(b)  
Make sure the RDDMI narrow pointer shows 315 |5 degrees relative bearing (45 degrees left of lubber line) and a loud and clear audio tone (1020 Hz) is heard over the interphone.

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 (c)  
Set the mode switch to the ANT position.

 (d)  
Set the TONE switch to the ON position.

 (e)  
Tune the ADF to a known station, from below frequency, while you listen for a beat-frequency-oscillator (BFO) tone on the interphone. 1) Make sure the tuned frequency is within 1.0 kHz of the

 listed frequency and the BFO audio tone is loud and clear.

 (f)  
Set the TONE switch to the OFF position.

 (g)  
Tune the ADF to a known station in the 190 to 1750 kHz range. 1) Make sure the tuned frequency is within 1.0 kHz of the listed frequency.

 2)  Make sure the warning flag for the narrow pointer on each RDDMI is out of view and the audio reception is loud and clear.

 (h)  
Turn the GAIN control from maximum to minimum (counterclockwise). 1) Make sure there is a smooth change in the audio output

 level as you turn the control.

 (i)  
Make sure the audio output is available at each audio selector panel.

 (j)  
Set the mode switch to the ADF position.

 (k)  
Make sure the two RDDMI narrow pointers show the correct bearing for the station.

 (l)  
Detune the ADF receiver.

 1)  Make sure the warning flag for the narrow pointer on each RDDMI is out of view and there is no audio noise.

 (m)  
Set two other known stations in the 190 to 1750 kHz range, which are as widely spaced as possible. 1) Make sure the tuned frequency is within 1.0 kHz of the

 listed frequency. 2) Make sure the two RDDMI narrow pointers show the correct bearing and the audio reception is loud and clear.
 S 715-094
 (2)  
Do the ADF Bearing and Audio Test again with the TFR switch in the right position.

 S 715-072

 (3)  
Do the ADF Bearing and Audio Test again with the ADF-2 control panel, the RDDMI wide pointers, and the TFR switch in the right and left positions.

 G.  ADF Receiver Self-Test
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 S 745-105
 (1)  Do these steps to do a self-test of the ADF receiver:
 (a)  
Push and hold the test switch on each ADF receiver.

 (b)  
Make sure each test indicator moves to the TEST line (about 45 degrees).

 (c)  
Release the test switch on each ADF receiver.

 H. Put the Airplane Back to Its Usual Condition
 S 865-108
 (1)  
Set the mode switches to the OFF position.

 S 865-115

 (2)
Remove electrical power if it is not necessary (AMM 24-22-00/201).

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 AUTOMATIC DIRECTION FINDER SYSTEM - DESCRIPTION AND OPERATION
_____________________________________________________________
 1.  General_______
 A.  The ADF (automatic direction finder) system is a navigational aid that receives radio signals and determines the direction of the signals relative to the airplane. Signal sources utilized are standard broadcast and low frequency radio range stations operating in the frequency range of 190 to 1750 kHz. The system is used for either automatic or manual determination of compass bearing to a transmitting station, for reception of weather information and other broadcast programs, and for flying radio ranges.
　
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