PM501 Operation/Installation Manual Page 2 Revision 5, Jan 2003
Introduction
Congratulations on your purchase of a
PM501 intercom! We at PS Engineering wel-
come you to our family.
The PM501 is a panel mounted, 4-place
intercom that offers an intelligent low cost alter-
native for budget minded pilots who still want
quality sound and performance. This manual
provides information on the installation and op-
eration of the PM501. Please read it completely
before installation to reduce the risk of damage
to the unit and maximize your enjoyment of its
use.
Description
The PM501 is a 4-place, panel-mount inter-
com with individual output amplifiers for the
pilot, copilot, and passengers 1 & 2. The VOX
(Voice Activated Squelch) circuit prevents mic
audio from getting through the intercom until
someone speaks and automatically opens the
circuit. The volume control adjusts the level for
all headsets and functions as a PUSH-ON/
PUSH-OFF power switch.
The PM501 has an automatic, fail-safe con-
nection to the aircraft radio. In the event that
power to the intercom is lost, an internal relay
will immediately connect the pilot's headset di-
rectly to the aircraft radio.
A provision for an entertainment input al-
lows the pilot and passengers to listen to music
during flight. During intercom activity, this music
automatically mutes to allow communications
without distraction. Note: the music is NOT
muted during radio reception.
The 2-position switch acts as a mode selec-
tor. In the down position, the intercom is in the
ALL mode. Each position will hear the aircraft
radio, music, and each other. In the up position,
(ISO mode) only the pilot is connected to the air-
craft radio for undisturbed radio communications.
In ISO, the pilot is no longer on the intercom. All
others will continue to communicate with each
other and listen to music if desired.
With the PM501, both the pilot and copilot
have radio transmit capabilities. Only the person
who presses their Push To Talk (PTT) will be
heard over the aircraft radio. If both pilot and co-
pilot press the PTT, the copilot will override. The
pilot regains priority by switching the unit off.
Specifications
Input power: 12-28 Volts DC
Current Drain: < 70 mA Externally fused at 1 Amp
Headphone Impedance: 150-
1000
Ω
Typical
Total audio power available: 225 mW
Audio Distortion: <10% @ 75 mW into 150
Ω
load
Aircraft Radio Impedance: 1000
Ω
Typical
±3 dB Mic Frequency Response: 350 Hz-6000 Hz
±3 dB Music Frequency Response: 200 Hz - 15 kHz
Net weight: 8.5 Ounces (.340 kg)
Dimensions: 0.90" H X 2.60" W X 4.85" D
(2.2 cm x 6.6 cm x 12.3 cm)
FAA Approval – NONE
Note
: Installation of the PM501, using supplied hardware
and available wiring does not require special tools or knowledge
other than described in Advisory Circular 43.13-2. However, it
is the installer's responsibility to determine the approval basis for
this installation.
The PM501 is NOT FAA TSOd. To install
unit
in certificated aircaft, it may be necessary to use
FAA
form
337 or other approval may be required.
Front Panel View of PM501
Revision 5 Feb 2003 Page 7 200-118-0005
exclusion of limitation of incidental or conse-
quential damages, so the above limitation or ex-
clusions may not apply to your state.
Service
Call PS Engineering, Inc. at (423) 988-9800
and ask for a technician. He may be able to diag-
nose the problem and offer a solution without
the possible need for returning the unit. If the
unit does need servicing, ship product in UPS
approved packaging to:
PS Engineering, Inc.
Attn.: Service Department
9800 Martel Road
Lenoir City, TN 37772
Phone: (865) 988-9800
FAX (865) 988-6619
After the warranty period, PS Engineering of-
fers a low flat-fee repair for the life unit. Contact
the factory for details.
Appendix A
PTT Modifications
When received from the manufacturer, af-
ter-market PTT switches open the microphone
audio path to the "ring" connection of the PTT
mic plug. When the PTT is between the inter-
com and the headset, the intercom function will
not work until the PTT switch is depressed. A
simple modification can be performed to allow
proper intercom operation. NOTE: This modifi-
cation does not alter normal operation.
Procedures For David Clark's PTT
1 Unscrew the round black plastic cover from the
jack.
2 Connect the joined black wires to the red wire.
3 Replace the round black plastic cover.
Procedures for the Telex's PT-200
1 Unscrew the round black plastic cover from the
jack.
2 Cut the red wire in the middle of the wire
3 Strip both ends of the insulation
4 Solder the two ends to the ground lug to the PTT
jack
5 Replace the round black plastic cover
Procedures for the Telex's PT-300
1 Unscrew the round black plastic cover from the
plug jack
2 Remove the heat shrink material from the joined
black wires
3 Solder these two wires to the lug that has a white
already soldered to it.
4 Replace the round black plastic cover
These instructions represent typical after-
market switches. for more information, contact
the manufacturer.
Microphone
TIP
(PTT)
Ring
(mic audio)
Barrel
(gnd)
TIP
(phone audio)
Barrel
(audio
gnd)
Headphone