[KT88]

Hi Guys,

After going through a bunch of DMM's (the current going for about 60$ or so) I've decided I now have the need for a better unit which will be accurate, reliable, and will meet my needs in the next few years. I dont minding paying more, just need something that will justify it (just like I've bought the Hakko FX951 which isn't cheap but just better than anything I've had/used). I am not looking to spend as much as possible though, so if a 100$ Fluke 115 is almost the same as the more expensive units I would have it instead of spending much more.

My main focus is the Fluke DMM's since a few of my friends have recommended these.
However, I can't really understand the different series's Fluke has, and locate the exact differences between them. I would appreciate some help.

My needs are basically quite usual, capacitance, resistance, DC (A,V), AC (A,V), diode test, and if possible frequency as well. I would like it to be auto-ranging.

Thanks.

 

[DaMnEd]

The higher you go on Fluke's DMM range, the more accuracy/resolution you get, this is the main difference, and you get other goodies like bigger screens (to accommodate the accuracy you get, you usually need more numbers ), new reading capabilities like frequency readings, LoZ, bigger ranges for resistance, a 115 tops at 6MΩ, a 289 tops at 500MΩ... Capacitance on the 115 tops at 1000 µF, 289 tops at 100mF, that is 100K uF's.., logging, TrendCapture etc.

Why you may "need" or find useful to have a more accurate DMM when building amps/Dacs,etc? Read this: Hand-Matching Resistors to Tighter Tolerances

It is really up you to balance the things you could use (or not use) against the cost, you can find good deals on used/new Flukes on ebay.

Ah, with some DMMs (the top ones) you get lifetime warranty (that is 10 Years after the particular model is discontinued if I'm not mistaken), just be sure to read the conditions on Flukes website (they only warrant the DMMs of you are the first owner and buy from a reputable/official dealer).

 

[KT88]

Hi,

Thank you for the information.
How big is the difference in accuracy? From what I see even the cheaper models are about the same.

What about the 17X line? I've heard hey had some problems with the sleep mode, are these problems fixed in the models sold now?

BTW, I will be needing it for other thing than amps and DAC's (for these the one I have is more than enough), I'm gonna need it for some projects (EE student), plus, its always fun to have a good tool

 

[DaMnEd]

Quote:

Originally Posted by KT88 /img/forum/go_quote.gif Hi, Thank you for the information. How big is the difference in accuracy? From what I see even the cheaper models are about the same. What about the 17X line? I've heard hey had some problems with the sleep mode, are these problems fixed in the models sold now? BTW, I will be needing it for other thing than amps and DAC's (for these the one I have is more than enough), I'm gonna need it for some projects (EE student), plus, its always fun to have a good tool

You only start to get substantial resolution differences from the 8x series (87V) (20K count) up, like the 187/187(discontinued, 50K count), 287/287 (50K count).

If you read tangents article I posted he explains this in great detail.

(The focus is resistance but the same applies to other measurements).

 

[KT88]

Thanks, I've read it.

The only question that remains is what will happen to it in say 2 years? How accurate will it be than? What needs to be done to calibrate it?

 

[DaMnEd]

The article also explains that, look up "Drift"

.

The only way to be sure how accurate it would be after 2 years is to send it off to be calibrated, and ask how accurate it was at the time, before calibration.

The only numbers we have are that the accuracy is specified for a period of one year after calibration. Many companies send the DMMs every year (or less) to be calibrated, specially the ones that really do need to be sure they are getting accurate results on the field.

For personal use I'd say ship it to Fluke for calibration every 2/3 years.

 

[KT88]

Thanks, that's exactly what I wanted to know.
Any idea how much it'll cost to get a DMM calibrated?

 

[tangent]

Calibration for a hand-held meter is around $50. It is optional. If your main goal in getting a better meter is superior build quality -- better feel, more accessories, more durable -- there isn't much reason to recalibrate it. Periodic calibration is necessary if you're expecting the meter's readings to live up to the accuracy claimed by the manufacturer.