MD Helicopters 369-500, Инструкция по техническому обслуживанию

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CSP-HMI-3
MD Helicopters, Inc
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MAINTENANCE MANUAL
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97-04-00
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Copyright
©
1999 − 2016 by MD Helicopters, Inc.
and the speaker amplifier output is
connected to the external ramp hailer
speaker (if installed). In both PA and
EXT positions, any audio inputs
selected on the top row of pushbuttons
will be heard through the speaker until
MIC 1 or MIC 2 is keyed. Keying causes
the audio input to be muted and the
microphone audio to be heard. The P.A.
mute line may be used to mute the
normal passenger address audio while
MIC 1 or MIC 2 is keyed and the MIC
select switch is in the PA position.
In the EMG position, MIC 1 audio, #1
key, and primary headphones are
connected directly to COM 1, providing
fail-safe communication in the event of
a failure within the KMA 24H.
(4). VOX/VOL Controls:
Audio from the five intercom stations is
controlled by the two concentric knobs
at the far left of the panel. The inner
knob controls the ICS volume only, and
does not affect the other inputs. The
outer knob is used to select the desired
method of microphone activation: 1) hot
mic intercom (full CW), 2) VOX inter­
com (voice-operated intercom, middle
range), or 3) keyed activation of up to
five intercom stations (full CCW, key
thru separate ICS key switch).
In hot mike operation, all intercom
microphones remain active at all times
whether the operator is talking on the
intercom or not.
Voice-activated operation has the
microphone active only when the
operator begins to talk. When in the
VOX range, the outer knob adjusts the
sensitivity of the voice-operated switch.
In keyed operation, the operator must
depress a separate intercom switch to
activate the microphone for intercom
usage (Ref. Para. Intercommunication
System Description above).
In helicopters with the optional mode
select switch installed (Ref. Figure 2),
the VOX/VOL controls do not affect ICS
#1 or ICS #2 when in the Private mode
of operation (Ref. Modes of Operation
(Helicopters with Optional Mode Select
Switch Only)).
C. KMA 24H Control Panel Technical
Characteristics
Power Requirements
Idle current 500 milliamps
Max. operating current 1.8 amps
Instrument lights 260 milliamps
Input Impedance
320 ohms for all ICS inputs
500 ohms for all audio inputs
Input Isolation
60 dB between audio inputs
Speaker Muting
At least 55 dB when MIC is keyed
Isolate Muting
Pilot 55 dB
Copilot 55 dB
Max Rated Speaker Output
4 ohm tap 10 watts into 4 ohms
4 ohm tap 6.5 watts into 8 ohms
8 ohm tap 10 watts into 8 ohms
Maximum Rated Headphone Output
120 milliwatts into each 500 ohm load
Distortion
Less than 5% at max rated output
Less than 3% at 10% of max rated output
Frequency Response
Within 3 dB from 350 Hz to 600 Hz
D. VOX Sensitivity Level Adjustment
(1). Rotate VOX sensitivity control (outer
concentric knob) on KMA 24H control
panel to middle range for VOX opera­
tion.
(2). Rotate control CW until a hissing sound
is heard in the headphones, then rotate
control CCW until the hissing sound
stops.
NOTE:
The VOX is now properly set for the
present noise environment. It is normal to
have to reset the VOX sensitivity level
whenever the noise in the cabin changes,
such as when making large power setting
changes.