I. Product Introduction

NI SCXI-1190 is a four-channel 4×1 high-bandwidth RF/signal multiplexer module for high-frequency signal switching on the SCXI platform. It covers a bandwidth from DC to 1.3 GHz and is compatible with 50 Ω impedance systems. The module uses a single-pole double-throw (SPDT) relay and features low insertion loss and high isolation, making it suitable for selecting and routing RF, high-frequency analog and digital signals. It is now discontinued but spare parts and maintenance services are available.

II. Model Interpretation

SCXI: Instrument Signal Conditioning Expansion Series.

1190: The basic model, representing four groups of 4×1 high-bandwidth multiplexers with a bandwidth of 1.3 GHz.

Component Number: 186676D-01.

Difference: It is a different bandwidth version of the same series as SCXI-1191 (4 GHz) and SCXI-1192 (18 GHz).

III. Technical Parameters

Topology: Four independent 4×1 multiplexers (Quad 4×1 MUX), each group containing 4 input channels and 1 common output channel.

Bandwidth: DC to 1.3 GHz (-3 dB).

Impedance: 50 Ω (RF matching).

Switching Characteristics: SPDT relay, non-switching channels have no terminal matching (reflective type).

Rated Voltage: Maximum 24 V (AC/DC).

Rated Current: Maximum 1 A (24 V).

Insertion Loss: ≤ 0.5 dB (typical, 1 GHz).

Isolation: ≥ 60 dB (channel-to-channel, 1 GHz).

Relay Life: ≥ 5×10⁶ mechanical actions.

Power Supply: SCXI chassis backplane + 5 V power supply, power consumption approximately 3 W.

Temperature: Operating 0 to 55 ℃; Storage - 40 to 85 ℃.

Humidity: 5% to 95% without condensation.

IV. Interface and Communication Configuration

Front Panel: 8 SMA RF connectors, 4 common terminals (comA to comD), 16 signal inputs (ch0A to ch3A, ch0B to ch3B, ch0C to ch3C, ch0D to ch3D).

Back Panel: SCXI standard bus interface for power supply, control signal transmission and status readback.

Control Method: Controlled by NI-SWITCH driver, supporting development environments such as LabVIEW, C/C++, LabWindows/CVI, Visual Basic.

Communication Protocol: Based on SCXIbus serial instructions, supports independent control of a single module or cascaded synchronous control of multiple modules.

V. Core Functions

High-frequency Signal Routing: Four independent 4×1 multiplexers can select and route 16 high-frequency signals (DC to 1.3 GHz) to 4 common outputs, achieving centralized signal switching.

RF Matching Design: 50 Ω impedance matching, suitable for RF systems, reducing signal reflection and loss.

Low Loss High Isolation: Low insertion loss and high channel-to-channel isolation ensure the quality of high-frequency signal switching.

Flexible Topology Configuration: Can be configured by software as independent 4×1 MUX or combined expansion to meet different channel switching requirements.

Industrial-grade Reliability: Long relay life, resistant to vibration, electromagnetic interference, suitable for industrial and test site environments.

VI. Application Scenarios

RF Testing: In wireless communication, radar, RF component testing, multi-channel RF signal switching and routing.

High-Frequency Signal Monitoring: In ATE equipment, selection and measurement of high-frequency analog/digital signals (such as clocks, pulses, RF signals). Multi-channel signal scanning: A test system that requires polling 16 high-frequency signals and outputting them to 4 common channels.

Research laboratory: High-frequency signal distribution, switching and measurement, compatible with 50 Ω test systems.

Mixed signal system: Within the same chassis, in conjunction with other SCXI modules, to achieve mixed control of high-frequency and low-frequency signals.

VII. Usage and Maintenance Instructions Instruction Manual

Power-off installation: Insert the free slot in the SCXI chassis, tighten the fixing screws, and ensure the backplane bus is securely connected.

RF wiring: Use 50 Ω coaxial cable and SMA connector. Avoid excessive force to damage the connector; for non-switching channels, it is recommended to connect an external 50 Ω termination load to reduce signal reflection.

Software configuration: Install the NI-SWITCH driver, call the niSwitch Connect/Disconnect function in the development environment, and configure the channel switching logic.

Signal limitation: Strictly follow the rated voltage (24 V) and rated current (1 A). Do not input excessive power signals to avoid damaging the relays.

Prohibit hot swapping: Inserting or unplugging modules or RF cables while powered on is likely to cause damage to the relays, signal short circuits, or RF reflection damaging the signal source.

Maintenance instructions

Environment: Maintain ventilation and dryness, temperature 0-55 ℃, away from strong electromagnetic interference, dust, and corrosive gases.

Regular inspection: Check monthly for any looseness, oxidation, or damage to the SMA connector, and for aging or bending of the coaxial cable. Clean or replace promptly.

Cleaning: Wipe the connectors and panel with isopropyl alcohol to avoid liquid entering the module; strictly prohibit the use of corrosive cleaners.

Troubleshooting: When there is abnormal signal, prioritize checking RF connection, terminal load, driver configuration, and relay status; module failures are mostly due to relay aging or poor contact.

Long-term storage: After power-off, remove the module, clean the connectors, put on a protective cap, and store in an anti-static bag in a cool and dry place.