Louis, KE5GIU asked: Have been lurking here for a while soaking up some wisdom in anticipation of receipt of my K2. As I lost all of my tools etc. in Katrina, I'm in the process of "re-stocking," including a new digital multimeter. I've poked around on the net some, but the choices are truly bewildering. If anyone could offer a suggestion for a unit with a good price-performance ratio, I'd certainly appreciate it.
-------------------------------------------- I've used a Fluke for years. Good and relatively expensive, and rugged. But there are good alternatives. A few years ago my Fluke suffered a minor mechanical failure. While waiting for a replacement part I happened to notice a Radio Shack DMM for about $80. Not only did it do the standard volts, ohms, amps thing, it had a capacitance meter and temperature probe. I bought it on impulse. After getting the Fluke back into working condition, I ran a bunch of tests. The two meters are within 2% of each other; less than 1% on most ranges and measurements. That's not too surprising. The chips that run those things are mass-produced, as are the voltage divider networks for the various ranges. Modern manufacturing offers a precision for pennies that we couldn't buy at any price not too many years ago. The difference that I noticed was in the speed. The Fluke is virtually instantaneous. The RS meter takes a few seconds to display the value. That seems to be one of the big differences in meters. The faster I.C.s cost significantly more than the slow ones, so they go in the more expensive meters. By the way, the capacitance test in the RS meter is amazing. Although it has about 100 pF "parasitic" capacitance - that is, it reads about 100 pF with nothing connected, it is accurate to within a couple of percent all the way down to 10 or 20 pF by simply subtracting the parasitic value. Of course, it goes way up into the many microfarads to check electrolytics at the other extreme. That makes it ideal for sorting out caps of all values though. Another difference between cheap and expensive meters is in the number of digits they display. Many cheaper meters have 3 or 3-1/2 digit displays. That's good enough for many things, but you'll sometimes want to see more resolution than that. A full four digit display is a good investment. Related to the number of digits and speed is the ability of the meter to follow a change in voltage or current as you adjust a circuit. Although the RS meter takes a few seconds to update the digital display, it has a bar-graph that moves quickly to show when a null or peak in an adjustment is reached. Smaller, cheaper meters often omit this feature, making them virtually useless for such peaking or nulling adjustments unless one has a lot of patience! (Personally, I hate all those displays. I still keep an old-fashioned VOM with a wiggly-needle meter in it that I use when I can for such adjusting. But sometimes the high input impedance of the DMM is essential.) Finally, there's mechanical ruggedness. Meters like the Flukes are designed to take a beating, especially if you buy the protective boots that are available. I'm not so sure the cheaper ones would survive as well. So far I've managed to avoid dropping either one of them, so I can't offer any personal experience there. Ron AC7AC _______________________________________________ Elecraft mailing list Post to: Elecraft@mailman.qth.net You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com
