I have a Radio Shack multimeter. When I set it to test capacitance on the nF scale it gives a reading of about .2 nF even when it's not connected to anything. The reading drops to about .18nF when I disconnect the test leads. Is there something wrong with my meter? Can I recalibrate it?

 

What Radio Shack multimeter?
What is the capacitance range in the specs?
200pF seems high to me. Meter might be faulty.

 

What Radio Shack multimeter?
What is the capacitance range in the specs?
200pF seems high to me. Meter might be faulty.

Thanks for reminding me to check the specs. It turns out that this meter can handle the caps I need to test. But that doesn't explain why it reads anything other than zero when nothing is connected to it. I don't see a model # on the meter but the user guide says it's a 42-Range Digital Multimeter and the cover of the guide has #2200811 on it in the corner.

 

Thanks for reminding me to check the specs. It turns out that this meter can handle the caps I need to test. But that doesn't explain why it reads anything other than zero when nothing is connected to it. I don't see a model # on the meter but the user guide says it's a 42-Range Digital Multimeter and the cover of the guide has #2200811 on it in the corner.

Try with the test leads pulled out. The cheap vinyl insulation can be a capacitor. 200pF seems a bit high but if the leads are dry (brittle), the stranded wires thin and partially oxidized, you will see some capacitance.

Now, what is the range in this meter? I'd it showing 000.2 nF or is it showing 200 pF? Very different in terms of "not showing zero".

 

here is the documentation I've found ....

 

here is datasheet:
http://support.radioshack.com/support_meters/doc67/67321.pdf

 

Does it have a knob to zero the reading when no capacitar is connected?

 

No there's no knob or other obvious adjustment to zero it. And, in response to some of the other questions, the reading is about .200nF (give or take, but it shows 3 places to the right of the decimal). And when I remove the leads from the meter, it drops to about .180nF. So the leads must have some capacitance but that's not the whole problem.

 

Hi,

You sure it is 0.200nf and not 0.200pf ?

If the range only goes down to 4nf maybe that is typical though.