PS Engineering PM3000 - Manual (Page 5)

Page 8 200-193-0004 Rev. 4, Aug. 2003
phone channels off (silent) while the pilot, copi-
lot or passengers are not speaking. This reduces
background noise from the aircraft. Only when
someone speaks will their microphone turn on,
allowing the audio to pass through the system.
Although there is just one squelch control, there
are actually three separate squelch threshold cir-
cuits. One circuit each for the pilot, copilot, and
passengers. Only the microphone actually in use
is open, reducing noise in the system.
With the engine running, set the squelch control
knob by slowly rotating the squelch control knob
clockwise until you no longer hear the back-
ground noise in the earphones. When the micro-
phone is positioned properly near the lips, nor-
mal speech levels should open the channel.
When you have stopped talking, there is a delay
of about one half second before the channel
closes. This prevents squelch closure between
words, and helps eliminate choppy intercom
conversations.
3.3 Mode Select
The center switch is a mode control that allows
the pilot to tailor the intercom function to suit
flight conditions. Regardless of configuration,
the pilot will always hear the aircraft radio.
NOTE: If there is a power failure to the
PM3000, or if the power switch is turned off,
the copilot will not hear the aircraft radio. Only
the pilot is connected directly to the aircraft ra-
dio.
ISO (Up Position): The pilot is isolated from the
intercom and is connected only to the aircraft
radios. He will hear the aircraft radio reception
(and sidetone during radio transmissions). Copi-
lot and passengers will hear themselves and mu-
sic but not the aircraft radio traffic.
ALL (Middle position): All parties will hear the
aircraft radio, intercom, and music. However,
during any ICS conversation, the music volume
automatically mutes. The music volume in-
creases gradually back to the original level after
communications have been completed.
CREW (11932, 11934 only) (down position):
Pilot and copilot positions will hear aircraft ra-
dio and music number one. Passengers will only
hear other passenger’s intercom, and music
number 2. Music number two will not mute dur-
ing intercom conversation.
3.4 Music Mute Control
Mode Pilot Hears Copilot Hears Passenger Hears Comments
Isolate A/C Radio,
Pilot Sidetone
(during radio transmis-
sion) Copilot and passenger
intercom,
Music #1 Passenger and Copilot
intercom,
Music #1 This mode allows the
pilot to communicate with
the ground without the
copilot or passengers
bothered by the conver-
sations. Copilot and
passengers continue to
communicate and listen
All Pilot,
Copilot,
A/C Radio,
Passengers,
Music #1 Copilot,
Pilot,
A/C Radio,
Passengers,
Music #1 Passengers,
Pilot,
Copilot,
A/C Radio,
Music #1 This mode allows all on
board to hear radios as
well as communicate on
the intercom. Music and
intercom is muted during
intercom and radio com-
munications
Crew
(11932 11934 only) Pilot,
Copilot,
A/C Radio
Entertainment #1 Copilot,
Pilot,
A/C Radio
Entertainment #1 Passengers,
Entertainment #2 A second music source
is automatically enabled
for the passengers. Rear
music not muted.
Page 5 200-193-0004 Rev. 4, Aug. 2003
combinations can occur where minor interfer-
ence is possible. The PM3000 was designed in
an interference -protected chassis and has inter-
nal filter capacitors on all input lines.
Ground loop noise occurs when there are two
different return paths for the same signal, such
as airframe and ground return wire. Large cyclic
loads such as strobes, inverters, etc., can inject
audible signals onto the airframe return path.
Follow the wiring diagram very carefully to help
insure a minimum of ground loop potential. Ra-
diated signals can be a factor when low level
microphone signals are bundled with current
carrying power wires. Keep these cables sepa-
rated.
Insulating washers are required on all micro-
phone and headphone jacks to isolate them from
aircraft ground. The use of a conductor instead
of a shield for ground return eliminates these
ground loop paths.
2.4.2 Power Requirements
The PM3000 was designed to work with 12.8 to
27.5 volt DC negative ground systems. The
PM3000 must be externally protected with a one
ampere (1A) circuit breaker or fuse.
2.4.3 Sidetone
The PM3000 can be modified to produce side-
tone (hearing your voice during transmit), if the
aircraft radios do not produce it. Contact the PS
Engineering factory for details.
2.4.4 Entertainment Input
Stereo entertainment devices can be connected
to the PM3000. Install ⅛" stereo jacks conven-
ient the pilot and passengers to connect the en-
tertainment devices into the system. PM3000,
part number 11931 has a single entertainment
input. The part number 11932 will accommo-
date two inputs, one for the crew, and another
separate input that feeds the 4 passengers in
CREW mode.
It is possible to use only one entertainment de-
vice to provide music for both inputs in the
11932 system by connecting the output of the
entertainment device in parallel to both the Mu-
sic #1 and Music #2 inputs. We highly recom-
mend, however, that you install a switch be-
tween the entertainment device and Music #1.
This will give the pilot and copilot the ability to
switch off music while in the CREW mode.
The music device will automatically mute when
the ICS or aircraft radio becomes active. The
Soft Mute™ feature slowly returns the music to
full volume when the activity ceases. Pressing
the Mute disable switch (located on the squelch
control) in will inhibit this feature. Press again
to reactivate SoftMute. Music #2 will never be
muted during conversation and is heard only by
the passengers while the intercom is in the Crew
Use only low level output of the entertainment
devices to connect to the PM3000. Maximum
signal level on the input is 3-volts peak-to-peak.
DO NOT USE SPEAKER
OUTPUT LEVELS.
This will cause internal damage.
If speaker levels are to be used, install an
Audio Link, p/n 101PL2,
available from Crutchfield (1-800-955-3000).
Local oscillators and other internal signals
from CD or radio equipment can cause unde-
sired interference with VHF navigation and
communication equipment.
Before takeoff, operate the entertainment
device to determine if there is any adverse
effect on aircraft systems. If any unusual op-
eration is noted in flight, immediately switch
the entertainment device off