[. . . ] Turn LARGE Knob Apollo SL30 Quick Reference Guide Standby Function Active Bearing To/From Graphic Small Inner Frequency Frequency Annunciators Indication CDI Knob Transmit Annunciator NAV/COMM COM A POLLO SL30 Comm Mode System Info Small Knob - kHz Nav Software Ver Large Knob - MHz Com Key - Monitor DSP Software Com Software Photocell PULL SQUELCH 118. 00 s136. 00 TX 135 to OBS T/F ID SEL A}}} ENT Low Display Intensity VOL Operation Summary System (SYS) Turn LARGE Knob High Display Intensity COM NAV SYS OFF Power/ Volume/ Squelch Frequency Flip/Flop Mode Select Comm Nav System OBS Radio Radio Settings Select Turn LARGE Knob Audio Ident To/From Enter Large Outer Knob Select NAV Nav Mode Nav Radio Info Small Knob - kHz Nav Key - Monitor Large Knob - MHz Nav Audio Level Additional CDI Info Press Nav/Com Mix Level SEL . [. . . ] A small "m" will replace the "s" in front of the Standby frequency. The From radial for the Standby channel is shown in parentheses when the VOR monitor mode is activated. This replaces the station identifier, OBS course, or VOR/LOC indicator. You cannot monitor a Localizer channel and the Nav audio is temporarily disabled while the system is monitoring the Standby VOR. Active Channel ILS XYZ Standby Channel Monitors VOR ABC Standby Channel Radial Graphic CDI Fly right 1. Press SEL and ENT again to disable the back course when it's appropriate. When Back Course is enabled, it is noted by "bc" on the display. Set the Standby channel to the appropriate VOR and note where a radial crosses the FAF and MAP for your approach. The internal CDI (on the right side of the display) and the external CDI, if installed, will guide you along the course to the runway. [. . . ] Using this feature, you may leave the audio enabled and then control it by an external audio panel. [. . . ]