Keithley 6487 User Manual page 56

Model 6487 User's Manual
Step 4. Connect the resistance to be measured to the picoammeter
Basic connections for ohms measurements are shown in
picoammeter INPUT and the V-SOURCE OUTPUT jacks are connected to the resistance
under test.
WARNING
Step 5. Select ohms function
Press the I|Ω key to make sure the ohms function is selected.
Step 6. Turn on voltage source
Press the OPER key to turn on the voltage source output. The VOLTAGE SOURCE
OPERATE indicator will turn on.
Step 7. Disable zero check and take a reading from the display
If the readings are noisy, use filtering to reduce noise. It may be advisable to use the
alternating voltage ohms, or add shielding.
NOTE
A safety shield is advisable whenever measurements are being made
with voltages over 30V DC. Connections for the safety shield are
shown in Figure
the noise shield or floating test circuit, and it must be connected to
safety earth ground using #18 AWG or larger wire.
For any ohms measurements, the ohms reading is invalid and unknown if the
voltage source is in compliance. Therefore, a value of -9.9e+36 will be returned
over the GPIB, and the message I-LIMIT will be displayed on the front panel for
both normal readings and buffer recall readings for any ohms readings where
the voltage source went into compliance.
Measurements and Sourcing Voltage
3-2. The metal safety shield must completely surround
Figure 3-2. Note that both the
3-9