Figure 1-11.-C-9245/ARC-161 control box.
The HF communication system consists of two
radio sets and interfacing equipment. These sets are
called HF-1 and HF-2. The two radio sets provide
two-way, single-sideband (SSB) and plain voice (AME)
communication in the frequency range of 2.0000 to
29.9999 MHz, and they automatically tune 280,000
channels at 100-HZ intervals. The HF-1 antenna has four
degraded frequency ranges at which coupling might not
be possible: 4.8000 to 6.0000 MHz, 12.0000 to 13.2000
MHz, 19.1000 to 20.3000 MHz, and 26.5000 to 27.7000
MHz. The HF-2 antenna has two degraded frequency
ranges where coupling might not be possible: 7.9000 to
9.1000 MHz and 18.9000 to 20.1000 MHz.
HF MAJOR COMPONENTS
Each AN/ARC-161 radio set in the HF
communications system consists of the following
components: a RT-1000/ARC-161 receiver transmitter,
an AM-6561/ARC-161 RF amplifier, a C-9245/
ARC-161 control box, a CU-2070/ARC antenna
coupler (which includes a lightning arrester), and a
long-wire antenna. Both radio sets share the use of a
TSEC/KY-75 security unit and TSEC/KY-75 remote
control unit.
RT-1000/ARC-161 Receiver Transmitter
The RT-1000/ARC-161 receiver transmitter
controls the radio tuning, coupler tuning, and mode
selection. It also contains all circuitry required for the
generating of transmitter signals and the processing of
received RF signals into audio/data signals.
AM-6561/ARC-161 Radio-Frequency Amplifier
This component amplifies the output of the RT prior
to transmission.
C-9245/ARC-161 Control Box
The C-9245/ARC-161 control box (fig. 1-11)
controls the operation of the HF radio set. There are two
of these in the aircraft, one for each radio set. They are
identical and interchangeable. Refer to figure 1-11 while
reading the following text.
1 through 6.
desired frequency
29.9999 MHz.
MHz select switches–Selects the
in the operating range of 2.0000 to
1-17
