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Meter accuracy

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torch:
I am currently refurbishing my tube tester (a Tripplet 3444). One important step is to set the line voltage measurement and the manual specifies that the meter used to do this must have an AC accuracy of 1/2% or better. My 'good' meter (a Goldstar 334, which was a $200 meter 20 years ago) has a claimed AC voltage accuracy of 1% -- when it was new. So maybe it's time to buy a new meter. I've looked at the claimed accuracy of some of the units in Dave's $100 meter shootout, the best seems to be 0.8% -- close but no cigar.

This Tripplet is almost as old as me; how much meter do I have to buy to get 1960s era accuracy? Is there a simple and reliable way to check the accuracy of my meter that doesn't involve using the same meter to measure the value of a resistor & current?

EEVblog:
Now you get into the murky subject of True RMS.
On most True RMS meters, 0.5% AC accuracy would be very good indeed.
Even the Fluke 87V is only 0.7% with True RMS.
But the kicker is the cheaper non-true rms average responding Fluke 83V is 0.5% because it's easier to get better accuracy when you don't use a True RMS converter chip.
So if you know your signal is precisely a sine wave, then an averaging responding meter will give you better accuracy/$ here.

Dave.

Simon:
essentially to calibrate a measuring instrument you need a reference that is at least an order of magnitude if not two better than the one being calibrated - just a fact of measuring life  ;D

torch:

--- Quote from: EEVblog on May 30, 2011, 12:49:10 pm ---But the kicker is the cheaper non-true rms average responding Fluke 83V is 0.5% because it's easier to get better accuracy when you don't use a True RMS converter chip.
--- End quote ---

Ok, now that surprises the #&!! out of me.  :o


--- Quote from: Simon on May 30, 2011, 02:12:42 pm ---essentially to calibrate a measuring instrument you need a reference that is at least an order of magnitude if not two better than the one being calibrated - just a fact of measuring life
--- End quote ---

That doesn't.  :(   (it's the same in machining -- if you need to hold a 1/2 thou tolerance, you need a mike that's accurate to a tenth.)  Oh well, maybe I'll just use the $15 el cheapo I carry in the car -- if cheaper is better, that one should be bang on!  :D

Simon:

--- Quote from: torch on May 30, 2011, 08:23:35 pm --- (it's the same in machining -- if you need to hold a 1/2 thou tolerance, you need a mike that's accurate to a tenth.) 

--- End quote ---

Yes I'm a quality inspector for a so called engineering company although they have no given me formal training so I go mostly by intuition (better that some peoples theories  ::))

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