About the AN/APX-72

The Rex Systems AN/APX-72 Transponder System provides an integrated system for military and civilian vehicle identification, traffic control and altitude reporting in suitably equipped aircraft. The system may be installed in fixed or rotary winged aircraft as well as ships requiring identification. The system operates on mode 1, 2, 3/A, C and 4. System components are designed for easy interconnection and installation.


Download our AN/APX-72 Brochure


  • The World's most widely used military transponder system

  • Mark XII IFF Performance

  • DOD AIMS 65-1000 Compliance

  • Proven design with over 30,000 installations

  • Factory service available



  • DOD-AIMS-64-326B (MIL-R-81435)

  • DOD-AIMS-65-1000

  • MIL-Q-9858A Quality

  • Meets ISO9001:2008 (Quality Management System)

  • STANAG 5017

  • 1 CAO ANNEX 10 A, B, C

  • U.S. National Standards 1010.51A

  • J-STD-001 Class 3 Soldering Techniques Employed


Accessory Equipment

  • Antenna - Airborne AT-741/APX

  • Antenna - Shipboard AS-177B/APX

  • Power Supply - Shipboard PP-6099A/APX-72

  • Mating Connectors

  • Interconnect Cable

  • Extender Cards

  • Computer KIT-1A/TSEC or equivalent

  • Pressure Altitude Digitizer CPU-66/A or equivalent

  • Mount MT-3948/APX-72 (with isolators)



  • Spare Parts

  • Training and Logistic Support

  • Mating Conductors

  • Installation Materials

  • Complete Spares Support


System Components



The RT859A/APX-72 is the major component of the AN/APX-72 system. Installed in fixed or rotary winged aircraft or ships, it provides vehicle identification data, traffic control information and altitude reporting on properly equipped aircraft.

Upon receiving an interrogation from an external source, the RT859A/APX-72 decodes and processes the signal, and transmits the appropriate reply to all AIMS interrogators within range.


The MT3809/APX-72 die cast mount provides a rigid platform for transponder mounting allowing easy removal without vehicle altercation.

MT3948/APX-72 is the same mount with vibration isolators installed.

    Transponder Control

The C-6280A(P)/APX control allows the operator to select full range of transponder operating modes, reply codes, identifier pulses, and a self test. The mode 4 controls allow selection of reply light indicator or reply light and audio alarm. Indicator lights for mode 4 and self test are "press to test" types with adjustable intensity. The markings on the panel are illuminated from behind. thumbwheel and rotary switches are also illuminated. Installation is with standard aircraft turnlock fasteners.

    In-Flight Transponder Test Set

With the growing use of IFF Transponder Systems, it is increasingly important for pilots to know their IFF system is functioning properly. The TS-1843B/APX Test Set is designed for permanent installation in aircraft or ships as part of the IFF Transponder System. The test set is installed between the IFF Antenna and Transponder RT859A/APX-72. It monitors the performance of the transponder when it is "challenged" by signals from an external interrogator and causes a "TEST" light to illuminate on control panel C-6280A(P)/APX.


The test set can also generate its own interrogation of the transponder for a "self check" function when the control panel's "test" button is depressed. The TS-1843B/APX then evaluates receiver sensitivity, receiver tuned frequency, interrogation decoding, reply frequency, power and pulse spacing within preset limits as well as antenna line VSWR. If acceptable, the "test" lamp on control C-6280A(P)/APX will illuminate. Mount MT3513/APX is available for quick installation/removal.