Specifications

SECTION III
INSTRUMENTATION AND AVIONICS
MODEL 560
HONEYWELL PRIMUS II REMOTE RADIO SYSTEM - ADF
The automatic direction finder (ADF) function of the Primus II remote radio system is provided by the
DF-850 ADF receiver module which is a component of the RNZ-850 integrated navigation unit. As
discussed in the COM section above, the tuning of the complete system, which includes the ADF, is
accomplished by means of the remote management unit (RMU), the RM-850.
The receiver has a frequency range of 100.00 to 1799.5 KHz in 0.5 KHz increments. A strap
selectable option is available which allows tuning of marine emergency frequency of 2181 thru 2183 KHz.
Four modes of operation are available on the DF-850 ADF: ANT (Antenna), ADF (Automatic Direction
Finder), BFO (Beat Frequency Oscillator), and VOICE. In ANT mode, the ADF receives only and does not
compute bearing information. In ADF mode, the system receives signals and computes relative bearing to
station. In BFO mode, a beat frequency oscillator is added to the signal for reception of CW signals. In
VOICE mode, the reception bandwidth is widened for improved voice audio on the frequency. The VOICE
mode is not used for navigation. Bearing information is available only in ADF and BFO modes. If ANT is
used for tuning, random ADF needle searching is prevented. The modes are selected by pressing the
lower line key adjacent to the ADF window. Progression is: ANT; ADF; BFO; and VOICE. The mode
changes each time the line key is pressed. When the tuning cursor (amber box) surrounds the lower ADF
Line, the ANT, ADF, BFO, and VOICE progression may also be selected by turning the tuning knob.
When the line select key adjacent to the frequency window of the ADF is pressed, the cursor will
move to the ADF frequency window and the ADF may be tuned by the tuning knobs. Tuning will increment
in steps of 0.5 KHz with the small knob and 10 KHz with the large knob. If the knobs are turned faster,
larger increments are selected for each turn enabling large changes to be made in much less time. The
rate of increased tuning speed is proportional to the rate the knobs are turned. The
ADF has a "scratch
pad"
memory which will store one frequency. This is accomplished by selecting the desired frequency and
pressing the STO button for two seconds. To retrieve the frequency from memory, press the line select
key adjacent to the ADF frequency window for two seconds.
The ADF bearing information may be selected on the "O" bearing needle of the pilot's electronic
primary flight display (PFD). If dual ADFs are installed, the "
~ " bearing pointer will display ADF 2, when
selected. Selection is accomplished by means of the bearing knobs (O and
~ ) on the respective DC-550.
Figure 3-15. PRIMUS II ADF Controls
I 3-30 Configuration AA 56OMB-01