
With the main tuning page displayed, the pilot
can use the rotary tuning knobs to scroll
through the frequencies stored in memory. By
pressing the line select key adjacent to the
preset frequency, the cursor will position over
the preset frequency. Pushing the line select
key a second time will cause the cursor to
move from the preset frequency to the MEM-
ORY nomenclature. Once the cursor is placed
around the memory nomenclature, the stored
memory values (maximum of 12) can be ex-
amined by turning the tuning knobs clock-
wise to increment and counter-clockwise to
decrement. As each memory location (chan-
nel) is selected, the stored frequency will be
shown on the COM preset line. A stored fre-
quency on the preset line can then be moved
to the active frequency position by depressing
the transfer key. Presets can also be viewed by
selecting COM or NAV MEMORY on the
RMU PGE MENU (Figure 16-9).
Another function available on the COM win-
dow is direct tuning. By pressing the line key
next to the preset frequency and holding it de-
pressed for approximately two seconds, the
preset frequency will disappear, and the yel-
low cursor box will now enclose the active
frequency. The active frequency can now be
changed directly by rotating the tuning knobs.
A TX will appear at the top of the COM win-
dow when the associated radio is transmitting.
Its purpose is to show the transmitter is on and
to alert the pilot in case of a stuck microphone
key. When the microphone is stuck for ap-
proximately two (2) minutes, a beep will sound
on the audio and a MIC STK message will ap-
pear at the top of the COM window until the
mic button is released. Ten (10) seconds after
the MIC STK annunciation appears, the se-
lected transmitter will automatically turn off.
A squelch function is associated with COM.
Depressing the SQ (squelch) function key at
the bottom of the RMU causes the COM radio
to open its squelch and allows any noise or sig-
nal present in the receiver to be heard. When
selected, a SQ will appear at the top of the
COM window. Pressing the button a second
time closes the squelch.
A NB or WB will appear at the top of the COM
window to indicate narrow bandwidth or wide
bandwidth is selected (Figure 16-10). Pressing
the top right transfer key while on the COM
memory page (Figure 16-11) will toggle the
receiver bandwidth from narrow to wide or
vice-versa. The power-up setting will be the
same as what was selected at power-down.
The narrow bandwidth is normally selected to
communicate with current generation ground
stations that have very tight frequency toler-
ance. In some areas of the world, that utilize
older ground equipment, wideband operation
is required to properly receive ground trans-
missions.
NAV Tuning Operation
The organization of the NAV window (top
right corner of the RMU) is identical to the
COM window in that the top frequency is ac-
tive and the bottom frequency is preset (Figure
16-10). The preset frequency will also have an
L E A R J E T 4 5
P I L O T T R A I N I N G M A N U A L
16-16
FOR TRAINING PURPOSES ONLY
FlightSafety
international
Honeywell
TUNE
SQ
DIM
1/2
STO
DME
TST
PGE
ID
COM 1
NAV 1
ATC/TCAS
ADF 1
TCAS DSPY
123.20
131.27
MEMORY-3
1471
1 ATC ON
RANGE:
40
BELOW
113.80
110.30
162.5
ANT
DME
H
NB
108.00
IPHX
Figure 16-10. DME Tuning on RMU