Lubber
Line

Bearing

Pointer

Symbolic
Aircraft

Heading
Knob

Compass
Card

Figure 2: Bendix/King KI 227 ADF Indicator
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B. ADF Indicator
Figure 2 shows the Bendix/King KI 227 ADF indicator. It is located in the left-hand section of the instrument panel.
% The non-slaved ADF indicator has the following features:

%) Lubber line. It indicates magnetic heading of the airplane.

%) Bearing pointer. It indicates magnetic bearing to the station.

%) HDG knob. This knob rotates the compass card.

% The slaved ADF indicator has the following additional features:
%) Slaved compass card. It derives its heading input from the gyro compass system. Refer to
% Section 34-28 for details about the gyro compass system.

%) SYNC knob instead of HDG knob. The compass card is synchronized to the HSI compass card
% by rotating the SYNC knob until the heading matches that of the HSI.

C. ADF Antenna
The Bendix/King KA 44B ADF antenna is located on the lower side of the fuselage, under the baggage compartment. It has both loop and sense amplifiers, pre-amplifiers, and modulators. They combine the loop and sense antenna signals into a single RF signal.
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Trouble-Shooting
1. General
The table below lists the defects you could have with the ADF system. If you have the trouble detailed in the Trouble column read across to the Possible Cause column. Then do the repair given in the Repair column.
Trouble  Possible Cause  Repair 
ADF receiver does not operate.  Circuit-breaker not set. Faulty ADF receiver. Faulty cables/connectors.  Set the circuit-breaker. Repair or replace the ADF receiver. Do a test for continuity on each cable. Do a test for short circuit to ground and between cables. Replace defective cables. 
ADF indicator does not operate.  Faulty ADF indicator. Faulty cables/connectors.  Repair or replace the ADF indicator. Do a test for continuity on each cable. Do a test for short circuit to ground and between cables. Replace defective cables. 
ADF receiver unable to tune to  Faulty ADF receiver.  Repair or replace the ADF 
an AM broadcast station.  Faulty ADF antenna. Faulty connection between ADF antenna and ADF receiver.  receiver. Do a test for correct impedance of the antenna. If necessary, repair or replace the antenna. Ensure proper cable connections. Do a test for correct impedance of the antenna co-axial cable. Do a test for continuity on each cable. Do a test for short circuit to ground and between cables. Replace defective cables. 

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Trouble  Possible Cause  Repair 
No audio from ADF.  Faulty ADF receiver. Faulty audio system.  Repair or replace the ADF receiver. Trouble-shoot the audio system. Refer to Section 23-50. 

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Maintenance Practices
1. General
This Section tells you how to remove/install the components of the ADF system. It also tells you how to test the ADF system.
2. Remove/Install the ADF Receiver
A. Remove the ADF Receiver
Detail Steps/Work Items  Key Items/References 
(1)  Open the ADF circuit-breaker. 
(2)  Put a 3/32 Allen wrench into the access hole for the locking screw. Engage the screw.  Refer to Figure 1. 
(3)  Turn the screw counter-clockwise until the unit disengages from the mounting rack. 
CAUTION: DO NOT PULL ON THE KNOBS. DO NOT PRY THE FACE-PLATE. IF YOU PULL ON THE KNOBS, OR PRY THE FACE- PLATE, YOU CAN DAMAGE THE UNIT. CAUTION; DO NOT TOUCH THE CONNECTOR CARD AT THE REAR OF THE UNIT. THE ELECTROSTATIC CHARGE ON YOUR BODY CAN DAMAGE THE UNIT. 
　
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