Agilent/Keysight 44477A

The Agilent/Keysight 44477A is a VXI plug-in relay module providing seven independent SPDT (Form-C) relays for signal and power switching in automated test systems. It switches up to 2 A at 250 V DC, with maximum per-channel capacity of 60 W or 125 VA, and per-module capacity of 420 W or 875 VA. The module uses armature latching relays to maintain state, with contact resistance below 1 Ohm and thermal offset below 3 µV.

Scan rate reaches 43 channels/second, enabling fast sequential switching operations. The 44477A accommodates dual power configurations: external supplies up to 250 V DC or an internal 5 V DC supply. This flexibility suits applications requiring control of RF, coaxial, microwave components, and mercury relays.

Initial contact resistance below 1 Ohm minimizes signal loss and heat generation. The module integrates directly into Agilent/Keysight VXI mainframes such as the 3499A/B/C series, providing centralized switching control within larger measurement systems.

Technical Specifications

• Relay Type: 7 × SPDT Form-C relays


• Maximum Switching Voltage: 250 V DC


• Maximum Switching Current: 2 A per channel


• Maximum Power per Channel: 60 W, 125 VA


• Maximum Power per Module: 420 W, 875 VA


• Initial Closed Channel Resistance: < 1 Ohm


• Thermal Offset: < 3 µV


• Maximum Scan Rate: 43 channels/second


• Switching Mechanism: Armature latching relay


• Power Supply Options: External (up to 250 V DC) or internal 5 V DC

Key Features

• Armature latching design maintains relay state without continuous power


• Low contact resistance minimizes signal degradation


• Low thermal offset supports precision measurement applications


• High scan rate enables rapid multi-channel switching sequences


• Dual power supply configuration accommodates diverse system architectures

Typical Applications

• RF and microwave device switching


• Coaxial circuit control


• Mercury relay actuation via external power


• Automated test equipment signal routing


• Remote device drive and control

Compatibility & Integration

• VXIbus interface for plug-in integration


• Compatible with Agilent/Keysight VXI mainframes including 3499A/B/C series


• Form factor: VXI plug-in module


• Shipping weight: Approximately 3 lbs