UPS Aviation Technologies
SL10 Series Audio Selector Panel and Intercom System
Installation Manual
2-2
2.3.3 Mounting
Rack
Installation
2.3.3.1 Monaural (SL10, SL10M)
Remove the unit from the mounting tray by first removing the copilot volume and squelch knobs (the knobs
are press-fit on the shaft) and then unscrew the 3/32-inch hex-head screw that is to the right of the copilot
control knob shaft. Carefully slide the unit free of the tray. Set the unit aside in a safe location until needed.
Install the tray using six FHP 6-32 x ½-inch screws. The audio selector panel must be supported at front
and rear of the mounting tray.
2.3.3.2 Stereo (SL10S, SL10MS)
Remove the unit from the mounting tray by unscrewing the 3/32" hex-head screw that is to the right of the
squelch knob shaft. It is not necessary to remove the squelch knob. Carefully slide the unit free of the tray.
Set the unit aside in a safe location until needed. Install the tray using six FHP 6-32 x ½" screws. The
audio selector panel must be supported at front and rear of the mounting tray.
2.3.4 Connector
Assembly
The unit connectors mate directly with the circuit boards in the SL10. The connectors are a Molex crimp-
type, and require the use of a Molex hand crimp tool, EDP P/N 11-01-0203, CR6115B (or equiv.). The
connector is mounted to the unit tray with #4-40 screws, from the inside of the tray. Ensure that proper
strain relief and chafing precautions are made during wiring and installation.
2.4 Cable
Harness
Wiring
Referring to appropriate Appendix C, D, E and F, assemble a wiring harness as required for the installation.
All wires must be MIL-SPEC in accordance with current regulations. Two- and three-conductor with shield
wire must be used where indicated, and be MIL-C-27500 or equivalent specification. Proper stripping,
shielding and soldering technique must be used at all times. It is imperative that correct wire be used.
Refer to FAA Advisory Circular 43.13-2A for more information. Failure to use correct techniques may
result in improper operation, electrical noise or unit failure. Damage caused by improper installation will
void the UPS Aviation Technologies warranty.
2.4.1 Noise
Due to the variety and the high power of radio equipment often found in today's general aviation aircraft,
there is a potential for both radiated and conducted noise interference.
The SL10 power supply is specifically designed to reduce conducted electrical noise on the aircraft power
bus by at least 50dB. Although this is a large amount of attenuation, it may not eliminate all noise,
particularly if the amplitude of noise is very high. There must be at least 13.0 VDC present at the bottom
connector, pin 20, of the SL10 for the power supply to work in its designed regulation. Otherwise, it cannot
adequately attenuate power line noise. Shielding can reduce or prevent radiated noise (i.e., beacon, electric
gyros, switching power supplies, etc.) However, installation combinations can occur where interference is
possible. The SL10s were designed in a RFI hardened chassis and have internal Electromagnetic
Interference (EMI) filters on all inputs and outputs.
Ground loop noise occurs when there are two or more ground paths for the same signal (i.e., airframe and
ground return wire). Large cyclic loads such as strobes, inverters, etc., can inject noise signals onto the
airframe that are detected by the audio system. Follow the wiring diagram very carefully to help ensure a
minimum of ground loop potential. Use only Mil Spec shielded wires (MIL-C-275000, or better). Under no
circumstances combine a microphone and headphone wiring into the same shielded bundle. Always use a
2- or 3-conductor, shield wire as shown on the installation wiring diagram.
Radiated signals can be a factor when low level microphone signals are "bundled" with current carrying
power wires. Keep these cables physically separated. It is very important that you use insulated washers to
isolate the ground return path from the airframe to
all
headphone and microphone jacks.
Adding a high-performance audio control system, particularly in conjunction with active noise canceling
headsets, cannot improve on older avionics that were designed for cabin-speaker use. UPS Aviation
Technologies makes no claim that the audio panel will provide a noise-free audio quality under all
installation conditions, particularly with older avionics.
