I'm wondering how many of you are seeing the offset on DC current ranges?
For example my 10 day old 121GW, on the 500mA range, has about a 0.2 mA positive offset. Like Dr. Frank I'm likely going to do the offset calibration. My concern is that the offset varies over time. I've seen it as low as 0.07 mA and as high as 0.28 mA on the 500 mA range.
The offsets were about the same for the as shipped 1.22 firmware and the 1.51 firmware so no issue there or on DCV or any AC modes. As of now the offsets for the 5, 50, 500 mA ranges are 0.0016, -0.0019, 0.19 and the 5 A and 10 A ranges are -0.0018 A and -0.001 respectively.
Below is about 5 hours of logging at 10 per hour on the 500 mA range. You can see the randomness. The room temperature varied about 1.5C over the 5 hours. The first reading is anomalous (is that a bug?). No leads were connected per the calibration table except for one open lead in the mA/uA jack to activate the 5 and 50 mA range.
START,2018/10/03,22:53:01,
ID,170800000,
INTERVAL,300,sec,
,MAIN,,,SUB-1,,,SUB-2,,,Remark,
No. ,Func. ,Value,Unit,Func. ,Value,Unit,Func. ,Value,Unit,
1,DCA,-0003.51,mA,,,,,,,,
2,DCA,0000.24,mA,,,,,,,,
3,DCA,0000.19,mA,,,,,,,,
4,DCA,0000.16,mA,,,,,,,,
5,DCA,0000.22,mA,,,,,,,,
6,DCA,0000.18,mA,,,,,,,,
7,DCA,0000.17,mA,,,,,,,,
8,DCA,0000.17,mA,,,,,,,,
9,DCA,0000.19,mA,,,,,,,,
10,DCA,0000.16,mA,,,,,,,,
11,DCA,0000.20,mA,,,,,,,,
12,DCA,0000.16,mA,,,,,,,,
13,DCA,0000.18,mA,,,,,,,,
14,DCA,0000.18,mA,,,,,,,,
15,DCA,0000.18,mA,,,,,,,,
16,DCA,0000.19,mA,,,,,,,,
17,DCA,0000.19,mA,,,,,,,,
18,DCA,0000.20,mA,,,,,,,,
19,DCA,0000.24,mA,,,,,,,,
20,DCA,0000.22,mA,,,,,,,,
21,DCA,0000.14,mA,,,,,,,,
22,DCA,0000.19,mA,,,,,,,,
23,DCA,0000.19,mA,,,,,,,,
24,DCA,0000.26,mA,,,,,,,,
25,DCA,0000.13,mA,,,,,,,,
26,DCA,0000.22,mA,,,,,,,,
27,DCA,0000.26,mA,,,,,,,,
28,DCA,0000.15,mA,,,,,,,,
29,DCA,0000.23,mA,,,,,,,,
30,DCA,0000.22,mA,,,,,,,,
31,DCA,0000.19,mA,,,,,,,,
32,DCA,0000.22,mA,,,,,,,,
33,DCA,0000.22,mA,,,,,,,,
34,DCA,0000.18,mA,,,,,,,,
35,DCA,0000.25,mA,,,,,,,,
36,DCA,0000.21,mA,,,,,,,,
37,DCA,0000.23,mA,,,,,,,,
38,DCA,0000.25,mA,,,,,,,,
39,DCA,0000.15,mA,,,,,,,,
40,DCA,0000.20,mA,,,,,,,,
41,DCA,0000.15,mA,,,,,,,,
42,DCA,0000.14,mA,,,,,,,,
43,DCA,0000.26,mA,,,,,,,,
44,DCA,0000.22,mA,,,,,,,,
45,DCA,0000.21,mA,,,,,,,,
46,DCA,0000.23,mA,,,,,,,,
47,DCA,0000.20,mA,,,,,,,,
48,DCA,0000.17,mA,,,,,,,,
49,DCA,0000.18,mA,,,,,,,,
50,DCA,0000.28,mA,,,,,,,,
51,DCA,0000.26,mA,,,,,,,,
52,DCA,0000.20,mA,,,,,,,,
53,DCA,0000.23,mA,,,,,,,,
54,DCA,0000.26,mA,,,,,,,,
55,DCA,0000.24,mA,,,,,,,,
56,DCA,0000.22,mA,,,,,,,,
57,DCA,0000.21,mA,,,,,,,,
58,DCA,0000.21,mA,,,,,,,,
MAX,50,DCA,0000.28,mA,
MIN,1,DCA,-0003.51,mA,