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Controls Power/Volume/Squelch
The knob on the left side of the SL40 controls power
on/off, volume, and squelch test. Rotate the knob
clockwise (CW) past the detent to turn the power on.
Continuing to rotate the knob to the right increases
speaker and headphone amplifier volume level. Rotate
the knob to the left to reduce the volume level. Pull the
knob out to disable automatic squelch. The SL40 may be
installed to have the on/off switch disabled and to have
power controlled from the avionics panel.
Large and Small Knobs
The dual concentric knobs on the right side of the SL40
are used to select frequencies or to view the features
available within a function. Details are provided in the
appropriate section.
Buttons
Five backlighted buttons allow you to access the
functions in your Apollo SL40.
Flip/Flop (Arrows)
Press the Flip/Flop button to switch between the active
(left-most) and standby (right-most) frequency.
Switching between frequencies is disabled while you are
transmitting.
EC (Emergency Channel)
Press the EC button to load the Emergency Channel
(121.500 MHz) as the standby frequency. The Monitor
function is automatically enabled.
MON (Monitor)
Press the MON button to listen to the standby frequency.
When the active frequency receives a signal, the unit
will switch automatically to the active frequency.
RCL (Recall)
Press the RCL button to retrieve stored frequencies.
MEM (Memory)
Press the MEM button to store the displayed Standby
frequency in memory.
2
EC
MON
RCL
MEM
PULL
SQ
UEL
C
H
VOL
OFF