Mastech MS8268 Digital AC/DC Auto/Manual Range Digital Multimeter Meter

In the middle of a power outage from Hurricane Sandy, the rusty governor spring on my generator finally broke leaving the engine running at idle. Fashioning a replacement spring and adjusting the generator output to 120 volts got us through the outage, but after it was over I wanted to set the governor more precisely to get exactly 60 Hz. I was planning to buy a dedicated panel-mount frequency meter but discovered that many multimeters now include a frequency function, and since the Mastech was under $30, I ordered it. It arrived two days later, a day faster than promised.My first impressions on opening the box were: 1) it's big, and 2) it's decent quality. The rotary dial and the pushbuttons click into place with authority, the case feels solid and doesn't flex, and the probes are heavy gauge wire. I ran through some AC and DC voltage and resistance checks; the results agree with my other meter though I don't have a NIST-traceable reference to test its absolute accuracy. House power frequency reads 59.96 Hz, as expected. The manual briefly describes the Cat II and Cat III safety standards the meter claims to meet - I have no way to verify compliance but it feels like it could take a beating in a lineman's toolbelt with no problem. A few minor observations that haven't been covered in other reviews:1) It takes some effort to insert the probes the first time. I pushed until they felt fully seated, but there was still 1/4 inch of plastic sleeve exposed and the LED indicators didn't go out. The sockets are a standard size and the probes from my other meter went in smoothly all the way and extinguished the LEDs, so I forced the new probes all the way in. After that they are still stiffer than my old probes but no longer require excessive force.2) The LCD display has a good viewing angle range in reflected light, but when using the backlight it is washed out when your eye is above 90 degrees from the display. The display contrast isn't user adjustable, but the default is fine from anywhere without the backlight and from below 90 degrees when using the backlight.3) You can't set the backlight to stay on - it always fades out after 5 seconds from pressing the light button. But there is a display hold button, so if you are operating in a dim area you could capture the reading you want using hold and then light the display to read it.4) There are two different ways of reading frequency. You can measure AC voltage or current using the function dial and then press the frequency button to cycle between voltage, frequency, and duty cycle. Or you can select frequency on the function dial and switch between frequency and duty cycle with the button. The manual indicates that the available ranges are different depending on whether the dial is set to voltage/current or to frequency, but either way works fine for 60 Hz power.5) Other reviews said the beeper is weak; it sounds fine to me. But when using the continuity test function it has an odd stutter sound when making a connection - be-be-beeeeeeeep. Nothing to worry about, just an indicator that there is some electronics involved rather than a simple battery and beeper connected directly to the probes.All in all a great meter; far more than I expected. Other reviewers say "great meter for the money" but in my opinion it's a great meter, period. The Fluke 175 claims .15%+2 accuracy for DC volts and 1.0%+3 for AC volts; this meter claims .7%+2 DC and .8%+3 AC on most ranges which is more than I need. I'll still use my old multimeter most of the time because it is more compact to carry around (I posted a picture for size comparison with the Equus 3320 Auto-Ranging Digital Multimeter). But it's nice to have the Mastech for when I need the extra features.

After doing a LOT of internet research I decided on this DMM since it had the most features for the best price, and the reviews were consistently good, except for a few very negative ones.First let me say that nearly every DMM on Amazon has at least some very negative reviews. It seems that no matter how well made a DMM is, there will always be some that are defective, or some users who don't know what they're doing and fly off the handle in rage in their review. Reading some of the negative reviews for this Mastech MS8268, it seems very likely to me that many of those reviewers didn't know how to properly use this particular DMM. Every DMM is slightly different, and even if you have experience with another brand and model, you may still have to read the directions for this one.Also because this one is so inexpensive many people may assume it is broken when actually they just aren't operating it correctly. If they spent $300 on an expensive model and it didn't work, they would be much more likely to read the manual better and assume they were doing something wrong. So there can be selection bias at work, especially if we've already read some negative reviews on the item.For instance, I initially thought the continuity function was broken because I'd read some reviews where others had that problem and mine wasn't giving the alert sound when I turned the dial to continuity and placed the leads together. Then I read the manual and found that I also had to press the select button to test for continuity. I did that and it worked perfectly.Also, the digital display will fluctuate wildly when the leads are not touching anything. This is normal.Also, when testing voltage be aware that this meter is auto-ranging, so it will automatically display a reading anywhere from volts to millivolts. In other words, you may test a 9v battery and get a reading of 300.21 You may wonder how a 9v battery could possibly have 300 volts! But if you look more closely you will notice that the volts has changed to millivolts. In other words the battery is so dead that there isn't even a single full volt left in it and the meter is only picking up 300 millivots left in the cell.Basically what I'm saying here is you may want to be careful and patient and educate yourself on using DMMs in general and this one in particular before you create and unnecessary hassle for yourself by returning this one as a piece of junk.There are lots of good video tutorials on Youtube for learning how to use a DMM. I recommend taking some time with them and also reading the manual for this one if you run into problems. If all of that fails, then maybe you truly do have a defective one. Mine however is working perfectly for testing continuity and voltage in both AC and DC. Build quality seems indistinguishable from other professional quality tools I have used.I'm very pleased with this purchase and recommend it to others.