AVIONICS (COMMON) R T3 F3
Section I. GENERAL
This chapter covers all avionics equipment
common to the C-12R, C-12T3, and C-12F3 aircraft. It
provides a brief description of the equipment, the
technical characteristics, and locations. It covers
systems and controls, and provides the proper
techniques and procedures to be employed when
operational information consult the vendor manuals
that accompany the aircraft loose tools.
3-2. AVIONICS EQUIPMENT CONFIGURATION.
The aircrafts common avionics consist of two
groups of electronic equipment. The communication
group, which includes the HF communication set
(KHF-950) and the VHF communications transceivers
(VHF-22D), and the transponder and radar group, that
includes the APX-100 transponder.
Section II. COMMUNICATIONS
3-3. HIGH FREQUENCY COMMUNICATION SET
a. Description. The KHF-950 HF system
consists of three units: the panel mounted KCU 951
receiver/exciter. The system will operate on any 0.1
kHz frequency between 2,000 and 29,999.9 kHz.
With the capability to preset 99 frequencies for
selection during flight, the system allows for either
selection of other frequencies manually (direct tuning)
or reprogramming of any preset frequency. The
system will automatically match the antenna by keying
The HF system has two methods of frequency
selection. The first method is called direct tuning
(frequency agile). Th e second is a channelized
operation in which desired operating frequencies are
preset, stored and referenced to a channel number.
b. HF Control Panel and Functions. The
operating controls of the HF system are described in
the following paragraphs and are illustrated in Figure
(1) Frequency Display Displays frequency
(2) Mode Display Displays LSB, AM, or
USB indicating the mode.
(3) CHANNEL Display Displays channel
(4) Light Sensor The built-in light sensor
automatically controls the display brightness.
(5) Emission MODE Switch The emission
mode switch is a momentary push button that selects
LSB, AM or USB.
(6) FREQ / CHAN Switch Transfers the HF
system from a direct frequency operation to a
channelized form of operation.
(7) PGM Button Enables channelized data
to be modified. The PGM message will be displayed
whenever this switch is pressed. The program mode
must be used for setting or changing any of the 99
preset frequencies. Each of the 99 channels may be
preset to receive and transmit on separate frequencies
(semi-duplex), receive only, or transmit and receive on
the same frequency (simplex). The operating mode,
USB or AM, must be the same for both receive and
transmit and can also be preset.
selector consists of two concentric knobs that control
the channel and frequency digits, plus the lateral
position of the cursor.
(a) Frequency Control. The outer knob
becomes a cursor (flashing light) control with the
FREQ / CHAN switch in the FREQ position. The
flashing digit is then increased/decreased with the