National Instruments 778572-98 PXI Transfer Switch Module

The National Instruments 778572-98 (or PXI-2598) is a Dual-Transfer Switch Module. It is designed for routing RF or microwave signals in automated test systems. It features a dual-transfer switch configuration that makes it ideal for basic signal routing and inserting or removing components in a signal path. This module is particularly suitable for passing high-order harmonics from PXI RF Signal Upconverter modules and routing multiple sources to PXI RF Signal Downconverter modules. This 778572-98 module is rated for Measurement Category I and is intended for signal voltages not exceeding 100 V. The maximum voltage requirement for cold-switching is 65 Vrms. It can carry a maximum current of 1.25 Arms per channel while offering the RF carry power up to 75 W for a 50 Ω load.

The 778572-98 dual-transfer switch unit offers excellent RF performance with a characteristic impedance of 50 Ω. Its insertion loss ranges from less than 0.2 dB at frequencies up to 3 GHz to less than 0.7 dB at frequencies up to 26.5 GHz. The voltage standing wave ratio (VSWR) remains low in this module. The unit provides substantial open channel isolation that exceeds 80 dB up to 3 GHz and maintains over 50 dB isolation up to 26.5 GHz. The 778572-98 also supports input and output triggers with software-selectable pulse widths. It requires 3.3 V at 2.5 W, 5 V at 1 W, and 12 V at 4 W from the PXI chassis. A Radiall relay (electromechanical, latching type) with contacts made of beryllium copper and gold-plated is used in this NI 778572-98 model. The relay operates and releases within 15 ms and the expected mechanical life of the relay is 2.5 million cycles. It supports a recommended cycle speed of 5 channels per second.

This NI PXI transfer module features 8 x SMA jacks for I/O connections, and the torque specification ranges from 0.8 to 1.1 Nm. The overall dimensions of the 778572-98 unit are 21.6 cm x 4.1 cm x 13.0 cm. It comes in a lightweight design and weighs only 302 grams. It is recommended to operate this module in ambient temperature ranging between 0 °C to 55 °C. The module is designed for indoor use and meets several safety compliance standards like IEC 61010-1, EN 61010-1, UL 61010-1, and CSA C22.2 No. 61010-1.