AN/ARN-89B direction finder

DESCRIPTION-- DIRECTION FINDER SET

The Direction Finder Set (ADF) RCVR AN/ARN-89B, located in the pilot right console is used in conjunction with the VOR/LOC, gyromagnetic compass, and intercommunications systems. Also, the set is interfaced with both the RMI and HSI bearing indicators. The ADF set operates in the 100 to 3,000 kHz frequency range and is used to received continuous wave (cw) or amplitude modulated (am) radio frequency signals. The three modes of operation for the ADF set include automatic homing in the COMP mode, manual homing in the LOOP mode, and as a communications receiver in the ANT mode. A beat frequency oscillator is included to provide an audible indication for identification and tuning and is activated by the CW VOICE TEST switch.

CONTROL / INDICATOR

FUNCTION

1. TUNE indicator

Up deflection of the needle indicates most accurate tuning of the receiver.

2. CW VOICE TEST switch

VOICE

TEST

Provides tones that maybe used for identification, tuning, or CW station.

Permits normal aural reception.

Rotates ADF bearing pointer to provide a check of pointer accuracy with function selector in the COMP position, inoperative in LOOP and ANT positions. The switch is spring loaded away from TEST position.

3. Frequency selectors

Left ( course tune )

Right ( fine tune )

Selects first two digits of desired frequency.

Selects third and fourth digits of desired frequency.

LOOP control

Manual positioning of loop antenna when ADF is operating in manual direction finding mode.

Function selector

OFF

COMP

ANT

LOOP

Power off.

ADF operation as an automatic direction finder.

Receiver provides aural information only.

ADF operation as a manual direction finder using the loop antenna only.

6. AUDIO control

Adjusts receiver volume.