ing pointer will rotate 180. Use this heading to
and the bearing of one or two other radio stations is
fly outbound.
required. Make a position fix as follows:
d. Computing Time or Distance to Radio Station
(1) Set control unit function switch to ADF
and allow 5 minutes for warmup.
station as follows:
(2) Set BFO-OFF switch to OFF.
(1) Set function switch to ADF.
(3) Select the three radio station frequencies
(2) Set range switch to frequency range of
to be used and set range switch to fre-
radio station to be used. Tune station in
quency range of radio station with the
for maximum tuning meter indication.
lowest frequency:
Bearing indicator pointer will show bear-
(4) Tune station in for maximum tuning meter
ing of radio station.
indication.
(3) Maneuver airplane so that radio station is
(5 I Record bearing indicated on bearing indi-
at a relative bearing of 20" either aide of
cator and the time this bearing was taken.
nose of airplane. Record this bearing and
Correct bearing for local magnetic vari-
the time bearing was taken.
ation and draw a map plot for this radio
Hold a constant heading until the bearing
station, using figure 2-3 as a guide.
has doubled from 20 to 40 as shown in
Note. The narrow end of the bearing indi-
cator pointer always points to the radio station.
For a position fix, record the bearing indicated
The time required to fly to the radio sta-
at the opposite end (wide end) of bearing pointer
tion is equal to the time required for
( bearing from station).
doubling the bearing from 20" to 40
(6) Select radio station with next higher fre-
Distance is equal to the distance covered
quency and set range switch to this range.
while doubling the bearing angle.
(7) Tune station in for maximum tuning meter
indication, Record the time and radio sta-
2-5. Antenna Operation
tion bearing (I-searing from station ). Cor-
rect bearing for magnetic variation and
When the control unit function switch is set to
make a plot on the map.
ANT (antenna) position, the direction finder set
may be used either for reception of radio broadcast
(8) Setting range switch and TUNE control
stations or radio range navigation stations. In this
accordingly, take a bearing on the third
operating mode, the bearing indicator is inoperative.
radio station. The triangular intersection
of lines on the map plot is your position.
a. Radio Broadcast Reception.
c. Using Adf for Landing Field Approach (fig.
(1) Set the function switch to ANT.
2-4). A landing field approach procedure includes
(2) Set range switch to frequency range of
aircraft heading, distance, and time to landing field
desired radio station and tune in radio sta-
touchdown, using homing techniques, the outer
tion for maximum turning meter indication.
marker, or other radio facilities available in the
(3) Adjust GAIN control for desired sound
immediate area. A typical adf approach is shown by
level.
the dotted line in figure 2-4. The solid line indicates
b. Radio Range Navigation. A typical radio
the same heading to the radio station as that from
range orientation procedure is illustrated in figure
station to landing field. Proceed as follows:
2-6. Two airplanes are shown making a 180 turn
Set function switch to ADF.
for radio beam interception. Use this situation as
H o m e in on the radio facility (a(2)
a guide and proceed as follows:
through (6) above).
(1) Set control unit function switch to ANT.
While flying inbound on the final heading
(2) Set range switch to frequency range of
to the radio station or landing field, allow
radio range station.
sufficient time to correct for crosswind.
(3) While tuning the station in, adjust GAIN
Note. When flying toward the radio station
control for minimum audio output and
(inbound), the narrow end of the bearing indi-
tune for maximum tuning meter indication.
cator pointer will point to the station. After
As the range station in approached, the
passing over the station, the narrow end of bear-
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