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DMM suggestions?

post #1 of 19
Thread Starter 
I'm looking to buy a DMM, in the $200 or less range. Suggestions? A local electronics shop carries the MeterMan brand, they had something for $130 that had inductance and capacitance, but lacked temperature. What's the verdict on Fluke equipment? Is it so much better to warrant the price? I might be persuaded to go a bit over $200, but would prefer not to...

-Jason
post #2 of 19
Yes, Fluke is well worth the money, in extra accuracy and durability. Have you looked on Ebay? Fluke 87III's go for about $100 used.
IMHO, Meterman makes out and out junk. The specs look good on paper, but not when you do the math to see what the real uncertainty of the measurements you are taking. Plus they are quite fragile. Also, they don't even calibrate them @ the factory, they just state the specs in such a way that they are sure to pass.
This isn't just idle speculation, I'm an electronics metrologist. I'll be happy to answer any questions about the measurement of electrical parameters.
post #3 of 19
Thread Starter 
How does the 87 III compare to the newer 170 & 180 series?

-Jason
post #4 of 19
Quite favorably. It is a better instrument than any of the 170 series meters, in that the 170's tend to integrate (ie, display the measurement ) quite slowly. In fact, the 179 was involved in a recall because it displayed AC measurements so slowly. It also tends to perform better, and has better specs.
Now, the 180 series is a horse of quite a different color. The 189 has performance rivalling that of many older benchtop DMM's. (this model used to be called the 89IV if you are looking @ used stuff). It is also VERY rugged. It's also ~$400 new. <shrug> Ya get what ya pay for. If HAD to choose, I'd buy a 189. But, and 87III for $100 is hard to pass up. I have about 50 of them at work, and they are reliable, accurate machines. They tend to perform well inside their specifications.
The really interesting part is, that although the new machines have better specs, they tend to drift more, and perform barely whithin specs.
Also remember, if you wanna match resistors, these machines ain't gonna cut it. Measuring resistance with a handheld is like kissing your sister, pleasing only in an abstract sort of way that isn't liable to get you anywhere..... For that, you need a machine that is capable of 4 wire measurements (for resistance @ DC) or an LCR (for resistance @ AC)
post #5 of 19
Could you explain what 4 wire measurements are?
post #6 of 19
Thread Starter 
Well, that's bad news! Can you explain further why the Fluke handhelds aren't good for matching resistors? I certainly don't know enough about the subject, as from looking at their specs and seeing that they measure resistance within 0.05%, I thought they would work just fine.

Can you recommend a good, reasonably priced LCR?

Also, I'm not opposed to getting bench meter, instead of a handheld. Would I get more for my money in a bench meter, as opposed to the Fluke 87 III/IV or 180 series? If so, what would you recommend for a good bench meter (new -or- used)?

Thanks!

-Jason
post #7 of 19
If you want high end features at a lower price than Fluke, check out the Protek 608 or Protek 506.
post #8 of 19
Thread Starter 
4-wire resistance measurement:
http://www.allaboutcircuits.com/vol_1/chpt_8/9.html

-Jason
post #9 of 19
Circuit Specialists in Arizona has many DMMs (Fluke, Wavetek, Protek). The DMMs at "World Beater Prices" are made in China. These are good, affordable DMMs for those that can't afford a Fluke. Take a look...

http://www.web-tronics.com/test-equipment.html
post #10 of 19
Quote:
Fluke is well worth the money, in extra accuracy and durability.
Also consider warranty and repairability. If you buy a $200 meter from a company that has no repair facilities, are you better off than if you'd spent $400 on one that can be repaired?

Quote:
Meterman makes out and out junk.
One positive things about Meterman is that they are now owned by Fluke, so Fluke can repair and calibrate them.

If you want something between these two, there's Wavetek, which is also owned by Fluke. If you are looking on the used market, Beckman made good stuff...and guess what, they are also owned by Fluke, by way of Wavetek, I think.

Quote:
Could you explain what 4 wire measurements are?
The short version is, in a two wire measurement (i.e. a normal DMM) there is resistance in the measurement wires, and therefore a voltage drop which interferes with the accuracy of the meter. This matters most at low ohmic values.

With a 4-wire system, you run two wires to each side of the resistance to be measured. Two wires provide a constant current across the resistance, and the other two measure the resulting voltage drop across the resistance. Since the measurement wires go back to a high impedance input, the resistance in the measurement wires is irrelevant. It gives much more accurate readings, especially at low values.

Quote:
Can you recommend a good, reasonably priced LCR?
It won't fool you into believing you'd bought a Fluke, but I like the kit from Almost-All Digital Electronics. It has a build quality between that of a typical DIY project and a good quality commercial meter. I've casually compared it to a B+K Precision 878 we have at work, and it seems to compare favorably; not bad for $100, vs. the $275 you'll pay for the B+K. The AADE meter doesn't have 'R', but my Fluke fills that role well enough. The Fluke also has capacitance metering, but the AADE clearly outclasses it.

If you want Fluke-like build quality and can stand the price, the B+K is a good buy. I seem to recall that they have a somewhat cheaper model as well.

Quote:
The DMMs at "World Beater Prices" are made in China. These are good, affordable DMMs for those that can't afford a Fluke.
I don't know about their other meters, but the one they give away with your order if you buy enough stuff is worth exactly what I paid for it. I've got two. One came in with the dial tilted, so I opened it up to fix it, thinking that I'd find a bent shaft. No indeed...I found that the whole mechanism had basically fallen apart inside. I put it back together, and it turns well enough now, but I know it'll fall apart again. Not a good sign.

While I was inside the meter, the circuitry I saw didn't inspire confidence. I can't recall details, but it was clearly built with the lowest possible price foremost in mind.

For a freebie, hey, what the heck. Get one to use on risky measurements where you might blow the meter up. Use it where you need two meters, one to keep an eye on something that isn't critical while you measure something that is critical with your good meter. Put it in the car for emergency use. Use it as a paperweight. Whatever, it's okay for all that.
post #11 of 19
Thread Starter 
Well, I ended up picking up a used HP 3468B benchtop DMM from eBay, for $167.50: http://cgi.ebay.com/ws/eBayISAPI.dll...em=2583919421.

This one can do 4-wire resistor measurements, to satisfy my inner perfectionist.

bigcat39 suggested Pomona-brand leads from Newark. Anyone else have other suggestions for leads? Not that the Pomona ones won't work, in fact I haven't even had time to check out leads and prices yet, just looking to see if anyone else out there had suggestions.

I also picked up a used B&K Precision 875A LCR meter from eBay for $63.50. Completely unnecessary, I know! But then again, it's to satisfy that evil inner perfectionist.

I'm sure I'll have fun with both of them and my PPA!

Comments/suggestions/condemnations welcome...

-Jason
post #12 of 19
Quote:
Anyone else have other suggestions for leads?
Pomona is good. In fact, you probably won't be able to find any other "name" brand. I have a bunch of their Minigrabber jumpers and some BNC to Minigrabbers. Good stuff.

Quote:
Comments/suggestions/condemnations welcome...
Get 'em calibrated. You don't know where they've been....
post #13 of 19
Thread Starter 
Tangent:

Thanks for the reply! I think the hardest thing is knowing what to get. I downloaded the Pomona catalog last night, and there's so many P/Ns it made my head spin. I think I might just end up going with one of their DMM "kits" + some Kelvin clips.

BTW, why are Kelvin clips so darn expensive?

And already arranged to get them calibrated, I agree, don't know where they've been.

-Jason
post #14 of 19
On the "World Beater Prices" DMMs...

Tangent: I agree with your opinion on the cheap DMMs. So I suggest that you stick with DDMs that cost more than $35. That said, I feel the pricier ones work very well.

My friend Chris has a Master's in EE and 30+years experience fixing amps. He checked out my CSI-345 against a Fluke, and he liked it enough to order one. The MAS-345 sells for $40. It comes with a PC link/software to record readings, a feature Chris loves! Take a look...

http://www.web-tronics.com/indmmwrspcin.html

Oh, one of these days, I will get a real nice Fluke. Right now, though, the CSI-345 does the job perfectly!
post #15 of 19
Quote:
the hardest thing is knowing what to get
I know you want to match some resistors, so consider getting something that can grab a resistor by its lead and hold it securely. Not all grabbing type probes will do this well, due to their design. If you don't do it this way, you have to hold two probes and a resistor in two hands, and keep it all steady while you read the value off the meter. It's not the most difficult thing, but it is less than desirable; you end up bending the resistor leads while you hold it securely against the probes this way, as well. With good grabbers, the resistor leads stay straight and you only have to hold the probes.

You'll also want a grabbing probe with a bigger jaw than will work for resistor matching. Use this for clamping one probe to ground while you poke with a standard probe elsewhere, for instance.

The flexible grabbers can sometimes be helpful, for holding a probe to a hard-to-get-to test pin. This one is definitely not a high priority item, though.

While you're shopping for probes, get some DMM fuses. Nothing worse than blowing the ammeter side's fuse through a slip of the probe to a high-current section of the circuit, and then having to wait a week for a replacement fuse to arrive. You won't find 'em in the fuse section of Home Depot.

Quote:
I downloaded the Pomona catalog last night
You'd be better off starting with the catalog of one of the distributors and picking parts that way. I don't know that any of the distributors carry the entire Pomona line. It's possible of course, I just mean that I would choose the distributor first, simply because I'd probably want to order something else at the same time.

Quote:
why are Kelvin clips so darn expensive?
A) Low sales volume

B) They're only used with high-dollar equipment. The manufacturers figure you can afford it if you can buy such a high-end instrument that it can use Kelvin probes, and you should only use high-quality probes with high-end instruments anyway.
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