II. Model Interpretation

PXI: Compliant with the PXI bus standard, compatible with PXIe hybrid slots

2548: NI RF switch series number, representing 2.7 GHz, four-channel SPDT, electromechanical relay

Alias: NI-2548, Quad SPDT, 4-SPDT RF Switch

Position: 4-channel independent SPDT general-purpose RF switch, flexible configuration, consistent paths, medium frequency, high-density integration.

III. Technical Parameters Basic parameters

Topology: 4 independent SPDT (Single Pole Double Throw), each channel's COM can be switched to NO or NCNI

Relay type: Electromechanical latch relay (EMR)

Frequency range: DC to 2.7 GHz (–3 dB) NI

Characteristic impedance: 50 Ω (nominal) NI

Channel count: 4 independent switches, each channel has 3 RF ports (COM/NO/NC)

RF performance (typical / guaranteed values)

Insertion loss:

≤1 GHz: <0.7 dB (typical)

≤2.7 GHz: <1.0 dB (typical < 0.8 dB)

Isolation:

1 GHz: >60 dB

2.7 GHz: >50 dB

VSWR: <1.5 (within 2.7 GHz, typical <1.3)

Maximum switching power: +24 dBm (continuous)

Terminal: No built-in terminal, supports external 50 Ω load

Electrical and dynamic

Maximum switching voltage: 30 VAC / 42 VDC NI

Maximum switching current: 0.5 A (per channel) NI

Switching time: Typical 5 ms (electromechanical)

Relay lifespan: 1 million times (typical), board-mounted counter tracking NI

Scan rate: 45 times/second NI

Physics and environment

I/O connector: 12×SMA female (4 channels × 3 ports, gold-plated)

Size: 3U PXI single slot (approx. 216×20×130 mm)

Weight: Approximately 260 g

Power consumption: 12 V ≈ 0.4 W

Operating temperature: 0 to 55 °C

Storage temperature: –40 to 70 °C

IV. Interface and Communication Configuration

Front-end interface

RF interface: 12×SMA female

Each SPDT: COM (common terminal), NO (normally open), NC (normally closed)

Trigger interface: No independent trigger, supports PXI backplane hardware trigger

Bus and control

Bus interface: Standard 3U PXI mixed bus (compatible with PXIe mixed slot) NI

Control software: Compatible with NI- SWITCH, MAX, LabVIEW, TestStand, Switch Executive NI

Driver support: NI-DAQmx, NI-VISA, provides VI and API function libraries

Trigger synchronization: PXI hardware trigger, nanosecond-level synchronization, supports multi-module cascading

Configuration method: Software independently controls 4 SPDT channels, supports single-channel switching and sequence scanning

Adaptation and expansion

Adaptation cable: SMA-SMA direct connection; optional SMA to BNC/SMB/MCX conversion

Expansion capability: Multi-module cascading, builds N×N matrix or large-scale multiplexer

V. Core Functions

4 independent SPDT flexible routing: Each channel can independently switch COM to NO/NC, achieving signal splitting, combining, instrument switching or path selection, suitable for complex test topologies NI.

DC to 2.7 GHz wideband coverage: Covers Bluetooth, WiFi, ISM, 2G/3G etc. in the medium and low frequency bands, meeting consumer electronics, industrial RF and general testing requirements NI.

Path consistency and low loss: 4 electrical paths are symmetrical, insertion loss is low, ensuring multi-channel test accuracy and consistency NI.

Relay lifespan management: Board-mounted counter counts the number of switching times for each channel in real time, predicts lifespan, reduces unplanned downtime NI.

PXI standard integration: 3U size in a single slot, seamless integration into PXI chassis, supports hardware trigger synchronization, compatible with automated ATE systems NI. No built-in terminal design: Flexible external connection of 50 Ω load, suitable for high-power or custom terminal scenarios.

Six. Application Scenarios

RF signal routing and switching: Channel expansion of instruments (signal sources / spectrum analyzers / network analyzers), antenna switching, path selection between DUT and instruments.

Construction of high-channel-count multiplexer: Cascading of multiple modules to form a large-scale SPDT matrix, maintaining consistent paths, suitable for multi-DUT parallel testing with NI.

Consumer electronics RF testing: Function verification and mass production testing of Bluetooth, WiFi, NFC modules, flexible switching of test paths and loads.

Research and development laboratories and solution verification: RF link debugging, matching test, multi-solution comparison, low loss to ensure test accuracy.

Semiconductor RF chip testing: Function verification, parameter testing, aging screening of medium-low frequency RF ICs, multi-channel parallel testing.

Seven. Usage and Maintenance Instructions

Usage Points

Installation: Standard 3U PXI single slot, lock the panel, ensure reliable contact of the backplane; avoid strong vibration and electromagnetic interference.

Connection: Lightly insert and remove SMA connectors, avoid violence; RF power ≤ +24 dBm,严禁 exceeding power； unused ports are recommended to be connected with 50 Ω terminations.

Power-on State： Default each COM is connected (normally closed)， NO is disconnected； without built-in terminal， external matching load is required to prevent reflection.

Software Control： Use NI-SWITCH or LabVIEW VI to control each SPDT； regularly read the relay count.

Environment： 0 - 55 °C operation， dust-proof， moisture-proof， and dew-proof； away from strong electromagnetic interference， ensure good grounding.

Maintenance Instructions

Regular Inspection： Check every quarter for any looseness， oxidation or damage of SMA connectors； clean the panel and ventilation ports， maintain good heat dissipation.

Life Management： Electromechanical relays approximately 1 million times； regularly read the onboard count， plan for replacement in advance to avoid downtime.

Fault Troubleshooting： First check SMA connection， external terminal and grounding； use MAX to diagnose switch status； take precautions against static electricity.

Storage： Power off when not in use， cover SMA connectors with a dust cap， dry and dust-proof storage， avoid high temperature， high humidity and strong magnetic fields.

Calibration： It is recommended to calibrate once a year to ensure that insertion loss， isolation， VSWR and other indicators meet specifications； you can contact NI or a third-party calibration institution.