TM 1-1520-238-10
3-12
3.6.3 Modes of Operation.
Depending on the setting
of the operating controls, the radio set can be used for the
following controlled modes of operation:
a. Transmit/Receive (TR) Mode.
Two-way in the
clear and secure voice communication. Refer to para-
graphs 3.8 through 3.8.2 for voice security system.
1. Set OFF,TR,-D/F mode select switch to TR.
2. Set EMER AM/FM,-MAN,-PRE frequency se-
lector switch to MAN for manual frequency
selection or to PRE for preset channel selection.
3. To manually select a frequency, rotate the four
MHz selector switches until desired frequency is
displayed at indicator windows.
NOTE
Rotating the MHz selector switches clock-
wise increases frequency. Frequencies can
be manually selected in 0.025 MHz incre-
ments.
4. To select a preset channel, rotate preset chan-
nel selector switch until the number of the de-
sired channel is displayed in the CHAN indicator
window.
NOTE
Clockwise rotation of preset channel selec-
tor switch will increase the desired channel
number (1 to 20). The radio set will automat-
ically tune to the preset channel in TR mode.
b. DF Mode.
Not Used.
c. AM Emergency (EMER AM) mode.
Emergency
two-way voice communication on selected guard channel.
1. Set mode select switch to TR.
2. Set frequency control/emergency select switch
to EMER AM.
NOTE
Selecting the EMER AM mode will automat-
ically disable the secure speech function
and enable clear voice communication.
d. FM Emergency (EMER FM) mode.
The FM
emergency mode enables voice reception/transmission
on a prestored guard frequency of 40.500 MHz.
1. Set mode select switch to TR.
2. Set EMER AM/FM,-MAN,-PRE frequency con-
trol/emergency select switch to EMER FM.
NOTE
Selecting the EMER FM mode will automati-
cally disable the secure speech function and
enable voice communication.
3.6.4 Operating Procedures, Radio Set AN/ARC-186.
a. Squelch Disable.
To disable squelch, set
squelch disable tone select SQ DIS/TONE switch to SQ
DIS. Squelch will remain disabled (open) until switch is re-
turned to center position.
b. Tone Transmission.
To transmit (FM or AM)
tone frequency of approximately 1000 Hz, set squelch dis-
able tone select SQ DIS/TONE switch to the momentary
TONE position. Releasing the switch removes the tone
frequency.
c. Loading Preset Channels.
1. Set mode select switch to TR.
2. Set EMER AM/FM-MAN-PRE frequency con-
trol/emergency select switch to MAN.
3. Rotate the four MHz selector switches until de-
sired frequency is displayed in indicator win-
dows.
4. Rotate CHAN preset channel selector switch
until the desired channel is displayed in the indi-
cator window.
5. Remove snap-on cover.
6. Momentarily hold WB-NB-MEM LOAD switch to
MEM LOAD. Preset frequency is now loaded
into memory.
