PXI-2598 26.5 GHz Dual-Transfer PXI RF Switch Module
The PXI-2598 is a dual-transfer PXI switch module designed for routing RF and microwave signals in automated test systems. It provides two independently controlled transfer switches, a nominal impedance of 50 Ω and operating bandwidth extending to 26.5 GHz.
The module can perform basic RF signal routing or insert and remove components from a signal path. Its low insertion loss, high isolation and controlled impedance make it suitable for microwave test, RF component characterization, signal-source selection and automated validation applications.
Key Features of the PXI-2598
- Two independent RF transfer switches
- 26.5 GHz maximum switching bandwidth
- 50 Ω nominal characteristic impedance
- Eight female SMA front-panel connectors
- Electromechanical latching relays
- Less than 0.7 dB insertion loss through 26.5 GHz
- Greater than 50 dB open-channel isolation through 26.5 GHz
- Maximum RF carry power up to 75 W at lower frequencies
- 1.25 Arms maximum carry current per channel
- 15 ms relay operate and release time
- 2.5 million-cycle expected mechanical relay life
- Onboard relay-count tracking
- PXI hardware trigger support
- PXI hybrid-slot compatibility
- NI-SWITCH and NI Switch Executive support
PXI-2598 Technical Specifications
| Product Model | PXI-2598 |
|---|---|
| Part Number | 778572-98 |
| Product Type | PXI RF and microwave transfer switch module |
| Switch Configuration | Dual transfer switch |
| Number of Relays | 2 |
| Number of RF Connections | 8 |
| Maximum Bandwidth | 26.5 GHz |
| Characteristic Impedance | 50 Ω nominal |
| Relay Type | Electromechanical, latching |
| Maximum Carry Current | 1.25 Arms per channel |
| Maximum Cold-Switching Voltage | 65 Vrms, CAT I |
| Maximum RF Carry Power | 75 W at frequencies up to 3 GHz |
| Minimum Recommended Switch Load | -35 dBm |
| Insertion Loss at 3 GHz or Below | Less than 0.2 dB |
| Insertion Loss at 8 GHz or Below | Less than 0.3 dB |
| Insertion Loss at 12.4 GHz or Below | Less than 0.4 dB |
| Insertion Loss at 18 GHz or Below | Less than 0.5 dB |
| Insertion Loss at 26.5 GHz or Below | Less than 0.7 dB |
| Open-Channel Isolation at 3 GHz or Below | Greater than 80 dB |
| Open-Channel Isolation at 8 GHz or Below | Greater than 70 dB |
| Open-Channel Isolation at 12.4 GHz or Below | Greater than 65 dB |
| Open-Channel Isolation at 18 GHz or Below | Greater than 60 dB |
| Open-Channel Isolation at 26.5 GHz or Below | Greater than 50 dB |
| Maximum VSWR at 26.5 GHz | Less than 1.7 |
| Insertion-Loss Repeatability | Less than 0.03 dB typical |
| Relay Operate and Release Time | 15 ms |
| Recommended Cycle Speed | 5 channels/s |
| Expected Mechanical Relay Life | 2.5 × 106 cycles |
| Input Trigger Sources | PXI trigger lines 0 through 7 |
| Minimum Input Trigger Pulse Width | 150 ns with digital filtering enabled |
| Output Trigger Destinations | PXI trigger lines 0 through 7 |
| Output Trigger Pulse Width | Programmable from 1 µs to 62 µs |
| Front-Panel Connectors | 8 × female SMA |
| Bus Interface | PXI hybrid |
| Module Format | 3U, two-slot PXI module |
| Weight | Approximately 302 g |
| Operating Temperature | 0°C to 55°C |
PXI-2598 Part Number and Accessories
| Item | Part Number | Description |
|---|---|---|
| PXI-2598 | 778572-98 | 26.5 GHz, 50 Ω dual-transfer PXI RF switch module |
| SMA Torque Wrench | 187106-01 | 1 N·m torque wrench for correctly tightening compatible SMA connections |
| SMA 100 Cable | 763443-01 | Approximately 0.15 m male-SMA-to-male-SMA flexible RF cable |
| SMA 100 Cable | 781846-01 | Approximately 0.30 m male-SMA-to-male-SMA flexible RF cable |
| SMA 100 Cable | 763444-01 | Approximately 0.38 m male-SMA-to-male-SMA flexible RF cable |
| SMA 100 Cable | 783470-01 | Approximately 2 m male-SMA-to-male-SMA flexible RF cable |
The PXI-2598 has eight female SMA connectors and does not require a terminal block. Select cables according to the required frequency, insertion loss, connector type and test-system layout. Use a calibrated SMA torque wrench to obtain repeatable RF performance and avoid damaging the connectors.
Dual-Transfer Switch Architecture
The PXI-2598 contains two independent transfer switches. Each transfer switch has four RF connections and two operating positions, allowing a pair of signal paths to be changed simultaneously.
This configuration is useful for switching a device into or out of a signal path while maintaining an alternate through connection. It can also exchange two sources or two loads without requiring several separate SPDT relays.
Inserting and Removing RF Components
A transfer switch can route an RF signal through a device under test in one state and through a bypass or reference path in the other state. This allows test software to compare the signal with and without the component connected.
Typical inserted components include filters, amplifiers, attenuators, mixers and calibration standards. The external paths should be designed with similar cable lengths and connector characteristics when accurate comparison measurements are required.
26.5 GHz Microwave Bandwidth
The PXI-2598 supports signals from DC through 26.5 GHz, covering many RF and microwave test applications. It can route high-order harmonics from an RF upconverter or connect different sources to an RF downconverter.
System bandwidth depends on every component in the signal path. Cables, adapters, fixtures and connectors must be rated for the highest required frequency and should be characterized when measurement uncertainty is important.
50 Ω Controlled Impedance
The module has a nominal characteristic impedance of 50 Ω, matching the impedance used by most RF generators, analyzers, digitizers and microwave measurement systems.
Maintaining a consistent 50 Ω environment helps reduce reflections, standing waves and amplitude errors. Unused ports and external branches should be terminated appropriately for the selected test configuration.
Low Insertion Loss
Specified insertion loss increases gradually with frequency, from less than 0.2 dB at frequencies up to 3 GHz to less than 0.7 dB through 26.5 GHz. This helps preserve signal power across the module’s full operating range.
The total test-path loss also includes cables, adapters, fixtures and connected devices. For calibrated measurements, characterize the complete path rather than compensating only for the switch module.
High Open-Channel Isolation
The PXI-2598 provides greater than 80 dB open-channel isolation through 3 GHz and greater than 50 dB through 26.5 GHz. High isolation helps reduce unwanted coupling between active and inactive signal paths.
Actual system isolation may be limited by external cables, connector spacing, fixture construction and signal leakage through other instruments. Use properly shielded microwave cables and avoid routing high-power signals close to sensitive receiver paths.
VSWR Performance
The PXI-2598 is designed to maintain controlled impedance across its operating bandwidth. Its specified VSWR remains below 1.7 through 26.5 GHz, with lower values at lower frequencies.
Good impedance matching reduces reflections and helps protect RF instruments from excessive returned power. Damaged SMA connectors or incorrectly tightened cables can significantly degrade VSWR performance.
RF Power Handling
| Frequency Range | Maximum RF Carry Power into 50 Ω |
|---|---|
| Up to 3 GHz | 75 W |
| Up to 8 GHz | 50 W |
| Up to 12.4 GHz | 35 W |
| Up to 18 GHz | 30 W |
| Up to 26.5 GHz | 25 W |
RF power capacity decreases as signal frequency increases. Verify both the module rating and the power-handling capability of every cable, adapter, termination and connected instrument before applying a signal.
Cold Switching and RF Source Protection
NI recommends avoiding the switching of active RF signals. During relay movement, the channel can become momentarily unterminated, creating reflections that may damage an RF source or affect measurement repeatability.
For cold switching, reduce or disable the RF output before changing the relay position. Apply the signal again only after the relay has completed its movement and the required settling time has elapsed.
Electromechanical Latching Relays
The PXI-2598 uses electromechanical latching relays. Latching operation allows the relay to maintain its selected position without requiring continuous coil power.
The relays have an expected mechanical life of 2.5 million cycles under suitable operating conditions. Electrical life depends on switched power, frequency, load, cycling rate and whether the module is operated using cold-switching practices.
Onboard Relay-Count Tracking
Relay-count tracking records the number of operations performed by each relay. Maintenance teams can use this information to monitor usage, estimate remaining service life and plan module replacement before unexpected downtime occurs.
Test developers can also distribute switching activity between equivalent paths when the system architecture permits, helping avoid excessive wear on a single relay.
Hardware Triggering
The PXI-2598 accepts input triggers and generates output triggers through PXI trigger lines 0 through 7. Hardware triggering allows relay operations to be coordinated with signal generators, analyzers, digitizers and other PXI instruments.
Trigger-based switching can provide more repeatable timing than software commands alone. The measurement sequence must still allow for the 15 ms relay movement time and any additional RF settling time.
Typical PXI-2598 Applications
- RF and microwave automated test equipment
- Signal-source selection
- Receiver and analyzer routing
- RF component insertion and bypass
- Filter and amplifier characterization
- Microwave device validation
- Aerospace and defense RF testing
- Wireless device production testing
- High-order harmonic routing
- Calibration-path selection
- Reference-path switching
- Research laboratory automation
RF Component Characterization
The PXI-2598 can switch a filter, amplifier, attenuator or other component between an active measurement path and a bypass path. Automated software can compare measurements between the two switch states without manually reconnecting cables.
For accurate results, account for the insertion loss, phase behavior and repeatability of both signal paths. A vector network analyzer or other calibrated RF instrument can be used to characterize the completed fixture.
RF Upconverter and Downconverter Routing
The module is suitable for passing high-order harmonics from PXI RF signal upconverters and routing multiple sources to RF downconverters. Its 26.5 GHz bandwidth supports microwave signals beyond the fundamental operating range of many RF instruments.
Confirm the harmonic frequency and power before selecting the switch path. The maximum permissible RF power decreases at higher frequencies.
Automated Calibration Paths
A transfer switch can select between a device-under-test path and a known reference path. This allows automated systems to perform verification or calibration checks without disconnecting the test fixture.
For precision RF calibration, use phase-stable cables and avoid bending or moving the cables after characterization. Mechanical movement can change cable loss and phase response.
NI-SWITCH Software Support
The PXI-2598 is controlled using the NI-SWITCH instrument driver. NI-SWITCH provides functions for initializing the module, changing relay states, configuring scan operations, using triggers and reading relay-count information.
The driver supports LabVIEW and compatible text-based programming environments. Test applications can coordinate RF switching with signal generation, acquisition and measurement analysis.
NI Switch Executive Integration
NI Switch Executive allows engineers to define meaningful route names instead of managing physical relay connections directly in every test program. Named routes can make large RF test systems easier to configure and maintain.
Switch Executive can also store RF path information used by the test system. This helps applications associate route-specific insertion loss or calibration data with the selected signal path.
PXI Hybrid Chassis Integration
The PXI-2598 uses a PXI hybrid bus connection and occupies two chassis slots. Before installation, confirm that two adjacent compatible slots are available and that the chassis provides adequate cooling.
Allow sufficient front-panel clearance for eight SMA cables. Support heavy or rigid cable assemblies so their weight does not place excessive mechanical stress on the module connectors.
PXI-2598 Troubleshooting
The PXI-2598 is not detected in NI MAX
Confirm that the module is fully installed in two compatible adjacent slots. Check chassis power, controller communication and NI-SWITCH installation, then restart the chassis and rescan the hardware.
A relay does not change position
Verify the selected relay and requested route in the application. Check for driver errors and confirm that another route is not reserving or conflicting with the same transfer switch.
The measured insertion loss is too high
Inspect all SMA connectors and cables for damage, contamination or incorrect tightening. Characterize the complete RF path and verify that every component is rated for the measurement frequency.
VSWR is higher than expected
Confirm that the system maintains 50 Ω impedance and that unused external paths are terminated correctly. Replace damaged cables or adapters and tighten SMA connections using the specified torque.
Isolation is lower than expected
Check for coupling through adjacent cables, fixtures or other instruments. Separate high-power and low-level signal paths and verify that the observed leakage does not originate outside the switch module.
The RF source reports excessive reflected power
Avoid changing relay states while the RF source is active. Disable or reduce the source output, operate the relay, wait for settling and then restore the signal.
Measurements are not repeatable
Inspect cable movement, connector torque, relay settling time and environmental temperature. Use phase-stable cables and compare the current relay count with the module’s expected service life.
The relay-count value is unexpectedly high
Review the test sequence for unnecessary switching. Reuse established routes when possible and distribute operations between equivalent paths if the system design permits.
Hardware triggering does not operate correctly
Verify the selected PXI trigger line, pulse width, trigger direction and digital-filter configuration. Confirm that the controlling instrument and PXI-2598 are not attempting to drive the same trigger line simultaneously.
PXI-2598 Comparison with Similar RF Switch Modules
| Model | Configuration | Bandwidth | Best Suited For |
|---|---|---|---|
| PXI-2598 | Dual transfer, 50 Ω | 26.5 GHz | Component insertion, bypass and paired-path switching |
| PXI-2798 | Four transfer switches, 50 Ω | 40 GHz | Higher-frequency systems requiring four transfer switches |
| PXI-2599 | Dual SPDT, 50 Ω | 26.5 GHz | Two independent source-or-load selection paths |
| PXI-2799 | Dual SPDT, 50 Ω | 40 GHz | Higher-frequency SPDT signal routing |
| PXI-2549 | Dual SPDT, 50 Ω | 2.7 GHz | Lower-frequency RF switching at reduced cost |
PXI-2598 vs PXI-2599
The PXI-2598 provides two transfer switches, while the PXI-2599 provides two SPDT switches. Both modules support 50 Ω RF signals through 26.5 GHz.
Choose the PXI-2598 when two signal paths must change together or when a component needs to be inserted and bypassed. Select the PXI-2599 when the application requires independent one-input-to-two-output or two-input-to-one-output selection.
PXI-2598 vs PXI-2798
The PXI-2598 provides two transfer switches and bandwidth through 26.5 GHz. The PXI-2798 provides four transfer switches and extends the supported frequency range to 40 GHz.
Select the PXI-2598 for systems that remain within 26.5 GHz and require two transfer-switch banks. Choose the PXI-2798 when additional switch density or operation above 26.5 GHz is required.
Recommended Related Products
- PXI-2798 40 GHz Four-Transfer RF Switch Module
- PXI-2599 26.5 GHz Dual-SPDT RF Switch Module
- PXI-2799 40 GHz Dual-SPDT RF Switch Module
- PXI-2549 Dual-SPDT RF Switch Module
- PXI-2547 8×1 RF Multiplexer Switch Module
- View More NI PXI and PXI Express Modules
Selecting the Right RF Transfer Switch
Choose the PXI-2598 when the application requires two transfer switches, 50 Ω impedance and operation through 26.5 GHz. It is particularly suitable for inserting or bypassing components and switching paired microwave paths.
Choose the PXI-2798 for frequencies extending to 40 GHz or when four transfer switches are required. Select an SPDT module such as the PXI-2599 when individual source or load selection is more appropriate than transfer switching.
Why Choose the PXI-2598?
- Routes RF and microwave signals through 26.5 GHz
- Provides two independent transfer switches
- Maintains a nominal 50 Ω signal environment
- Offers low insertion loss and high isolation
- Supports component insertion and bypass testing
- Provides eight standard SMA connections
- Supports PXI hardware triggering
- Tracks relay cycles for preventive maintenance
- Integrates with NI-SWITCH and NI Switch Executive
Frequently Asked Questions
What is the PXI-2598?
The PXI-2598 is a dual-transfer, 50 Ω PXI RF switch module designed to route signals from DC through 26.5 GHz.
What is the PXI-2598 part number?
The standard NI part number for the PXI-2598 is 778572-98.
How many transfer switches does the module provide?
The module contains two independently controlled RF transfer switches.
How many SMA connectors are installed?
The PXI-2598 provides eight female SMA front-panel connectors, with four connections for each transfer switch.
What is the maximum switching bandwidth?
The module supports RF and microwave signals through 26.5 GHz.
What is the characteristic impedance?
The PXI-2598 has a nominal characteristic impedance of 50 Ω.
What is the insertion loss at 26.5 GHz?
The specified insertion loss is less than 0.7 dB at frequencies up to 26.5 GHz.
What is the open-channel isolation at 26.5 GHz?
The specified open-channel isolation is greater than 50 dB through 26.5 GHz.
What is the maximum RF carry power?
The maximum is 75 W through 3 GHz. The rating decreases with frequency and is 25 W through 26.5 GHz.
Can the PXI-2598 switch an active RF signal?
NI recommends against switching active RF signals because the channel becomes momentarily unterminated during relay movement. Cold switching is preferred.
What type of relays does the PXI-2598 use?
It uses electromechanical latching relays with an expected mechanical life of 2.5 million cycles.
Does the PXI-2598 track relay operations?
Yes. Onboard relay-count tracking can help estimate relay life and schedule preventive maintenance.
Which software controls the PXI-2598?
The module is controlled through NI-SWITCH and can be integrated with NI Switch Executive, LabVIEW and compatible text-based development environments.
How many chassis slots does the PXI-2598 occupy?
The PXI-2598 is a 3U, two-slot PXI module and requires two adjacent compatible chassis slots.
Request a Quote for the PXI-2598
Contact us for current availability, lead time and project pricing for the PXI-2598 26.5 GHz Dual-Transfer PXI RF Switch Module. We can also help identify compatible SMA cables, torque tools, PXI chassis and related RF relay modules for your automated microwave test system.
