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Facts from Fluke on low-cost digital multimeters.
When you're looking for genuine value in a low-cost DMM you have a lot more to consider than price. You need information about ruggedness, reliability and ease of operation.
Accuracy is important. And so are special measurement capabilities. But above all, you must consider the source, and that company's reputation for service and support.
Fact is, as electronics become more a part of our daily lives, dozens of new manufacturers are rushing to market their "new" DMM's. In theory, this is healthy; but in practice, crowding is confusion.
To help you deal with this flood of new products, here are some facts you should know about low-cost DMM's.
The economics of endurance.
Even the least expensive DMM isn't disposable. Accidents happen, and test instruments should be built to take the abuses of life as we live it.
Look for a DMM with a low parts count for reliability, and rugged internal construction protected by a high-impact shell. Make sure the unit meets severe military tests for shock and vibration.
Another feature to check out is protection against overloading, whether from unexpected inputs, transients, or human errors.
Just for the record, all Fluke low-cost DMM's meet or exceed military specs, and feature extensive overload protection.
The importance of being honest.
Just because a multimeter is digital doesn't mean it's automatically more accurate than a VOM--even though the LCD might give you that impression. The benchmark for accuracy in DMM's is basic dc accuracy. The specs will list it as a percentage of the reading for various dc voltage ranges.
Of course accuracy is more critical in some applications than others, and increasing precision and resolution in a DMM usually means increasing price.
In the Fluke line, you can choose a model with a basic accuracy of 0.25% (the 8022A), others rated at 0.1%, or the new 8050A bench/portable at 0.03%.
Special measurements: getting more from your DMM.
Actually, for all the variations in size, shape and semantics, most DMM's perform five basic measurements: ac and dc voltage and current, and resistance. Prices vary according to the number of ranges and functions a DMM delivers.
The Fluke line includes DMM's with from 24 to 39 ranges, 3 1/2 and 4 1/2-digit resolution, and some unique functions you won't find in any other DMM. Additional measurement capabilities like temperature, dB, conductance and circuit level detection.
If your work involves temperature measurements, the new 8024A delivers direct temperature readings via any K-type thermocouple. This is especially useful in testing component heat rise and checking refrigeration systems.
Another talented instrument is our new 8050A bench/portable. The micro processor-based 8050A features a self-calculating dB mode in which dBm readings are displayed automatic ally referenced to one of 16 selectable impedance ranges--a real timesaver when servicing audio equipment.
And of course no discussion of DMM's is complete without considering conductance--a Fluke exclusive featured on five of our low-cost DMM's--which allows you to make accurate resistance measurements to 100,000 Megohms.
You can't do that with any ordinary multimeter, but it's a must for checking leakage in capacitors and measuring transistor gain.
A handful of efficiency.
When every minute matters, your schedule is tight and so is your work space, you need a portable DMM that's fast and easy to operate.
We designed our handheld DMM's with color-coded in-line pushbuttons for true one-hand operation: no need to hang onto the meter with one hand while twisting a rotary dial with the other.
But there's more to convenience than fingertip control. The 8024A, for example, is also designed to function as an instant continuity tester, with a selectable audio tone to indicate shorts or opens. It also has a peak hold feature to capture transients.
A word about warranties.
Last but not least, look closely at the company that manufactures a low-cost DMM. Their service is just as important as their product. Look for no-nonsense warranties, a large family of accessories, an established network of service centers and technical experts you can rely on.
That's how you'll recognize a knowledgeable supplier of low-cost DMM's, a company with experience, resources and a commitment to leadership in the industry.
Incidentally, you'll find it all at Fluke.
Look for more facts from Fluke in future issues of this publication. Or call toll free 800-426-0361; use the coupon below; or contact your Fluke stocking distributor, sales office or representative.
(source: Electronic Technician/Dealer, Nov. 1979)