Manual frequency selector (hundredths and
thousandths). Selects hundredths and thousandths digits of
frequency (00, 25, 50, or 75) in MHz.
Preset channel selector. Selects one of 20
preset channel frequencies.
Mode selector. Selects operating mode and
method of frequency selection.
selection of any one of 7,000 frequencies.
PRESET. Enables selection of any one
of 20 preset channels.
GUARD. Selection automatically tunes
the main receiver and transmitter to the guard frequency and
the guard receiver is enabled.
SQUELCH switch. Turns main receiver
squelch on or off.
VOL control. Adjusts volume.
TONE pushbutton. When pressed, transmits a
1,020 Hz tone on the selected frequency.
Function selector. Selects operating function.
OFF. Turns set off.
MAIN. Selects normal transmission
with reception on main receiver.
BOTH. Selects normal transmission
with reception on both the main receiver and the guard
ADF. Activates ADF or homing
system (if installed) and main receiver.
Turn on procedure:
Insure that aircraft power is on.
It is presumed that the avionics master
power switch is on, and that normally
used avionic circuit breakers remain
Avionics master power switch (over-
head control panel, fig. 2-12) - ON.
Function switch (UHF control panel,
fig. 3-3) - MAIN or BOTH position, as
If function selector is at MAIN setting,
only the normal UHF communications
will be received. If selector is at BOTH
position, emergency communications on
the guard channel and normal UHF
communications will both be received.
Receiver operating procedure:
UHF audio monitor switch (No.3, audio
control panel) - ON, or transmitter-interphone
selector switch (audio control panel) - No.3
Volume control (UHF control panel) - Mid
To use preset frequency (UHF control panel):
Mode selector switch - PRESET position.
Preset channel selector switch -Rotate to
To use non-preset frequency (UHF control panel):
Mode selector switch - MANUAL position.
Manual frequency selectors (5) - Rotate each
knob to set desired frequency digits.
The PRESET channel selector and
inoperative when the mode selector
switch is set to the GUARD position.
Volume - Adjust.