurement ranges than other high-performance precision bench DMMs, from 10 ohms to 1 gigohms, from 100 micro-amps to 10 amps, from 100 mV ac to 1000 V ac, and from 100 mV dc to 1000 V dc.
These wider measurement ranges deliver an extra digit of resolution to many measurements on the edges of the spectrum. For example, the leading precision bench DMM displays a 5 ohm measurement as 5.0000 in the 100 ohm range, while the new 8846A with a lower 10 ohm range displays it as 5.00000.
These improvements in accuracy and resolution increase measurement confidence and significantly reduce measurement-related errors. In general, the accuracy of the measurement device needs to be equal to or less than one-fourth of the allowable tolerance of the unknown signal in order to eliminate errors introduced by the measuring device itself.. The Fluke 8846A can prevent failures that may go undetected with a less accurate DMM in applications that require high levels of performance such as voltage and current references, voltage controlled oscillators, amplifier feedback loops, and reference resistors, capacitors and other passive components.
Also new: The Fluke 8845A
Fluke is also introducing the 8845A bench DMM, which provides equivalent or better performance at a price up to 20 % less than other leading 6.5 digit bench DMMs. The 8845A provides 6.5 digit primary and secondary readings with accuracy to 0.0035 % V dc. The new DMM also offers 100 ohms to 100 megohms, 100 microamps to 10 amps, 100 mV ac to 750 V ac, and 100 mV dc to 1000 V dc measurement ranges. By offering equal performance at a lower cost, the 8845A can significantly lower the cost of production testing.
Four-wire measurements with two connectors
Both the Fluke 8845A and the 8846A have special input connectors with two conductors per lead that enable four-wire measurements to be made with only two connections, simplifying four-wire testing and eliminating the possibility of connection errors. The special 2x4 wire probes are particularly beneficial in probing small or tightly-spaced components in order to make a precise four-wire resistance measurement, including relay contacts, coils, terminators, connector contacts, reference dividers, and other surface-mount passive components.
Unique graphical display
The two new Fluke DMMs offer a graphical display along with a new user interface that makes them much easier to use than conventional DMMs. Unlike the character-based displays used on most DMMs, the Fluke 8845A and 8846A displays can present any combination of text and graphics.
For example, setting up an interface on a DMM with a character-based display requires scrolling through a series of hierarchical text-based menus until you reach the appropriate setup option and enter the desired parameters. A graphical screen with context sensitive menu structures requires far fewer keystrokes and is much easier to use. For each menu selection, all of the menu choices based on the current position in the menu structure are presented on the screen. The user executes a menu pick with a single keystroke by pushing the function key indicated on screen. No up/down or left/right arrow scrolling required.
The graphical display extends a user's utility with on-screen analysis modes and dual readings.
The graphical displays on the 8846A and 8845A make it possible to reveal signal quality issues such as drift, intermittents and stability. Analyzing a measured values distribution over time can highlight potential, recurring out-of-tolerance and display them in graphic or numeric format provides important new capabilities for diagnosing or validating analog circuits.
The new Fluke DMMs can perform statistical analysis on the instrument itself, saving the time currently required to download data to a personal computer and manipulate it in a spreadsheet or other program. The 8845A and 8846A automatically calculate the minimum, maximum, average and standard deviation of series of readings. The results and the statistical analysis are presented on a single screen, eliminating the need to switch functions and retake measurements.
The 8846A and 8845A can also display line graphs and histograms that can provide new insights into testing results and help detect problems earlier. For example, operators can plot measurement readings as a function of time, using the TrendPlot feature. The TrendPlot paperless chart recorder graphically identifies the extent of drift and other intermittent events in analog circuits. The 8846A and 8845A can also display readings in the form of a frequency distribution plotted on a histogram. The histogram mode often reveals stability or noise problems in analog circuits.
Improved interfacing and storage capabilities
The Fluke 8486A DMM also offers a more streamlined method for downloading results to a personal computer for analysis or comparison than conventional instruments, eliminating the need to install proprietary software. Users can plug a flash memory drive into the USB port of the 8846A and store measurements in a comma-delimited text-based file (CSV). After downloading measurements, the user transfers the memory drive to their PC and opens the file in any program that reads CSV format.
The 8846A and 8845A can be easily incorporated into an existing automated test system. The new Fluke precision DMMs offer the standard RS-232 and IEEE interfaces used on benches and in automated test systems today. And, to stay abreast of new standards, the 8846A and 8845A are also equipped with an Ethernet interface. These meters emulate the user interface and programming commands of the leading bench DMMs, including the Fluke 45 and Agilent 34401. SCPI compatibility and drivers allow them to work with most available application and development languages. Both front and rear inputs are provided to make connections at the most convenient location.
The Fluke 8846A bench DMM offers higher levels of accuracy and resolution than other leading precision DMMs, while the 8845A costs up to 20 % less than other meters delivering the same level of performance. Both of these new DMMs also offer improvements in ease of use, connectivity and display capabilities.