1. Active Frequency Display
3. Frequency Transfer Switch
4. Kilohertz (100's) Tuning Knob
5. Kilohertz (10's and Pull Out for 1 to 10)
6. Channel Switch
7. Power, Volume, and Mode Control Knob
8. Standby Frequency Display
Figure 3A-21. ADF Receiver Control Unit
(5) Kilohertz (10's and 1's) Tuning Knob.
The kilohertz 10's and 1's tuning knob is the smaller of
two concentric knobs, which are used to set the
frequency in the standby frequency display. Rotation
of the kilohertz tuning knob sets the 10's kilohertz
digits in the standby frequency display. Rotating this
knob while pulled out changes the 1 through 9-
kilohertz portion of the frequency. The numbers will
roll over at the upper and lower frequency limits.
Rotating the kilohertz 10's and 1's tuning knob in either
direction with the receiver control unit in the channel
mode will change the channel number and its
(6) Channel Switch. The channel switch,
placarded CHAN, is a push-button switch that will put
the receiver control unit into the channel mode when
momentarily pressed, or into the program mode when
held pressed for more than 2 seconds.
(7) Power, Volume, And Mode Control. The
power, volume, and mode control, placarded OFF,
VOL, PUSH MODE, controls operation of the receiver
control unit. Clockwise rotation from the OFF position
applies power to the system and continued clockwise
rotation increases volume.
(8) Standby Frequency Display. Displays the
standby (inactive) frequency.
c. Operating Procedures.
(1) Equipment Turn On. The receiver and
the control unit are turned on by clockwise rotation of
the power and volume knob.
(2) Frequency Selection.
When the receiver control unit is in the standby
frequency entry mode, the active frequency (in the
active frequency display) is selected by changing the
frequency in the standby frequency display, then
transferring the selected frequency to the active
frequency display by pressing the frequency transfer
switch. The frequency in the standby frequency
(hundreds) tuning knob and kilohertz (tens and ones)
tuning knobs on the receiver control unit. The receiver
control unit will remain tuned to the frequency in the
active frequency display as long as the receiver control
unit is in the standby frequency entry mode.
(b) Active Frequency Entry Mode. When
the receiver control unit is in the active frequency entry
mode, the active frequency (in the active frequency
display) is changed directly by rotating the tuning
knobs. The receiver control unit is changed to the
active frequency selection mode by holding the
transfer switch pressed for longer than 2 seconds.