Thursday, May 31, 2012

First impressions of the Mastech MS8226 DMM

Received two of these today.  I haven't used them yet, so take this for what it's worth.

The 8226 comes in the "T" and "non-T" version.  The "T" version is true RMS, which I did not get because I don't care about that for these meters.

The meters are built to the same quality and style as the Mastech MS8218.  In other words, perfectly well, as far as I can tell.  It doesn't look or feel cheaply built.  The boot/case is integral to the unit.  The unit has a separate on/off button, which personally I find rather welcome.

The build commonality extends to the battery cover, which uses simple turn fasteners.  Plus: they're nice to use.  Minus: they're not captive, and I often drop them when changing the batteries.

The versions I got were purchased from GoodLuckBuy, and came in as 9V versions.  Apparently some people have laid their hands on an AA version of this meter - nobody quite seems to know why.

I'm also not sure how.  My 9V versions cannot be converted to AA, as there is simply not enough room in the back of the meter for AA cells.  (AAA cells, maybe, but they're a half-step down from 9V batteries in my book.)  Thus, making an AA version is not just a question of swapping out a different battery carrier into the meter body at the factory.  You would need a completely different body, which seems highly unlikely to me.

I did not bother checking to see if the meter will run on 3V instead of 9V.  Some meters do, but since the AAs cannot be made to fit it's a moot point.

Normally, I would be rooting for getting the AA version - I hate 9V batteries almost as much as I hate AAA batteries.  Something to note, though, is that the 9V version are very easy to power from AC.  Seeing as these are logging meters, and may need to stay on for long periods, inexhaustible power is much more of a requirement.

For these, all you need is a 9V adapter with the right snap connector, which is easy to find.  AA or AAA meters need you to either make fake batteries or to jam wires directly in to the battery tabs - workable, but more hackish, and harder to set up.  So I'll happily take the 9V versions for the ease of mains adaptability.

The 8226s I got have some slight imperfections in the front casing, right next to the "MS8226 DMM" name.  They are hard to spot, but look like mold inserts for optional type-K thermocouples, plainly for a similar but different meter.

Note that this is not a defect so much as a consequence of sharing the same mold between different models of meter.  Still, there is no need to have these features quite so obvious on the meters that do not incorporate the extra slots.  In this sense the build quality is perhaps not up to perfection, but this is a pretty niggling point.

I have not looked inside the meter yet to see if there are any connectors on the board that would match up with these slots.  If the contacts were there, it might be possible to convert the meter to accept type-K thermocouples directly. 

The meter does come with one type-K, but it is custom to this meter and has a non-replaceable probe.  Allowing the meter to accept generic K-type probes directly would be a bonus.  I doubt the contacts are there, though, and there is also the possibility that even if they were, they wouldn't work.

The meter has a dedicated, yellow "RS232" logging button on the front.  Since the logging is, to my mind, one of the better features of this unit, the inclusion of an explicit button for this feature is a nice touch.

On the downside, the logging cable provided is an old-fashioned DB-9 serial connector.  The 8218 DMM came with a USB cable, not a DB-9.  To use the 8226 cables, you will need either a very old PC or RS-232 to USB adapters of some kind. 

This is an annoyance that could have been easily avoided by supplying the 8218-style cable with the 8226.  I will have to test my 8128 cable with the 8226 to see if it works or not.  If so, I'll want some more 8218 cables, which may be hard to get, or I'll need 232-to-USB adapters, which are hit-and-miss in operation. 

The unit does come with full retail packaging (mostly in Chinese) and a complete paper Chinese/English manual.  Nice looking/feeling leads, a single type-K thermocouple and a 9V battery are also included.

Also supplied is a CD-R (not a CD) with "DRIVER" that presumably has the datalogging software. No indications if the software will support multiple meters or multiple instances running on different ports.  I hope so, since having 2-4 meters running on 1 laptop would be much better than a 1:1 laptop-to-DMM ratio.

I did notice that there seems to be a discrepancy between the box (600V Cat III / 1000V Cat II) and the meter (1000V Cat III), if that matters to anyone.

The LCD is big and easy to read.  Hopefully I can get them logging - I'm sure I have some 232-to-USB converters around here somewhere....

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