4-Wire Ohms Function; Offset Test - HP 3457A Service Manual

Performance Tests
4-Wire Ohms Performance Tests Cont'd
4-34. 4-Wire Ohms Function
-
Offset Test
4-35. Equipment Required. A low thermal short (copper wire) is required for this procedure.
1. Set the HP 3457A to the 4-Wire Ohms Function (OHMF) and the number of digits displayed
(DIGITS DISP) t o six.
2. Short the front panel input terminals of the HP 3457A as shown in Figure 4-6.
3.
Use the Test Record t o record the offset readings of the 30 Ohm, 300 Ohm. 3 Kohm, 30 Kohm,
300 Kohm, 3 Mohm, and 30 Mohm ranges.
4. If any of the offset readings are beyond the limits specified in Table 4-9 and on the Test Record,
the instrument should be calibrated or repaired. Refer to Section V of this manila1 f o r calibration
procedures.
5. Remove the short from the front panel input terminals.
Figure 4-7. 4-Wire Ohms Gain Performance Test Connections
3457A
I npu t
S h o r t
S h o r t
S h o r t
S h o r t
S h o r t
S h o r t
S h o r t
Table 4-9. 4-Wire Ohms Offset Test Limits
3457A
Range
30 ohm
300 ohm
3 Kohm
30 Kohm
300 Kohm
3 Mohm
30 Mohm
3457A
Set Up
O H M F
O H M F
O H M F
O H M F
O H M F
O H M F
O H M F
9 0 day l i m i t s
00.00335 ohm
000.0035 ohm
0.000007 Kohm
00.00007 Kohm
000.0008 Kohm
0.000014 Mohm
00.00083 Mohm
1 year L i m i t s
00.00335 ohm
000.0035 ohm
0.000007 Kohm
00.00007 Kohm
000.0008 Kohm
0.000014 Mohm
00.00083 Mohm