User Guide

Series III Avionics
Pilot's Guide
Page 16
VNS-41A Notes
1. The FREQUENCY SELECTOR KNOBS tune the VNS-41A receiver directly. The display is directly
controlled by the receiver, so the frequency display shows the actual frequency to which the receiver
is tuned. The transceiver may also be tuned by an external ARINC 429 digital data bus.
2. The VOLUME control on the CD-412B control/display does not adjust the volume of the Marker
Beacon receiver in the VNS-41A receiver. This volume is preset. Typically, Marker Beacon volume
is adjusted by a control on an audio control panel.
3. Display intensity and panel lighting are controlled by external dimmer controls.
4. Pressing and holding the FREQUENCY TRANSFER button for at least 7 seconds before releasing it
sets the active frequency to 108.00 MHZ. Because the display is controlled by the receiver (see Note
1 above), the receiver will tune to this frequency even if the display is defective. From the known
reference of 108.00 MHz as a starting point, any other frequency may be selected by counting
detents. Each clockwise detent of the outer knob is one MHz difference (108, 109, 110, etc.). Each
clockwise detent of the inner knob is .05 MHz difference (.00, .05, .10, .15, etc.). For example,
rotating the outer knob clockwise three detents would put the frequency at 111.00 MHz. Then
rotating the inner knob clockwise three detents would then put the frequency at 111.15 MHz.
5. The FREQUENCY SELECTOR knobs rotate continuously through all detents without end stops. For
example, the next clockwise detent of the outer knob after 117 is 108; the next clockwise detent of the
inner knob after .95 is 00.