National Instruments NI 9251, Calibration Procedure, Page: 3 / 8

Table 1. Recommended Equipment (Continued)
Equipment Recommended Model Requirements
BNC (M) to BNC (M)
Coupler Pomona Electronics 3533 Characteristic impedance :
50 Ω
BNC F-F-F-T-Connector Pomona Electronics 3284 Characteristic impedance :
50 Ω
mXLR to BNC (M) Cable
(quantity 2)
NI 140150A-XXX
•
0R46 for 0.46 m
• 0R91 for 0.91 m
• 2R4 for 2.4 m
—
Chassis NI cDAQ-9178 —
Test Conditions
The following setup and environmental conditions are required to ensure the device meets
published specifications.
•
Keep connections to the device as short as possible. Long cables and wires act as
antennas, picking up extra noise that can affect measurements.
• Verify that all connections to the device are secure.
• Use shielded copper wire for all cable connections to the device. Use twisted-pairs wire
to eliminate noise and thermal offsets.
• Maintain an ambient temperature of 23 °C ± 5 °C. The device temperature will be greater
than the ambient temperature.
• Keep relative humidity below 80 %.
• Allow a warm-up time of at least 10 minutes to ensure that the device measurement
circuitry is at a stable operating temperature.
Initial Setup
Complete the following steps to set up the NI 9251 with mini XLR.
1.
Install NI-DAQmx.
2. Make sure that the NI cDAQ-9178 power source is not connected to the chassis.
3. Connect the NI cDAQ-9178 chassis to the system safety ground.
a)
Attach a ring lug to a 14 AWG (1.6 mm) wire.
b) Connect the ring lug to the ground terminal on the side of the NI cDAQ-9178 using
the ground screw.
c) Attach the other end of the wire to the system safety ground.
NI 9251 Calibration Procedure | © National Instruments | 3