066-1062-10 – Honeywell Bendix King KT-76A ATC Transponder (Crown Series, 14V)
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Overview Section
The Honeywell Bendix King KT-76A is one of the most widely used Air Traffic Control (ATC) Transponders in general aviation history. The component's primary function is to reply to interrogations from ground-based radar sites (ATCRBS), providing air traffic controllers with critical information about the aircraft's position and, when connected to an altitude encoder, its pressure altitude.
The specific part number 066-1062-10 designates a particular configuration of the KT-76A:
KT-76A: The standard, TSO-certified, 4096-code Mode A and Mode C transponder.
-10 Dash Number: Identifies this as the Crown Series version, which features an all-black faceplate without the silver trim lining found on the "Silver Crown" models. There is no functional difference between the cosmetic versions.
Voltage: The KT-76A is inherently a 14 Volt radio. For installation in 28V aircraft, it requires the use of an external voltage changeover kit (a dropping resistor) to convert the 28V bus power to 14V for the unit.
Key Features Section
Mode A/Mode C Capability: Replies with the pilot-selected 4096 identity code (Mode A) and, when connected to an encoding altimeter, transmits pressure altitude in 100-foot increments (Mode C).
TSO Certified: Approved to TSO C74b, ensuring its reliability and performance meet FAA standards for ATC equipment.
Transmitter Power: Offers a robust 200 Watts peak minimum power output, ensuring reliable interrogation replies up to its certified altitude limit.
IDENT and Self-Test: Features a dedicated IDENT button to transmit a Special Identification Pulse (SPI) signal, causing the target on the controller's screen to "bloom" for immediate recognition. Includes a system test feature.
Side Lobe Suppression: Incorporates a 3-pulse side lobe suppression system to prevent unwanted replies from interrogations received via the side lobes of the ground antenna.
Direct Replacement: The KT-76A is a slide-in replacement for the older, low-power KT-78A transponder, offering a performance upgrade with no wiring changes.
Technical Specifications Section
Part Number: 066-1062-10
Model Designation: KT-76A ATC Transponder
OEM Manufacturer: Honeywell Bendix King
Transmitter Frequency: 1090 MHz (+/- 3 MHz)
Receiver Frequency: 1030 MHz
Output Power: 200 Watts peak minimum (Class 1A)
Input Voltage (Nominal): 14 VDC (Requires external dropping resistor for 28V operation)
Maximum Altitude: Certified for operation up to 35,000 feet
Dimensions: 6.25 inches W x 1.63 inches H x 10.0 inches L
Weight: Approximately 3.1 lbs (1.4 kg)
Aircraft Compatibility Section
General Aviation (GA): Used as the primary transponder in a vast number of legacy piston and light turbine aircraft (e.g., Cessna, Piper, Beechcraft).
Installation: Utilizes the same mounting rack and rear connector as the low-power KT-78A and is often considered a form/fit replacement for the newer KT-76C (though 28V installations of the KT-76A require attention to the dropping resistor).
Note: The installation and functionality of the KT-76A depend heavily on the external connections to the aircraft's power system and altitude encoder. The Bendix King KT-76A Installation Manual is the final authority for wiring and voltage requirements.
Applications Section
Air Traffic Control (ATC): Provides required two-way communication with ground radar to ensure safe separation from other air traffic.
Altitude Reporting: Transmits pressure altitude data when operating in ALT mode and connected to an encoding altimeter or blind encoder.
Emergency Signaling: Allows the pilot to set the emergency code (7700) or radio failure code (7600) for immediate ATC recognition.
Why Choose the 066-1062-10?
The 066-1062-10 provides a dependable, TSO-certified Mode A/C transponder solution that is a direct slide-in replacement for thousands of existing installations. While modern ADS-B compliant transponders (like the KT-74 or KT-76C) are often mandated for future flight, the KT-76A remains essential for aircraft not yet required to be ADS-B OUT compliant, or as an affordable replacement for a failed unit. Choosing the certified Bendix King unit guarantees the exact frequency stability, transmitter power, and receiver sensitivity necessary to reliably interact with the ground radar system.
The Mode C altitude reporting capability of the KT-76A is critical. It accepts parallel altitude data from a standard ICAO Altitude Transmission Code digitizer (encoder). The transponder converts this parallel data into a series of time-positioned pulses (called the Mode C reply) that communicate altitude to the ground controller. The unit's 14 VDC power requirement for the main radio unit is a major installation factor: in a 28 VDC aircraft, the external dropping resistor required for the 066-1062-10 dissipates the excess 14 volts as heat, necessitating careful placement in the aircraft's structure away from heat-sensitive components.
Note: The 066-1062-10 is an avionics component. It must be installed and certified by an FAA-licensed avionics technician. When replacing a unit, ensure the mounting rack (p/n 047-03898-0002 or 047-09628-0004) is used, and the voltage dropping resistor is correctly installed/verified for 28V systems.
Documentation
Honeywell Bendix King KT-76A Installation Manual: Essential for wiring, pin-out configuration, and 28V conversion procedures.
TSO C74b: Technical Standard Order governing this equipment.