National Instruments PXI-5691

To Next Page

GETTING STARTED GUIDE

NI PXI-5691

8 GHz RF Amplifier

Note Before you begin, install and configure your chassis and controller.

This document explains how to install, configure, and test the NI PXI-5691 (NI 5691). The

NI 5691 is a two-channel programmable RF amplifier that provides fixed gain and

programmable gain in a single-slot PXI module. The NI 5691 signal conditioning device ships

with the NI-5690 instrument driver, which you can use to program the device.

To access NI 5691 documentation, navigate to Start»All Programs»National Instruments»

NI-5690»Documentation.

Contents

Electromagnetic Compatibility Guidelines...............................................................................2

Unpacking the Kit.....................................................................................................................2

Preparing the Environment....................................................................................................... 3

Verifying the System Requirements......................................................................................... 3

Verifying the Kit Contents........................................................................................................ 3

Other Equipment...............................................................................................................4

Installing the Software.............................................................................................................. 4

Installing the NI 5691............................................................................................................... 4

Connecting Signals................................................................................................................... 6

Direct Connections to the NI 5691................................................................................... 6

Torquing SMA Connections............................................................................................. 6

Hardware Front Panel Connectors and Indicators............................................................ 8

Configuring the NI 5691 in MAX............................................................................................ 9

Programming the Device........................................................................................................ 10

NI-5690 Instrument Driver Examples............................................................................ 10

Making Your First Measurement.................................................................................... 11

Troubleshooting...................................................................................................................... 11

NI 5691 Does Not Appear in MAX................................................................................ 11

Module Fails the Self-Test.............................................................................................. 11

Why Is the ACCESS LED Off When the Chassis is On?...............................................12

Device Is Too Hot........................................................................................................... 12

Performance Issues Using an MXI Connection..............................................................12

Where to Go Next................................................................................................................... 13

Worldwide Support and Services............................................................................................13

Need help?

Do you have a question about the National Instruments PXI-5691 and is the answer not in the manual?

The NI PXI-5691 is an 8 GHz RF amplifier, a two-channel programmable RF amplifier designed for use within a PXI system. This single-slot PXI module offers both fixed and programmable gain capabilities, making it a versatile tool for various RF signal conditioning applications. The device is programmed using the NI-5690 instrument driver, which provides the necessary software interface for controlling its functions.

Function Description

The NI PXI-5691 features two distinct channels, CH 0 and CH 1, each with specific functionalities.

CH 0 (Fixed-Gain Amplifier): CH 0 IN and CH 0 OUT operate as a fixed-gain amplifier. This channel is characterized by a low noise figure and a flat frequency response, making it suitable for applications requiring consistent amplification across a broad frequency range. Both the input (CH 0 IN) and output (CH 0 OUT) of this channel are AC-coupled, meaning they block DC components of the signal.
CH 1 (Programmable Amplifier): CH 1 IN and CH 1 OUT function as a programmable amplifier with switchable main and direct paths.
- Main Path: This path offers fixed gain amplification in series with a step attenuator. The attenuator is adjustable in 0.5 dB nominal steps, providing fine control over the amplification level. The main path is AC-coupled, similar to CH 0, blocking DC signals.
- Direct Path: This path bypasses the programmable circuitry and routes the signal directly to the output. Unlike the main path, the direct path passes DC levels to the output, offering flexibility for applications where DC coupling is required.

The NI PXI-5691 is a precision RF instrument, and as such, it is sensitive to electrostatic discharge (ESD) and transients. Proper handling and connection procedures are crucial to prevent damage. External signals should only be applied when the NI 5691 is powered on, as applying signals while the device is off can cause damage. Users are advised to be properly grounded when manipulating cables or antennas connected to the IN connectors. For non-insulated devices like RF antennas, a static-free environment is recommended. Active devices such as preamplifiers or switches routed to the IN connectors must not generate signal transients exceeding the device's RF and DC specifications.

Usage Features

The NI PXI-5691 is designed for integration into a PXI chassis, requiring a PXI embedded controller or an MXI controller system. The installation process involves physically inserting the module into a supported PXI peripheral slot within the chassis. Chassis compatibility symbols guide users in identifying appropriate slots. Once installed, the module's front panel is secured with mounting screws. Empty slots in the chassis should be covered with filler panels or slot blockers to optimize cooling airflow.

Software installation is a prerequisite for operating the NI 5691. This includes installing an Application Development Environment (ADE) such as LabVIEW or LabWindows/CVI, followed by the NI-5690 instrument driver. The driver software media typically auto-runs the installer, guiding the user through the process. After installation, a system restart is usually required.

Configuration of the NI 5691 is performed using Measurement & Automation Explorer (MAX). MAX automatically detects installed devices and allows users to configure them. The device identifier assigned by MAX is used for programming the NI 5691. MAX also offers a self-test feature to verify hardware resources.

Connecting signals to the NI 5691 involves using shielded low-loss coaxial cables for optimal performance. SMA connections should be torqued to 100 N·cm using a standard SMA torque wrench, applying force until the wrench clicks. Before connecting any open-ended coaxial cable, it is recommended to momentarily short its center and outer connectors to discharge any potential capacitive charge.

The device's front panel includes ACCESS and ACTIVE LED indicators:

ACCESS LED: Indicates the basic hardware status. OFF means the module is not functional or has a PXI power rail problem. AMBER indicates the module is being accessed. GREEN means the module is ready to be programmed.
ACTIVE LED: Indicates the operational status. OFF means the module is in an uninitialized state. GREEN means the module is in a ready state or in use.

Programming the NI 5691 is done through the NI-5690 instrument driver within a supported ADE. Examples demonstrating device functionality and serving as programming models are available through the NI Example Finder (for LabVIEW/LabWindows/CVI) or from the Start menu (for C examples). These examples help users make their first measurements by launching the ADE, opening an example, selecting the device, and running the program.

Maintenance Features

Troubleshooting resources are provided to address common issues. If the NI 5691 does not appear in MAX, users are advised to refresh the device list, power cycle the system, and verify correct hardware installation. If the issue persists, navigating to the Device Manager (specific steps provided for Windows 8, 7, Vista, and XP) helps check for National Instruments entries or issues with PCI-to-PCI bridges for MXI controllers. Reinstalling the NI-5690 instrument driver may also resolve detection problems.

If the module fails the self-test, troubleshooting steps include restarting the system, re-running the self-test, power cycling the PXI chassis, reinstalling the module in a different PXI slot, and then powering on the chassis and re-testing.

Issues with the ACCESS LED remaining off when the chassis is on, even after configuration in MAX, suggest potential problems with chassis power rails, the hardware module itself, or the LED. The recommended steps include disconnecting signals, powering off the chassis, inspecting the module for damage, installing it in a different slot, powering on, verifying MAX detection, and performing a self-test.

The NI 5691 incorporates onboard sensors to monitor its operating temperature. Users can access this sensor data using the ni5690 Get Temperature VI or the ni5690_getTemperature function, which is useful for monitoring the device's thermal performance, especially in varying environmental conditions.

For systems using an MXI-3 connection, a specific MXI Optimization Application must be run before using the NI 5691 to prevent performance issues such as "time exceeded" or "internal software error" messages, initialization timeouts, or general performance degradation. This application typically runs automatically on Windows startup. If MXI software is not installed, users are directed to the MXI kit's setup instructions. MXI-4 optimization is handled automatically by the hardware.

Comprehensive support is available through National Instruments' website (ni.com/support) for technical assistance, troubleshooting, and application development. Additional services like factory installation, repairs, and extended warranties are also offered (ni.com/services). The NI RF Signal Conditioning Devices Help, an HTML manual, provides detailed information on RF fundamentals, device features, and programming.