Beechcraft C-12C Operator And Technical Reference Manual page 255

FAULT CODE DESCRIPTION
00 No fault found
01 5 Vdc below limit
02 5 Vdc above limit
03 12 Vdc below limit
04 12 Vdc above limit
05 Synthesizer not locked
Noise squelch
07
signal
08 Noise squelch
signal
12 BCD frequency code invalid
13 2/5 frequency code invalid
14 Serial message invalid
3A-11. HF COMMAND SET (718U-5).
a. Description. The HF command set provides
long-range voice communications within the frequency
range of 2.000 to 29.999 MHz. The HF command set
employs standard Amplitude Modulation (AM), Lower
Sideband (LSB) modulation, or Upper Sideband (USB)
modulation. The distance range of the HF command
set is approximately 2,500 miles, and varies with
atmospheric conditions.
protected by the 3-ampere HF RCVR and the
25-ampere HF PWR circuit breakers located on the
overhead circuit breaker panel, Figure 2-16, Sheets 1
and 2. The associated antenna is shown in Figure
2-1.
Keying the HF radio set while operating the
ADF No. 2 set causes unreliable ADF
signals.
b. Controls and Functions, HF Command Set
Control Panel. Refer to Figure 3A-6.
(1) Frequency
frequency is selected by turning the frequency selector
controls until the desired operating frequency is
indicated. The controls may be operated in any order.
(2) MHz Indicators.
frequency of set.
(3) SQL Control.
adjusted to mute, undesired, background noise.
Table 3A-2. Self-test Codes (Continued)
open without
open without
The HF command set is
NOTE
Selectors. Operating
Indicates operating
The squelch control is
FAULT
15 Frequency out of range
16 Forward power below limit
17 Transmitter temperature excessive
21 Tuning voltage out of limit at highest receive
frequency
22 Tuning voltage out of limit at 118 MHz
23 Local oscillator output below limit
24 No-signal AGC voltage too high
25 Inadequate AGC voltage increase with rf signal
26 Reflected rf power above limit
27 Transmitter timed out
Setting the control too far counterclockwise can result
in blocking out weak signals. There are two different
types of squelch
configuration
configuration is the voice-operated squelch control that
functions to mute the receiver output in the absence of
a receive signal. The other type combines with RF
gain control.
control is different for the two configurations.
(4) RF TEST Indicator. Four conditions of
the RF TEST lamp indicate the operational status of
the system. The mode selector must be in the RF
TEST mode position.
with system unkeyed provides a lamp test of the RF
TEST lamp.
illuminated with the system keyed indicates the
operational status of the rest of the system.
(a) Illuminated.
receiver-exciter portion.
(b) Blinking.
amplifier-coupler.
(c) Extinguished. System is operational.
(5) Mode Selector.
determines operating mode.
(a) OFF. Turns set off.
(b) USB. Places set in Upper Sideband
mode.
TM 1-1510-218-10
CODE DESCRIPTION
control depending
installed in the aircraft.
Adjustment method of the squelch
Lamp illuminated or flashing
Lamp not illuminated, flashing, or
Indicates
Indicates fault in power
Turns set off and
on the
One
fault in
3A-13