The KG-102 gyro forms the heart of the KCS-55A compass system because it supplies the basic heading reference as well as converts the aircraft power whether +14 or +28 VDC to the various voltage levels required by the other system units and for the gyro itself. The KG-102 Directional Gyro is a remote mounted unit which, in conjunction with the KMT-112 Magnetic Azimuth transmitter, provides a gyro stabilized magnetic heading to the KI-525A/525 Indicator. In addition to the slaving circuitry the KG-102 contains an internal power supply which provides gyro rotor power, excitation voltages for the Magnetic Azimuth Transmitter as well as positive and negative D.C. Voltages for the Pictorial Navigation Indicator and the Slaving Accessory. The KG-102 converts the flux valve slaving error to the proper digital format to be summed with the digital gyro signal that operates the stepper motor compass card drive in the KI-525/525A. The KG-102 accepts the auto and manual slaving commands from the KA-51A to control speed and direction of the slaving activity and finally, the KG-102 monitors the gyro spin motor to verify normal operation and sends a logic signal  for the heading loop drive motor to the KI-525/525A HDG flag to remove it from view when the heading signal is valid.

The KG-102 gyro supplies system power for the KCS-55A compass and is generated solely from the +14 VDC or +28 VDC aircraft power. From this source, the following internal supplies are generated: 26 VAC, 400 Hz for the gyro spin motor and flux valve excitation; ±15 VDC regulated supply for linear circuitry in the system; +15 VDC unregulated voltage for the KI-525/525A stepper motor drive plus the system logic circuitry, the glideslope pointer and power flag current, and +5 VDC regulated supply for the LED drive current in the KI-525/525A and slaving drive circuits. The KG-102 is shock mounted weighing at 4.3 pounds with an operating temperature of -55° C to +55° C.