Equipment Review

MASTECH® Model MS8050A Bench Top Digital Multimeter.

I have been messing around with bargain priced DMMs for many years. "Even a poor DMM", I rationalized, "is at least as accurate and probably more so than an analog meter". So, I finally decided to spend the money and get a really good DMM. In these times it is impossible to avoid things that are made in China. I selected a dealer that provides a state side guarantee. Something over a year ago I bought this expensive benchtop DMM but I do not use it for day to day measurements. I want to save it as a comparison standard for checking the calibration of lesser DMMs.

8050 reading the line voltage and frequency on my bench.

As you can see it has the usual functions plus a few that aren't readily apparent. "When all else fails, read the instruction manual". The manual for this meter is written in understandable English. I would describe it as slightly damaged rather than broken. The syntax will occasionally bring on a smile but the meaning remains clear.

DMMs Count.

You are probably accustomed to, the defacto standard and totally misnamed, 3-1/2 digit DMM. Someone in years past, probably from the marketing department, thought that adding a digit on the left side of a 3 digit display was equivalent to adding half a digit. Adding a complete 4th digit would increase the range by a factor of 10. A half digit increase should extend the range by a factor of 5. Or some might say 3.16. A factor of 2 is a long way from being half a digit.

These displays will count to 2000. But, I hear you saying, the display only goes up to 1999. Correct but you are forgetting to count the zero state. Consider the single digit case. Count on your fingers, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9. Counts are important because that is how DMMs are now being specified to avoid the ridiculous fractional digit claims.

This meter is advertised as a 53000 count meter. The auto ranging system upshifts when the count reaches 52999 counts which makes it a true 53000 count meter. It downshifts when the count becomes 50000. That prevents the range from jumping back and forth making the display value impossible to read.


This meter measures: Additional features are;

DC Voltage, AC Voltage, or DC + AC voltage Ranges;

DC Current, AC Current, or DC + AC Current Ranges; Resistance Ranges. Capacitance Ranges. Note: Manual override of Auto Ranging does not function in capacitance mode.
  • 0 to 50.00 nf,
  • 0 to 500.0 nf,
  • 0 to 5.000 µf,
  • 0 to 50.00 µf,
  • 0 to 500.0 µf,
  • and 0 to 5000 µf. Frequency Range. Sinewave input > 1/10 voltage or current range. 5 Hz to 200 kHz. Frequency Range. Logic level input 2 to 5 volts. 5 Hz to 2 MHz. Duty cycle range (logic level) 5 Hz to 500 kHz. 10% to 90%. Diode check: Indicates diode forward voltage drop at a current of approximately 0.7 mA.


    The basic DC volts accuracy is ±(0.03% + 6 counts*). * is 10 counts on 50 mV range.

    The AC volts accuracy is ±(0.5%* + 40 counts) * 40 Hz to 1 kHz. 1% 1 kHz to 10 kHz. 2.5 % 10 kHz to 20 kHz.

    Current accuracy is 0.75% with counts jumping between 10 and 20. 1% on 10 A range and worse at higher frequencies.

    Resistance accuracy is 0.1% jumping to .5% on 50 Meg range.

    Capacitance accuracy is 1% going up to 2% on two highest ranges.

    Frequency accuracy is ±(0.006% + 4 counts)

    Duty cycle accuracy is ±10%)

    Input Resistance.

    The specifications page of the manual is silent on the matter of input resistance. However some testing with another meter indicates that the input resistance in the DC volts and DC/AC mV modes is approximately 10 Meg ohms. The reading varied between 9.9 megs and 11 megs. On the AC range the DC input resistance showed "OL" indicating an input capacitor.
    The LCR meter indicated an Rp value of 10.7 Megs and a Cp value of 109 pf.

    AC to DC Converter.

    On the front panel of this instrument and in many places in the manual the letters RMS appear prominently. My results from comparing readings between RMS and non RMS meters was a bit surprising. The two meters agree within the accuracy of the meters when a sine wave is used. But when the wave is changed to a square wave the readings are only different by about 5 %. I expected more of a disparity. Nonetheless a 5% difference is enough to tell you if your true RMS meter is truly RMS.


    All in all I would say that I am very satisfied with this meter. The readings are stable and the display easy to read. The controls are intuitive enough that I was able to figure it out with only a few manual lookups. I would give it a rating of 5 stars and I highly recommend it.


    Dimensions 9 x 4 x 12-1/2" with bale handle removed.
    Weight 5 lb. 8.2 oz.
    Note: Converted from metric data in manual.

    Price US $279.00 from this location.
    At this writing a note on the page says "10 in stock." This meter has been around for a while and I imagine that when those 10 are gone it will go away. If you want one better get it while you can.

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