5840-00-448-0053 (86-18209)
NSN 5840-00-448-0053 (NIIN 00-448-0053) is a tuned cavity in Federal Supply Class 5840, Radar Equipment, Except Airborne — an inclosure, with a conductive inner wall, whose resonant frequency is determined by its internal dimensions. Manufacturer part number 86-18209 (Naples Research Corp., CAGE 52212); also referenced as FR144U (Joint Electronics Type Designation).
Key specs: aluminum body; 5.4 to 5.8 gigahertz frequency; full characteristics table below. NIIN assigned January 1961; export Schedule B 9030.90.8040.