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Fluke 77-IV vs ExTech EX330 differences I noticed.

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blewisjr:
Yes I understand that these meters are in a totally different league.  The Fluke 77-IV appears to have all the same functions minus the No Contact Mains voltage detector.  The ExTech has mA, and uA but no mV and has temp where the fluke has mA but no uA but has mV and does not have temp.  Both have duty cycle, capacitance, continuity, Resistance, and diode.

The biggest thing I noticed with these two meters is the shear difference in accuracy.  For instance on a capacitance test of a 100nF capacitor the ExTech gives 76.3 and the Fluke gives 114 both set to nF.  The Fluke can also do uF and that comes up at 0.11 as expected.  That was just a quick test but I am surprised by how far off the ExTech was.

I do not know if it is important to have a uA setting but I am sure mA is good enough.  I also noticed the auto ranging on the Fluke is at least 10x as fast.

Anyone have any ideas on why the ExTech could be so far off on capacitance I still have to check the voltage accuracy differences and such on my power supply yet?

Any thoughts on this Fluke meter do you think it will be more then good enough for my uC projects?  I was able to nab this thing off ebay for $144 usd.
http://www.fluke.com/fluke/SGEN/Digital-Multimeters/Fluke-77-IV.htm?PID=56126

krivx:
You have two meters giving different measurements, possibly with different methods. How can you say if either meter, if any, is giving an inaccurate reading?

blewisjr:
I was using the same basic capacitor of known value on both meters and the one meter was way off the value.  So I would assume it is naturally giving a inaccurate value.

Lightages:
krivx is correct. You have no idea which is wrong. One is 14% out the other is 24%. You can only be sure if you have a known and measured value with a known accurate meter. To declare the Fluke correct without this is called "observer bias".

Now having aid that I would end to distrust any Extech EX series meter as they are built like shit.

PedroDaGr8:

--- Quote from: blewisjr on April 02, 2013, 01:51:15 pm ---I was using the same basic capacitor of known value on both meters and the one meter was way off the value.  So I would assume it is naturally giving a inaccurate value.

--- End quote ---

First off, capacitor values are typically +/- 20%. This means that the capacitor could be considered 80-120uF, when you factor in that most capacitor readers are typically 4% or so in accuracy the reading could be 76.8-124.8 and still be considered a correct reading. This doesn't even take into account the fact that capacitance varies with frequency and there are a variety of methods for testing capacitance (some use a known frequency and test the attenuation of the signal in a filter, other charge a capacitor for a known length of time and test the resulting voltage). This is why you can get some widely varying but equally accurate results (not saying the Extech is accurate, just that it COULD be)

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