TM 1-1520-240-10
3-3-3
CONTROLS/
INDICATOR
FUNCTION
AUDIO Control
Adjusts audio level in
COMP position. Used as
RF gain control in LOOP
or ANT position.
LOOP Switch
When function switch is
set to LOOP, LOOP
switch enables manual
rotation of ADF loop an-
tenna and bearing indi-
cator pointer left or right
for manual direction
finding, or when homing
to a radio station. Re-
turning LOOP switch to
center position stops
rotation of bearing indi-
cator pointer at any de-
sired position.
Figure 3-3-2. Direction Finder Control
CONTROLS/
INDICATOR
FUNCTION
Coarse Tune Control
Tunes receiver in 100
kHz steps as indicated
by first two digits of KI-
LOHERTZ indicator.
Fine Tune Control
Provides selection of 10
kHz digits (continuous
tuning) as indicated by
last two digits of KI-
LOHERTZ indicator.
CONTROLS/
INDICATOR
FUNCTION
KILOHERTZ Indicator
Displays operating fre-
quency to which receiv-
er is tuned.
TUNE Meter
Provides indication of
relative signal strength
while tuning receiver to
specific radio signal.
CW-VOICE-TEST Switch
Three position toggle
switch. Spring-loaded
from TEST.
CW
Enables the beat fre-
quency oscillator (BFO)
to permit tuning to con-
tinuous wave stations.
VOICE
Enables the set to oper-
ate as an AM receiver.
TEST
Rotates the bearing indi-
cator approximately
180_ to check operation
of the set. The TEST
switch functions when
the function switch is at
COMP only.
3-3-7. Normal
Operation
—
Direction
Finder
Set. The following paragraphs discuss ADF set opera-
tion.
a. Starting.
(1)
Interphone control panel - Receivers NAV
switch — ON.
(2)
Mode switch — ON.
(3)
CW-VOICE-TEST — CW or VOICE.
(4)
Tune controls — Set frequency. Tune for
maximum signal strength on the tuning meter.
(5)
AUDIO control — Adjust.
b. ADF Operation.
(1)
VOR ADF switch on HSI MODE SELECT
panel — Press, if ADF segment is not lit.
(2)
Check for the correct bearing indication, on
HSI No. 2 bearing pointer.
c. Radio Receiver Operation.
(1)
Function switch — ANT
(2)
Tune control — Set frequency; then tune for
maximum signal strength on the tuning meter.
d. Aural Null.
(1)
CW-VOICE-TEST switch — CW.
(2)
Function switch — LOOP.
(3)
Loop switch — Rotate for audio and tune
indicator null. Release switch. Observe bearing to station
on indicators. Two null positions, 180_ apart, may be
obtained.
