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Mastech MS5308 LCR meter with ESR measurement - on discount at the moment
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LaurenceW:
Electrician and AMspire, those are interesting discussions, and it is useful to see the behaviour of a component across a swept range of frequencies, rather than spot values. I guess I knew that the a component's apparent values must shift with frequency, but I hadn't thought about the degree. Heck, it amazes me that half of this stuff works at anything faster than DC!
Fraser:
I agree with the comments made in the review by LaurenceW but think it worth making some additional comment.

The case is LARGE but that is clear from the units specification so should not be a surprise. Unlike the Unit-T bench multimeters that are a bit like a sandwhich box with a single PCB behind the front panel, I do feel that the MS5308 is appropriate as a bench meter. It is portable if needed but it makes a very clear and stable bench meter. I have the Wayne Kerr 4210 and that is a true monster in comparison, as are the likes of Racal and other bench LCR meters. Mastech already sell several handheld LCR meters and this unit apppears to be a bit of a 'statement piece' with the size and unusual 'Tektronix like' case supposed to infer professional quality  ?

As the unit uses a known generic chipset and the PCB is, IMHO, of acceptable quality to maintain the chipsets specified accuracy, it is really a case of buying the Cyrustek based LCR meter that meets the size and cost specification of the user. I agree that prices may drop but LCR meters are not as common as multimeters so that may always have an effect on price (though UNI-T seem to have made this a myth with their cheap LCR meters).

When comparing the MS5308 to other LCR meters, it is well worth considering what is supplied with the meter. In the 'large' carry bag you get the MS5308, batteries, interface lead, software, PSU, Tweezer adapter, Kelvin Clips adapter and the bag itself  :)  Some other competitors appear to charge extra for the accessories which can up the price considerably. The MS5308 hits the ground running and is a complete package upon arrival.

In my specific case, the size is a benefit and I am not unhappy with the design or the plastics used. This is not a flimsy unit and I am thankful that it has not been covered in that awful thin rubberised layer found on some equipment.....such rubberisation can go sticky with time and use. A rubber boot around the case would have been great but is not essential in my scenario. It is not a significantly inferior case to my Tektronix THS-720 DSO which is also of hard plastic but durable.

With regard to the batteries required. LCR meters are power hungry and I am pleased that Mastech give the option of a PSU or AA batteries. As Dave has stated, AA battery capacity is far preferable to that of small PP3 batteries. The 9V battery slot is interesting. I seem to recall that another LCR meter used AA plus PP3 batteries for some reason (not known by me) Mastech have gone the correct route and taken all required supplies from one battery pack.

To summarise......... Yes its large, Yes its Plastic, Yes it takes a lot of batteries......BUT it does what it says on the tin, Yes it comes with lots of accessories and Yes it appears robust. It is like Marmite, you either love the design or hate it  ;D

The price was certainly good value for money as well, and it came from a UK warehouse in double quick time  :D

I would think any half decent LCR meter using the Cyrustek chipset will be good unless the manufacturer messes up the PCB design. My advice is.....Pick the design and price that most suits your needs. THEN download the DE5000 manual as has been stated  ;)

Aurora
amspire:

--- Quote from: Aurora on April 28, 2012, 10:58:48 am ---With regard to the batteries required. LCR meters are power hungry and I am pleased that Mastech give the option of a PSU or AA batteries. As Dave has stated, AA battery capacity is far preferable to that of small PP3 batteries. The 9V battery slot is interesting. I seem to recall that another LCR meter used AA plus PP3 batteries for some reason (not known by me) Mastech have gone the correct route and taken all required supplies from one battery pack.

--- End quote ---
My guess is they had to leave the option open to go back to a 9V battery. Either they  had a switching converter, and they were not sure if it could cause interference, of they were not sure if they could get the performance required without extra voltage to part of the circuit. I think this must happen a bit, as I have seen multimeter cases with "9V" molded into the plastic as the operating voltage, but inside they run of two AAA batteries.

Richard.
amspire:

--- Quote from: LaurenceW on April 28, 2012, 10:19:08 am ---Electrician and AMspire, those are interesting discussions, and it is useful to see the behaviour of a component across a swept range of frequencies, rather than spot values. I guess I knew that the a component's apparent values must shift with frequency, but I hadn't thought about the degree. Heck, it amazes me that half of this stuff works at anything faster than DC!

--- End quote ---
The Electrician is choosing the type of capacitors that will have variations, and they are not the capacitors you would pick if you needed accuracy at 10MHz.

The performance of something like a 100pF NPO SMD capacitor is good over a much wider range.

If you think capacitors are bad, you better not start testing inductors.

If it makes you feel any better about capacitance, until the Quantum Hall Effect resistance standards came along, the resistance standard were calibrated using a special quadrature bridge from a primary standard capacitor - a 0.5pF calculable capacitor. Last I heard, someone had reached 18 digits of resolution in measuring it. The measurement frequency is usually 1KHz, the dielectric is a vacuum, and the test voltage is probably in the hundreds of volts at least - perhaps thousands of volts.

The best capacitors we can make are many orders of magnitude more accurate and stable then any non-Quantum Hall effect resistor, but you would not know it from the parts we have to use everyday.

Richard.
The Electrician:
I chose the capacitors to be responsive to the question:


--- Quote from: LaurenceW on April 27, 2012, 11:19:32 pm ---One surprise is the widely differing capacitance readings given for the same device at different frequencies. Which is correct? I need to read up on that!

--- End quote ---

Even the lowest cost LCR meters usually measure at 100 Hz, 120 Hz and 1 kHz, and you won't usually see much difference in the readings at those frequencies, but the meters that also measure at 100 kHz may see differences even for perfectly good capacitors.  My purpose was to explain why non-defective capacitors can give different readings at different frequencies.

Ths slow-ion-movement-in-etched-pores effect is, AFAIK, limited to electrolytics.  The series resonance effect is going to be noticed at 100 kHz only with large valued capacitors.  As you say, small valued capacitors such as 100 pF caps, won't show these effects at 100 kHz.

These effects take place even if the capacitor is not defective, and the user of a 100 kHz capable LCR meter should keep them in mind.  The different readings don't necessarily mean that the capacitor is bad.

I hope LaurenceW hasn't gotten the impression that capacitors are bad; they just have limitations one should be aware of.

As my plots show, not all electrolytic capacitors exhibit the slow ion effect; an LCR meter can help detect which ones do.

Here are plots of a couple of capacitors from my collection.  They are identical older Mallory capacitors with an epoxy seal rather than the currently more common rubber seal.  They are rated 50 uF at 50 volts.  There are no signs of swelling or leakage around the epoxy seal, yet something is wrong with one of them.  The good one, Mallory1, has a capacitance of 66.8 uF at 1 kHz and a respectable ESR of .308 ohms.  The bad one, Mallory2, has a capacitance of 8 uF at 1 kHz and an ESR of 82 ohms!

The images show the sweeps of the caps individually and superimposed.
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