Help with Fluke 116 uA troubleshoot

[smoothtalker]

I've a Voltagestandard DMMCheck Plus with 500uA output. It's calibrated to 500uA and about 480mV when I measured it.

But the fluke116 is not reading correctly. It's reads 158uA. Interestingly I've asked fluke about the burden voltage of fluke 116 and its 1.55V at 500uA so that's about 3mV per uA

Does anyone knows what is wrong with my fluke116?

[alm]

If the open circuit voltage of the DMMCheck Plus is 480 mV, then the compliance of the current source is probably too low for the high burden voltage of the Fluke 116.

[smoothtalker]

If the open circuit voltage of the DMMCheck Plus is 480 mV, then the compliance of the current source is probably too low for the high burden voltage of the Fluke 116.

Hmm.. But I've also asked Doug and he mentioned that the 1.55V should not be a problem. He reckon its my meter that is the culprit

[alm]

So what's that 480 mV figure you mentioned?

[smoothtalker]

So what's that 480 mV figure you mentioned?

It's the voltage across the 500uA terminals. I've put a 10k resistor and it reads the same too. Doug confirms the voltage is correct

[alm]

So if it can only go up to 480 mV, even without a load, how is it going to overcome a 1.5 V burden voltage? The Fluke 116 will have a shunt resistance of 3.1 kohm (1.55 V / 500 uA). 480 mV across 3.1 kohm results in 155 uA, pretty close to 158 uA.

My guess is that either the 480 mV open circuit voltage is wrong, Doug misunderstood the Fluke 116 burden voltage spec or was confused about Ohm's law when he answered your question.

[smoothtalker]

So if it can only go up to 480 mV, even without a load, how is it going to overcome a 1.5 V burden voltage? The Fluke 116 will have a shunt resistance of 3.1 kohm (1.55 V / 500 uA). 480 mV across 3.1 kohm results in 155 uA, pretty close to 158 uA.

My guess is that either the 480 mV open circuit voltage is wrong, Doug misunderstood the Fluke 116 burden voltage spec or was confused about Ohm's law when he answered your question.

I had the same opinion as you. That's why I verified with Doug.

Hmmm.. how should we conclude this incident? Is this an issue with the multimeter because the burden voltage is too high? Or could the dmmcheck plus be improve? Haha..

[alm]

The burden voltage of the 116 is unusually high (not really intended for electronics use), so I wouldn't really blame this on the DMMCheck. The Fluke 87V would only have 50 mV burden voltage, for example. It wouldn't surprise me if Doug checked the specs for a bunch of DMMs and all were under 480 mV. It might be nice to state the compliance voltage of the DMMCheck Plus on his website, though.

[smoothtalker]

It might be nice to state the compliance voltage of the DMMCheck Plus on his website, though.

Yea. That's a good idea..

[dr_p]

Did you remove uA meter when you measured the 480mV?    I mean, was it really open-circuit voltage? No LoZ obviously

[smoothtalker]

Did you remove uA meter when you measured the 480mV?    I mean, was it really open-circuit voltage? No LoZ obviously

Oh. I used the 116 to measure the voltage. Doug also confirms the voltage is about right. Since we know the uA is 500 we can simply add a resistor to verify.

[metasequoia]

Please allow me to clarify the situation; I am Doug Malone, the owner/designer/assembler/shipping dept. for voltagestandard.com.  Basically, I made an error and told forum member smoothtalker that a burden voltage of 1.55V was OK- I confused the 2V compliance voltage of DMMCheck with the 500mV compliance voltage of DMMCheck Plus.  The Fluke 116 has an unusually high burden resistance on its DC current range that makes it incompatible with DMMCheck Plus.  Per the suggestion on this forum I have updated the website to include compliance voltage for these two products along with a warning that the Fluke 116 can't be used to measure the DMMCheck Plus DC current output signal.  I also have offered smoothtalker a refund for his purchase including shipping (he declined the offer).
Regards,
Doug Malone

[Lightages]

It is nice to see you here Doug!

I am the guy in Chile. I have three of your devices and I think everyone who has dealt with you already know you are an honest and nice guy. I hope you stick around and join in on some of the conversations.