A later redesign into a largely solid-state system not only improved its performance (cutting the number of cabinets by more than half) also featured one of the best MTI (Moving Target Indicator) units in the fleet - a rarity in the early 1970s.

The CNO directed procurement, in advance of service approval, on 10 March 1959 to meet the schedule for the FRAM program and provide the radar frequency diversity required by OPNAV.

A separate Technical Evaluation, normally conducted in the contractor's plant, was not performed due to the compressed development schedule.

[2] It also incorporated the new AIMS IFF for air control of friendly aircraft, and a Low Flier Detection Mode (LFDM).

[3] The AN/SPS-40E replaces the tube-type power amplifier found on earlier versions with a solid-state transmitter and an improved cooling system.