User Guide

Series III Avionics
Pilot's Guide
Page 8
VCS-40A Notes
1. The FREQUENCY SELECTOR knobs tune the VC-401B transceiver directly. The display shows the
frequencies to which the VC-401B transceiver is actually tuned. The transceiver may also be tuned
by an ARINC 429 digital bus.
2. Display intensity and panel lighting are controlled by external dimmer controls.
3. Pressing and holding the FREQUENCY TRANSFER button for at least 7 seconds before releasing it
sets the COM frequency to 121.50 MHz. This is true even if segments of the display are faulty or a
lighting failure occurs. From this known reference point, any other frequency may be set by counting
detents of the FREQUENCY SELECTOR knobs as they are rotated. Each clockwise detent of the
outer knob is one Megahertz difference. Each clockwise detent of the inner knob is 25 or 8.33 kHz
difference.
4. The FREQUENCY SELECTOR knobs rotate continuously through all detents without end stops.
After rotating the outer knob clockwise to the highest number, the next detent will be the lowest
number (118 MHz).