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Scalable RF Interface Unit


The Racal Instruments™ 1257A is a sixth-generation RFIU design with four Commercial Off-The-Shelf (COTS) options from 1U to 4U. It comes with a new easy-to-use LXI Core 2011-compliant device and new enhanced features. 

The Racal Instruments™ 1257A is a Commercial-Off-The Shelf modular RF interface unit (RFIU) that can be flexibly configured in order to meet specific application requirements. This unique scalable design enables you to select from a 1U to 4U size and specify the number, frequency range and switch topology of the relays to be installed by at the factory. Front pluggable relays with connectors enable easy service and high density within a small footprin

The 1257A RFIU offers an LXI interface based on Ethernet with a discovery and web-based interface. It incorporates many high-level software commands for easier programming and faster development. The design keeps track of all relay operations and sets alarms for end of life, so you will know when they need to be replaced. This ensures that they won’t fail in service or halt the production line.

The 1257A COTS RFIU’s offer flexible configuration, modular architecture, and scalability in order to preclude the need to design and fabricate a fully custom RFIU solution for many applications. The benefits of utilizing a COTS solution are lower costs, faster delivery, and easier replication.

In those rare cases where a standard 1257A is unable to meet specific application requirements, we also offer the 1257A-C, a fully-customized engineered and fabricated RFIU solution, and the 1257A-D, a complete modular developmental kit that enables you to configure and self-assemble your RFIU.

Applications for the 1257A
Common applications for the 1257A RFIU include the testing of communications equipment in production/installation/ commissioning and the operational monitoring of RF, Microwave, and radar signals. It can be used for base station, satellite antenna, or ATE test applications. 

Relays with a frequency range of up 40 GHz can be selected to accommodate a wide range of signal types. In many cases, the RFIU is utilized for routing and switching signals from one or more UUT’s or antennae to different RF test and monitoring equipment such as spectrum analyzers, frequency counters, and/or power meters.

Easily configured to your application requirements
In order to cost effectively address the wide range of application needs, the 1257A offers a broad range of pre-qualified relays that can be mixed and matched within the instrument chassis to suit individual requirements. The relays are front pluggable with connectors, and are available in a variety of frequency ranges, and switch topologies. Terminated or non-terminated relays, and extended life options are available.

Easy to Service and Support
Relays may be conveniently installed or removed from the front of the RFIU, and a full selection of pre-qualified spare relays are available for order. Additionally, relay counters provide visibility when components reach the end of their useful service life, enabling preventative maintenance instead of system downtime.

Easy to Control and Program
The 1257A comes standard with LXI/ Ethernet, USB, and GPIB control interfaces. A rich SCPI command set and IVI drivers provide easy integration and compatibility with almost all software environments. This new LXI interface is based on Ethernet and offers discovery and a web-based interface. Programming has been simplified with the incorporation of powerful and easy-to-use commands and features:

  • Path Names – Makes paths intuitive
  • Scan Lists – Set up a list the will run automatically 
  • Relay Counter – Counts relay closures and tracks relay end of life


Fully Documented System Performance
Prior to shipping, every specific path within the 1257A is fully tested. VSWR and insertion loss are typical measurements, with the validation plots for the applicable frequency range delivered on a CD with the product for customer viewing and future evaluation. This initial system characterization data often proves useful for quantifying the service life in electro-mechanical switches, troubleshooting, and for determining calibration factors.


Product Features: 
  • User-selectable standard configurations
  • 1U through 4U sizes, in rackmount or benchtop configuration
  • Choice of Dow-Key, Agilent, and/or Radiall relays with 18, 20, 26.5, and 40 GHz frequency options in terminated or unterminated relays
  • Choices of switch topology - SPDT, DPDT, 2xSPDT, 3xSPDT, SP3T, SP4T, SP6T
  • LXI/Ethernet, USB, and GPIB control interface
  • Scalable - up to 96 switch channels
  • Front-pluggable relays for easy expandability and replacement in the field
  • Relay counter