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Mastech MS5308 LCR meter with ESR measurement - on discount at the moment
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The Electrician:
There has been at least one thread on the forum that asks whether it's worth getting an LCR meter with 100 kHz capability.  In the past this has cost a substantial increment in price, but recently the price increment isn't so large.

Here's a nifty thing you can do with a meter having a 100 kHz measurement capability.

I've attached an image showing a sweep of the impedance at one end of a 100 foot roll of telephone twisted pair cable.  This is the old stuff, not modern Cat5 cable.  The image show two sweeps superimposed; one with the other end of the cable open circuited and one with the other end of the cable short circuited.  The impedance where the two curves cross is the characteristic impedance of the cable.  Marker B is set at one of those crossings; the frequency is 2.5255 MHz and the impedance is 112.686.  This kind of cable is usually said to have a characteristic impedance of about 100 ohms; the measurement confirms this.

An LCR meter that can measure Z and phase angle (theta) can be used to determine the characteristic impedance of a cable.  A measurement frequency of greater than 100 kHz would be better, but 100 kHz can do a fairly good job.  You will need a substantial length of the cable, 100 feet or more.

Connect the meter to one end of the cable with the other end open circuited.  Measure the impedance at 100 kHz; I got 1166<-89.6 (this is 1166 ohms at a phase angle of -89.6 degrees).  Now short circuit the other end of the cable and measure the impedance again; I got 13.42<64.87.

Multiply the ohms readings: 1166 * 13.42 = 15647.72.  Take the square root of this: SQRT(15647.72) = 125.09; this is the characteristic impedance.  This compares favorably with the value of 112.686 obtained from the sweep in the image.  For a check, add the two phase angles: -89.6 + 64.87 = -24.73; divide by 2 and get -12.365.  This is the phase angle of the impedance; ideally it should be zero, if it's small, the value for the impedance is likely to be close to the correct value.

If you try this same procedure at 10 kHz, you will get a not so good result, so this is why 100 kHz capability is a good thing.
zoltm:
Hi Electrician,

You description below gets me curious, if the 100K capable LCR meter could indeed help to measure the effective impedance on an audio loudspeaker?

Thanks.
 

--- Quote from: The Electrician on April 28, 2012, 10:41:15 pm ---There has been at least one thread on the forum that asks whether it's worth getting an LCR meter with 100 kHz capability.  In the past this has cost a substantial increment in price, but recently the price increment isn't so large.

Here's a nifty thing you can do with a meter having a 100 kHz measurement capability.

I've attached an image showing a sweep of the impedance at one end of a 100 foot roll of telephone twisted pair cable.  This is the old stuff, not modern Cat5 cable.  The image show two sweeps superimposed; one with the other end of the cable open circuited and one with the other end of the cable short circuited.  The impedance where the two curves cross is the characteristic impedance of the cable.  Marker B is set at one of those crossings; the frequency is 2.5255 MHz and the impedance is 112.686.  This kind of cable is usually said to have a characteristic impedance of about 100 ohms; the measurement confirms this.

An LCR meter that can measure Z and phase angle (theta) can be used to determine the characteristic impedance of a cable.  A measurement frequency of greater than 100 kHz would be better, but 100 kHz can do a fairly good job.  You will need a substantial length of the cable, 100 feet or more.

Connect the meter to one end of the cable with the other end open circuited.  Measure the impedance at 100 kHz; I got 1166<-89.6 (this is 1166 ohms at a phase angle of -89.6 degrees).  Now short circuit the other end of the cable and measure the impedance again; I got 13.42<64.87.

Multiply the ohms readings: 1166 * 13.42 = 15647.72.  Take the square root of this: SQRT(15647.72) = 125.09; this is the characteristic impedance.  This compares favorably with the value of 112.686 obtained from the sweep in the image.  For a check, add the two phase angles: -89.6 + 64.87 = -24.73; divide by 2 and get -12.365.  This is the phase angle of the impedance; ideally it should be zero, if it's small, the value for the impedance is likely to be close to the correct value.

If you try this same procedure at 10 kHz, you will get a not so good result, so this is why 100 kHz capability is a good thing.

--- End quote ---
Lo_tse:

--- Quote from: Aurora on April 28, 2012, 10:58:48 am ---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

--- End quote ---


I totally agree with Aurora. I bought one after reading his earlier review and after quite a bit of research on the internet.  Particularly some of the comments on the Chinese DIY forum Crystalsradio (in Chinese).  It was on Crystalsradio that someone commented on the "spacious interior" of the meter.  One of the poster did a quick comparison of the Mastech meter with a certain model of Agilent bench LCR meter and was quite happy about the accuracy. 

I am not a big fan of the plastic shell but it seems sturdy enoug.  The meter comes with all the accessaries that I wanted and more (the data cable) and I only paid 150 US$ for it (plus 55$ for shipping).  The only unknown at this point is the longevity of the meter and only time will tell.  For DIY use, I think this meter is way more than adequate. 

Lastly, I would like to thank Aurora again for informing me about the manual of the IET 5000 - night and day as compare to the one that comes with the meter.  Mastech should be ashame. 

Regards,

Lo_tse
The Electrician:

--- Quote from: zoltm on April 29, 2012, 03:47:37 pm ---Hi Electrician,

You description below gets me curious, if the 100K capable LCR meter could indeed help to measure the effective impedance on an audio loudspeaker?

Thanks.
 

--- Quote from: The Electrician on April 28, 2012, 10:41:15 pm ---There has been at least one thread on the forum that asks whether it's worth getting an LCR meter with 100 kHz capability.  In the past this has cost a substantial increment in price, but recently the price increment isn't so large.

Here's a nifty thing you can do with a meter having a 100 kHz measurement capability.

I've attached an image showing a sweep of the impedance at one end of a 100 foot roll of telephone twisted pair cable.  This is the old stuff, not modern Cat5 cable.  The image show two sweeps superimposed; one with the other end of the cable open circuited and one with the other end of the cable short circuited.  The impedance where the two curves cross is the characteristic impedance of the cable.  Marker B is set at one of those crossings; the frequency is 2.5255 MHz and the impedance is 112.686.  This kind of cable is usually said to have a characteristic impedance of about 100 ohms; the measurement confirms this.

An LCR meter that can measure Z and phase angle (theta) can be used to determine the characteristic impedance of a cable.  A measurement frequency of greater than 100 kHz would be better, but 100 kHz can do a fairly good job.  You will need a substantial length of the cable, 100 feet or more.

Connect the meter to one end of the cable with the other end open circuited.  Measure the impedance at 100 kHz; I got 1166<-89.6 (this is 1166 ohms at a phase angle of -89.6 degrees).  Now short circuit the other end of the cable and measure the impedance again; I got 13.42<64.87.

Multiply the ohms readings: 1166 * 13.42 = 15647.72.  Take the square root of this: SQRT(15647.72) = 125.09; this is the characteristic impedance.  This compares favorably with the value of 112.686 obtained from the sweep in the image.  For a check, add the two phase angles: -89.6 + 64.87 = -24.73; divide by 2 and get -12.365.  This is the phase angle of the impedance; ideally it should be zero, if it's small, the value for the impedance is likely to be close to the correct value.

If you try this same procedure at 10 kHz, you will get a not so good result, so this is why 100 kHz capability is a good thing.

--- End quote ---

--- End quote ---

Any LCR (or LCZ) meter can be used to measure a speaker impedance; you only have to connect the speaker to the meter.  The impedance is, of course, only measured at one of the test frequencies used by the meter.

It appears to me that the MS5308 doesn't have a z/theta mode.  For a meter that doesn't have such a mode, you will have to derive the impedance from a measurement of Ls and Q or Cs and D.
LaurenceW:
Well no, I don't necessarily think capacitors are bad. Despots, Hyper-inflation, droughts, anything by Boney-M; they're BAD. Capacitors are just capacitors. (mainly). Clearly, not all caps are created equal.

It is interesting and educational to me to see how different capacitors perform and measure at different frequencies.  I learn that Polystyrene caps are pretty damn good, and give consistent high quality readings. I learn that electrolyics basic values don't vary  as much as the often quoted -20/+80% tolerances would lead you to believe.

 I wasn't expecting to see even quite small electrolytics drop off in indicated value at higher frequencies, so rapidly. I guess that's other parameters in the component coming into play (and maybe explains why you'll often see a small ceramic cap straight across a larger electrolytic one)

I am not complaining about more batteries - (8 AA's) over a smaller 9V pack. The larger solution will last MUCH longer and be cheaper too.

The size is of the MS5308 is what the size is, and yes, it's probably even written down in the spec, somewhere. Did I read that? NAH! But there is no doubt that this instrument is larger than it needs to be.  It packs a lot of fresh air. "Pocket" it is not!

My experience to date of the PC software is that it is C R A P. Actually, I cannot get it to work, but even if it ever does, I don't think I've got a use for it. It looks to be poorly written, and is VERY basic. Data doesn't even fit in the (fixed size) windows. The software doesn't even appear to capture all of the parameters that the meter is capable of measuring. But this is not why I bought the instrument.

Still happy on balance with my purchase, though.
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