066-1062-00 - Honeywell Bendix King - 14V ATC Transponder KT-76A

066-1062-00 – Bendix King KT-76A Mode A/C ATC Transponder (14V)

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Overview

The Honeywell Bendix King KT-76A, part number 066-1062-00, is one of the most successful and widely installed panel-mounted Air Traffic Control (ATC) transponders in the history of general aviation. This 14-volt unit is a flight-critical Line Replaceable Unit (LRU) designed to provide both Mode A and Mode C functionality, which are essential for aircraft identification and altitude reporting within the ATC system. Renowned for its exceptional durability, straightforward mechanical controls, and operational reliability, the KT-76A has been a staple in the instrument panels of countless piston-engine aircraft.

The KT-76A's primary function is to receive interrogation signals from ground-based secondary surveillance radar and reply with a pilot-selected 4-digit identification code (Mode A) and the aircraft's pressure altitude (Mode C). It is important to note that the KT-76A is a legacy avionics component. While it remains a robust and serviceable unit for its designed purpose, it does not meet the requirements for ADS-B Out mandated in much of the world's controlled airspace.

Key Features

• Proven Reliability and Durability: Known throughout the industry for its robust mechanical design and long service life.

• Mode A and Mode C Operation: Provides standard 4096-code squawk capability (Mode A) and pressure altitude reporting (Mode C) when connected to an encoding altimeter.

• Intuitive Mechanical Interface: Features large, easy-to-read, and glove-friendly mechanical thumbwheel selectors for squawk code entry, providing positive tactile feedback.

• Panel-Mounted LRU: Designed for standard panel mounting in a typical avionics stack for easy installation and replacement.

• Class 1A Power Output: A powerful 250-watt nominal transmitter output ensures a strong reply signal is received by both ground radar and airborne TCAS systems.

• Simple, Time-Tested Operation: Features a single function control knob (OFF/SBY/ON/ALT) and a dedicated IDENT button, making it one of the most straightforward transponders to operate.

Technical Specifications

• Part Number: 066-1062-00

• Model: KT-76A

• Component Type: ATC Transponder

• OEM Manufacturer: Honeywell Bendix King

• Modes of Operation: Mode A (4096 identification codes), Mode C (Altitude Reporting)

• Input Voltage: 13.75 VDC (for 14V systems)

• Power Output (Nominal): 250 Watts, Class 1A

• Certification: FAA TSO-C74c

Aircraft Compatibility

The KT-76A was a factory-standard or optional fitment on a vast range of 14-volt general aviation aircraft for several decades. It can be found on numerous models from:

• Cessna

• Piper

• Beechcraft

• Mooney

• And many other OEMs.

Note: This unit is a direct slide-in replacement for other KT-76A or KT-78A installations. Always consult the aircraft's equipment list and flight manual supplement to confirm eligibility.

Applications

• Air Traffic Control identification and altitude reporting in VFR and IFR conditions.

• A primary component for flight in airspace where ADS-B Out is not mandated.

• Can be paired with a separate 1090ES or UAT ADS-B Out solution (via STC) in some installations.

Why Choose 066-1062-00?

For aircraft operators who do not require ADS-B Out functionality or who already have a separate, compliant ADS-B solution, the KT-76A remains a highly reliable and cost-effective transponder. Its value lies in its proven, robust design, which is a known quantity for pilots and maintenance technicians alike. As a direct, slide-in replacement for a failed unit, it offers a simple and economical path to restoring essential Mode A/C transponder capability.

The Bendix King KT-76A is a key component in the Secondary Surveillance Radar (SSR) system, which forms the basis of modern air traffic control. The ground-based SSR radar transmits an interrogation signal on a frequency of 1030 MHz. The KT-76A's receiver circuitry is designed to detect these interrogations and identify them as either a Mode A or Mode C request. Upon receiving a valid interrogation, the transponder's transmitter replies on a separate, dedicated frequency of 1090 MHz. The reply is not a simple echo, but a coded sequence of digital pulses positioned between two standard framing pulses (F1 and F2). For a Mode A reply, the 12 data pulses represent the 4-digit octal "squawk" code set by the pilot. For a Mode C reply, the pulses represent the aircraft's pressure altitude in 100-foot increments, encoded using a Gillham code provided by an external encoding altimeter. This interrogate-reply system allows ATC to see not just a target, but a positively identified and altitude-reporting aircraft on their radar displays.

Note: This is a flight-critical avionics LRU. This is a Mode A/C transponder only and does not meet the requirements for ADS-B Out as mandated by 14 CFR §91.225 for flight in most controlled U.S. airspace. Installation, removal, and testing must be performed by a certified avionics technician. A transponder system certification check in accordance with FAR 91.413 is mandatory every 24 calendar months.

Documentation

Installation and operation manuals are proprietary to Honeywell Bendix King. All installation, maintenance, and testing procedures must be performed in accordance with the latest revision of the official KT-76A installation manual and the aircraft's maintenance manual. 

Item Specification