(1) Compare Annunciator (ACT). ACT
momentarily illuminates when frequencies are being
changed. ACT flashes if the actual radio frequency is
not identical to the frequency shown in the active
(2) XFR / MEM Switch. This switch is a
3-position, spring-loaded toggle switch. When held to
the XFR position, the preset frequency is transferred to
the active display and the receiver re-tunes. The
previously active frequency becomes the new preset
frequency and is displayed in the lower window. When
this switch is held to the MEM position, one of the four
stacked memory frequencies is loaded into the preset
display. Successive pushes cycle the four memory
frequencies through the display (
2, 3, 4, 1, 2 ,3
(3) Frequency Select Knobs. Two concentric
knobs control the preset or active frequency displays.
The larger knob changes the three digits to the left of
the decimal point in 1-MHz steps. The smaller knob
changes the two digits to the right of the decimal point
0.05-MHz steps. Frequencies roll over at the upper
and lower limits. The two frequency select switches
are independent of each other such that the upper and
lower limit rollover of the 0.1-MHz digit will not cause
the 1.0-MHz digit to change.
(4) ACT Button. Push the ACT button for
approximately 2 seconds to enable the frequency
select knobs to directly retune the receiver. The
button window will display dashes and the upper
window will continue to display the active frequency.
Push the ACT button a second time to return the
control to the normal 2-display mode.
(5) TEST Button. Press the TEST button to
initiate the radio self-test diagnostic routine. (Self-test
is active only when the TEST button is pressed.)
(6) Light Sensor.
automatically controls the display brightness.
(7) STO Button. The STO button allows up
to four preset frequencies to be selected and entered
into the control's memory. After presetting the
frequency to be stored, push the STO button. The
upper window displays the channel number of
available memory (CH 1 through C4); the lower
window continues to display the frequency to be
stored. For approximately 5 seconds, the MEM switch
may be used to advance through the channel numbers
without changing the preset display. Push the STO
button a second time to commit the preset frequency
approximately 5 seconds, the control will return to
(8) Volume Control. A volume control is
concentric with the power and mode switch.
(9) Power and Mode Switch. The power and
mode switch contain three detented positions. The
ON and OFF positions switch system power. The
HLD position allows the NAV frequency to be
changed, but holds the DME to the current active
(10) MEM and HLD Annunciators. The NAV
control contains memory (MEM) and hold ( HLD)
annunciators. The MEM annunciator illuminates
whenever a preset frequency is being displayed in the
lower window. The HLD annunciator indicates that the
DME is held to the active frequency at time of
selection; the NAV frequency may be changed. The
upper window now displays the NAV frequency and
the lower window displays the held DME frequency.
(11) Preset Frequency Display. The preset
(inactive) frequency and diagnostic messages are
displayed in the lower window.
(12) Active Frequency Display. The active
frequency (frequency to which the VIR-32 receiver is
tuned) and diagnostic messages are displayed in the
c. Operating Procedures.
It is not practical to provide monitoring for
all conceivable system failures and, it is
possible that erroneous operation could
occur without a fault indication. It is the
responsibility of the pilot to detect such an
occurrence by means of cross-checks with
available in the cockpit.
(1) Equipment Startup. The VIR-32 receiver
and the CTL -32 NAV control are turned on by rotating
the power and mode switch on the NAV control to the
ON position. After power is applied, the CTL-32
displays the same active and preset frequencies that
were present when the equipment was last turned off.
selection is made using either the frequency select
knobs, or the XFR / MEM (transfer/memory recall
increases or decreases the frequency in the present
frequency display. The larger, outer knob changes the
frequency in 1-MHz increments (number to the left of