Operating instructions

AVIONICS SYSTEM
B-11
Selecting the marker beacon tone frequency
When the [Outer Beacon], [Middle Beacon] or [Inner Beacon] key is pressed, the AF generator
will set to 400 Hz, 1.5 kHz or 3 kHz respectively. The tone frequency is shown in the display
alongside the appropriate marker designation.
The marker tone can be set to a frequency other than one of the three dedicated frequencies. It can
be set to any point within the AF generator range (20 Hz to 20 kHz) by first pressing the [AF
Freq] key, then using the data entry keys or by using the variable control to adjust the displayed
frequency. A standard frequency can be reset by pressing the appropriate beacon soft key.
When the displayed tone frequency is one of the marker frequencies, the appropriate marker
designation will also be displayed.
VOR
Selecting the VOR function displays the VOR screen and menu shown in Fig. B-3 on page B-5.
Setting the RF frequency
The RF frequency of the VOR test signal can be set to any 50 kHz increment within the VOR
range of 108 MHz to 118 MHz.
Attempting to set to a frequency outside the VOR range, or not at a precise 50 kHz increment
within the range, will cause the carrier to be set to the closest allowable frequency to it.
Pressing the [RF freq] key will highlight the 'RF Freq:' legend on the display and allow the
indicated frequency to be changed by using the variable control, or by using the data keys to enter
a new value.
The FREQ [⇑] or [⇓] increment keys can be used to change the RF frequency without selecting
[RF freq].
Setting the RF level
To change the RF level first press the [RF Level] key, then enter the required level using the data
entry keys or use the variable control to adjust the displayed frequency. See RF frequency and
level on page B-8.
Setting the subcarrier depth
The depth of modulation of the RF carrier by the 9960 kHz subcarrier is set by first pressing the
[Sub Depth] key and then entering the required value using the data keys and the [%] terminator
key or by adjusting the value by using the variable control.
The range of modulation depth available is 0 to 99%.
The depth of modulation of the subcarrier and the depth of modulation of the variable phase 30 Hz
signal can be locked to maintain the same value. This is achieved by pressing the [Lock Sub/Ref]
key which will display the legend ‘Ref/Sub Lock’ in reverse video and cause both modulation
depths to set to the value of the last modulation depth set. By keying in a new value or by
adjusting the modulation depth using the variable control, both levels will change.
Setting the 30 Hz reference tone modulation level
The depth of modulation of the RF carrier by the 30 Hz reference signal is set by first pressing the
[Ref Depth] key and then entering the required level of modulation using the data entry keys and
the [%] terminator key or by adjusting the value using the variable control.
The range of modulation depth available is 0 to 99%.
The subcarrier and reference tone modulation depth can be locked as described above.
Using the variable bearing facility
The phase relationship between the 30 Hz reference signal and the 30 Hz fixed signal from the
subcarrier can be varied with a resolution of 0.1° by using the variable control. The graphic
‘bearing indicator’ in the display will show the current bearing and a digital read-out is also given
in degrees.