What do you all think of this DMM? (Mastech MS8226T)

[Atomic_Chicken]

Greetings!

I've been shopping around the last few days for a DMM. I already own a benchtop Fluke, and a Fluke 77 - both of which perform perfectly for 99% of my measurement needs. However, I've been wanting to buy a DMM that has a computer interface, so I can chart battery runtimes and flashlight output-vs-time graphs... and found this one:

http://www.multimeterwarehouse.com/MS8226T.htm

It seems to have everything I could ever need - true RMS, frequency counter, temperature probe, meter backlighting, and capacitance measurement. It seems almost too good to be true, considering the $79.99 price... it's undoubtably a Chinese special of some kind. On the otherhand, the accuracy specs seem decent, and it does include the software and interface to perform the main function I'm after - data logging on a PC.

Does anyone here have any experience with this, or other Mastech meters? What do you think... would I be throwing my money away, or is this a decent investment for a low-cost data logging meter? I don't want to spend $400+ for a Fluke with an interface, and most of the other PC interface meters I've looked at seem pretty lame by comparison to the Mastech.

Thanks in advance!
Bawko

 

[HCaul]

I personally had a terrible experience with a Mastech meter (not this model, but seemed to have everything but the logging and the frequency counter). It was just not reliable, occasionally giving nonsensical readings. I bought it to have a cheap meter when I didn't want to risk damaging or losing something more expensive, but in this case that turned out to be a bad choice (the low reliability made it useless, since I'd need a reliable one as a backup anyway). Now, that's not to say these are uniformly terrible - defects happen - but my experience wasn't good.

Is your only application data logging? Be sure you can get the data in a form you can use and aren't limited to their software, etc. You might also want to consider a used bench meter (like an HP/Agilent) with a computer interface. You can often find older models on ebay for a song. They will likely be past their calibration date, but are still generally much more accurate than one of these DMMs, and MUCH more flexible. What you generally give up is portability (they are large and require AC power), and high energy (Cat III/Cat IV) protection (which isn't generally available for lab grade stuff that doesn't run exclusively on batteries).

 

[eluminator]

I have a Mastech MAS345 that has the computer interface. I bought it several years ago and it still works fine. I haven't used the computer interface much. It's been so long since I used that, I don't remember much about it.

Anyway, my Mastech is okay. It's not quite as fancy as the one you are looking at but it's half the price. Probably the only thing mine is missing that I might use is the 400 millivolt scale.

I think the DC voltage reading is about 0.7 percent high which is a bit out of spec. but it's rarely an issue. When it is, I use my UEI DMM. You of course would use a Fluke.

Here is the one I have. There is a link there where you can download a zip file that apparently gives you an idea about the PC software. I haven't downloaded it though.
http://elexp.com/tst_s345.htm

 

[jimjones3630]

Can someone please tell me which DMM can capture peak start up amps?
Would it read the peak then hold it on the display or need to be hooked up to computer to read the peak amps?

Thanks, Jim

 

[HCaul]

Can someone please tell me which DMM can capture peak start up amps?
Would it read the peak then hold it on the display or need to be hooked up to computer to read the peak amps?

Thanks, Jim

Well, it depends on what you mean by "peak." In particular, how long a peak?

The surge load of most devices is near infinite (limited only by the resistance of the power source, and in fact slightly negative), but for only a short period and consisting of very little total energy. A single "peak" number doesn't mean anything. A 125 Watt lightbulb (which draws 1 Amp in the steady state) might, depending on where in the cycle it is turned on, draw an average 50 amps for a nanosecond (not long enough to trip a 10 amp breaker or fuse), 10 amps for an early microsecond, decreasing steadily as it converges toward its nominal load (I'm making up these numbers, but you get the idea). But hardly anyone cares about a nanosecond-long peak. There's not enough energy to heat anything up (and so the fuse stays intact) and not enough time to cause a noticable voltage drop in other devices attached to the same source.

The ONLY generally meaningful way to analyze a surge load is with an oscilloscope. Various DMMs can do peak "max" readings that give you an average of over their sampling time. Some have special "fast" modes. For example, the Fluke 89IV/189 can be made to capture maximum and minimum transients over 250µs; shorter peaks will have only inderminate effect on the displayed value. But even this isn't designed for measuring startup surge loads.

So how to measure depends on why you care about the surge value. A quick, cheap, and very effective way I've measured surge current in one-off devices I've designed is by substituting fuses of various values to find the smallest that doesn't blow. (Use fuses of the repsonse time you care about).

H. Caul

 

[mdocod]

I've had the same mastech I bought when I was 15, it was a $20 unit. got it from partsexpress. It still has the same 9V battery in it that it had when I bought it. works fine.

 

[Handlobraesing]

Is it just me or did anyone else thought this is an intellectual property rip-off of a Fluke 189? Look at the design.

 

[wptski]

Well, it depends on what you mean by "peak." In particular, how long a peak?

The surge load of most devices is near infinite (limited only by the resistance of the power source, and in fact slightly negative), but for only a short period and consisting of very little total energy. A single "peak" number doesn't mean anything. A 125 Watt lightbulb (which draws 1 Amp in the steady state) might, depending on where in the cycle it is turned on, draw an average 50 amps for a nanosecond (not long enough to trip a 10 amp breaker or fuse), 10 amps for an early microsecond, decreasing steadily as it converges toward its nominal load (I'm making up these numbers, but you get the idea). But hardly anyone cares about a nanosecond-long peak. There's not enough energy to heat anything up (and so the fuse stays intact) and not enough time to cause a noticable voltage drop in other devices attached to the same source.

The ONLY generally meaningful way to analyze a surge load is with an oscilloscope. Various DMMs can do peak "max" readings that give you an average of over their sampling time. Some have special "fast" modes. For example, the Fluke 89IV/189 can be made to capture maximum and minimum transients over 250µs; shorter peaks will have only inderminate effect on the displayed value. But even this isn't designed for measuring startup surge loads.

So how to measure depends on why you care about the surge value. A quick, cheap, and very effective way I've measured surge current in one-off devices I've designed is by substituting fuses of various values to find the smallest that doesn't blow. (Use fuses of the repsonse time you care about).

H. Caul

I know that you are refering to DC surge current but there are sevaral current clamp meter on the market that capture AC surge current comparable to a scope using a current clamp probe. Are you refering to using a scope with a current clamp probe or a shunt resistor?

 

[HCaul]

I know that you are refering to DC surge current but there are sevaral current clamp meter on the market that capture AC surge current comparable to a scope using a current clamp probe. Are you refering to using a scope with a current clamp probe or a shunt resistor?

Well, inrush/surge current isn't meaninfully expressed as a single number, so you'd have to know the interval over which such a current clamp measures to know what it's actually measuring (and any surge of shorter than that durration may not be reflected in the displayed number), just as with a DMM with a "max" function. (I believe there are clamp meters with built-in scopes, in which case you can see something more than a single number, but that's just two devices in one package).

You can see the inrush current curve on a scope with either a shunt or a (voltage transducer) current clamp; either will work (although I believe most voltage transducer clamps have a minimum respose time of their own that's greater than that of using a shunt).

H. Caul

 

[wptski]

Well, inrush/surge current isn't meaninfully expressed as a single number, so you'd have to know the interval over which such a current clamp measures to know what it's actually measuring (and any surge of shorter than that durration may not be reflected in the displayed number), just as with a DMM with a "max" function. (I believe there are clamp meters with built-in scopes, in which case you can see something more than a single number, but that's just two devices in one package).

You can see the inrush current curve on a scope with either a shunt or a (voltage transducer) current clamp; either will work (although I believe most voltage transducer clamps have a minimum respose time of their own that's greater than that of using a shunt).

H. Caul

I've used a Fluke i1010 clamp probe with Fluke 199B and a 189 DMM measuring inrush on AC motors. They are very close to eachother within a few amps. I have a AEMC F05 clamp meter that measures AC inrush with the ability to view the results at .5, 1, 2.5 and 10 periods. At .5P, it reads approx. the same as the Fluke i1010/199B combo.

Some other current clamp meters manufactures claim to use 1, 10 and 100ms timebase for inrush.

 

[HCaul]

I've used a Fluke i1010 clamp probe with Fluke 199B and a 189 DMM measuring inrush on AC motors. They are very close to eachother within a few amps. I have a AEMC F05 clamp meter that measures AC inrush with the ability to view the results at .5, 1, 2.5 and 10 periods. At .5P, it reads approx. the same as the Fluke i1010/199B combo.

Some other current clamp meters manufactures claim to use 1, 10 and 100ms timebase for inrush.

I've used that combination (the Fluke DMM, scope, and i1010, not the AEMC) as well, and you're definitely limited by the response time of the i1010 (which Fluke doesn't seem to specify) in what you can see. I'd bet if you looked at the same load with a faster clamp (or a shunt) you'd see more a difference between the peak on the scope and the value on the DMM.

Also, of course, with AC loads at commercial power frequencies, the instantaneous peak inrush current can depend very much on when in the cycle it occurs, since we're talking about intervals much shorter than one cycle period. But, as I mentioned, these short peaks are of little significance for most practical purposes, so the fact that they're difficult to measure doesn't matter.

H. Caul

 

[wptski]

I've used that combination (the Fluke DMM, scope, and i1010, not the AEMC) as well, and you're definitely limited by the response time of the i1010 (which Fluke doesn't seem to specify) in what you can see. I'd bet if you looked at the same load with a faster clamp (or a shunt) you'd see more a difference between the peak on the scope and the value on the DMM.

Also, of course, with AC loads at commercial power frequencies, the instantaneous peak inrush current can depend very much on when in the cycle it occurs, since we're talking about intervals much shorter than one cycle period. But, as I mentioned, these short peaks are of little significance for most practical purposes, so the fact that they're difficult to measure doesn't matter.

H. Caul

I used the i1010 with a 87V but those results weren't inline with the 189 or 199B. I then tried a MeterMan CT238 20A current clamp probe on smaller load and that proved to be much closer to the 189/199B reading on the 87V.

I just got 100A/100mv shunt from the link that you provided, I think, at RC Electronics but haven't had time to fool with it yet!

 

[Atomic_Chicken]

Greetings!

Thank you all for the (rather mixed...) feedback on the Mastech!

Since it's either that or buy a $400 Fluke, and since I already have two Flukes that are doing everything I need from precision/quality meters... and the only thing I want of the logging meter is light output vs. time and battery voltage vs. time graphs, I've decided to go ahead and purchase the Mastech. I'll post a brief review on this thread once I've received it and taken it for a spin.

Best wishes,
Bawko

 

[Atomic_Chicken]

Greetings!

I have received the Mastech MS8226T meter. So far, my impressions are very favorable... it seems to be pretty close to my Fluke 77 in terms of DC voltage accuracy (they differ slightly... but only by a few hundredths of a volt).

I installed the logging software on one of my computers, hooked up the cable, and did a few quick "test runs" with a lab supply to vary the voltage by hand. This function worked perfectly, and I REALLY, REALLY like the fact that the RS-232 interface to the meter is optically isolated - less chance of killing your computer when you do stupid stuff with the meter! I like the fact that you can save the data to disk - for manipulation it with other programs.

Overall - I'm very pleased, this meter looks like it will do everything that I need for flashlight data logging, at a fraction of what a Fluke 189 would have cost me. Build quality isn't the best - but it seems quite adequate, and better than most Chinese instruments I've seen in the past.

I know this isn't much of a review, but it should hopefully be enough to help someone deciding whether or not to purchase this meter.

Best wishes,
Bawko

 

[NA8]

After looking at that 3999 LCD display, I noticed in the meter specs that the voltage ranges are 4volts and 40volts full scale. Good for battery (1.5v) measurements, but maybe not so good if your main interest is in the 5-14 volt range.

Nice review, though. Thanks.

 

[lowatts]

Bawko - now that you've had this for a month, are you still positive about it? Time to replace my over 20 year old Radio Shack analog meter. I just ordered one of these, but can cancel if I have to. Have you tried the temperature measurements, that's a useful function to me. Thanks.

 

[Atomic_Chicken]

Greetings!

Bawko - now that you've had this for a month, are you still positive about it? Time to replace my over 20 year old Radio Shack analog meter. I just ordered one of these, but can cancel if I have to. Have you tried the temperature measurements, that's a useful function to me. Thanks.

Yes... I'm still pleased with mine, I've ordered another one so I can do voltage vs. light-output graphs (I'll need to measure both simultaneously...).

If it were my only meter, I'd try to get together a little more $$$ and buy a Fluke, but as an entry-level or budget meter the Mastech 8226T seems to do just fine! No complaints about any part of it so far... it seems to be a fairly well-built and accurate meter at a reasonable price.

As to your other question, yes... the temperature measurement works fine, but the reading can take a little time to "settle" when placed on an object.

Best wishes,
Bawko