Controls

PULL SQUELCH

VOL

OFF

Buttons

EC

MON

RCL

MEM

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.

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.

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