I just got a Extech 845 clamp meter to replace the one that never came back after lending it to someone..
For what ever reason, the DC clamp function failed with a large OFFSET error. I used it once for this function to measure a load < 10 amps, and it correctly reported ~ 4 amps. The offset at that time was ~+/- 0.5 amps without using zero. I went to use that function again the next day, turn it on, select the DC clamp function and now I have an offset of -32 amps!
I can zero it however, I can't see how this could happen from simply turning it off one day and then on another day to have this happen?
I normally don't use such a device because I have other DC clamps I use for the O-scope that work fine. But this measures up to a 1000 amps is needed for those times, plus it has a IR temp for a ball park value which is great for doing component thermo-diagnostics in the field.
Using the offset mode does work but I feel the readings are now wrong, they are actually reporting only half of what I think they should be. Also to note, my other Extech also developed a large offset error in the DC mode for no apparent reason.
Is anyone familiar with this issue?
jamie