The National Instruments CAL-4330 Calibration Fixture (Part Numbers: 786988-01, 787003-01) is an essential tool designed to maintain the accuracy and reliability of the PXIe-4330 and PXIe-4331 devices. This fixture provides a controlled testing environment for adjusting various parameters, ensuring precise calibration. It is recommended to pair the CAL-4330 with a Fluke 5520A or 5522A calibrator, although other calibrators with similar specifications may also be employed if necessary. Key features include automated lead wire compensation, 2-wire output compensation, and the ability to handle resistance values ranging from 120 Ω to 1 kΩ with a resolution of 0.01 Ω and an accuracy of 90 ppm or better.

Included with the CAL-4330 are two 160-Pin DIN to 160-Pin DIN cables for connecting PXIe-2737 switch modules as well as a shielded cable (SH96F-96M-CAL4330) for linking the Device Under Test (DUT) to the fixture. To complete the calibration setup, two digital multimeters (DMMs), such as the PXI-4071 or PXIe-4081, are required, both of which should provide a multiranging capability with a 6 1/2-digit resolution. These DMMs must offer an accuracy of at least 40 ppm for DC voltage measurements and 80 ppm for 4-wire resistance measurements. Additionally, four PXIe-2737 switch modules are mandatory for effective relay operations.

To ensure exceptional performance and accurate readings, the fixture is designed for specific testing conditions. It is advised to utilize twisted-pair wiring to minimize noise and thermal offsets, employ shielded copper cables for connections, and keep cabling short to further mitigate interference. Stable operational conditions should be maintained at a relative humidity of less than 80% and an ambient temperature of 23°C ±5°C. It is also recommended to allow a minimum of 15 minutes for the measurement circuitry to stabilize prior to conducting tests, ensuring optimal results throughout the calibration process.