NPX138N Series Panel Mount FM Transceiver
SM41 Installation and Operation Manual
Section 2 Rev: 1.00
Issue 4
Page 2-2
ENG-FORM: 805-0121.DOT
CONFIDENTIAL AND PROPRIETARY TO NORTHERN AIRBORNE TECHNOLOGY LTD.
2.4.1
Warnings
WARNING:
High volume settings can cause hearing damage.
Set the headset volume control to the minimum setting prior to
conducting tests, and slowly increase the volume to a comfortable
listening level.
2.4.2
Cautions
CAUTION:
Do not bundle any lines from this unit with transmitter coax lines. Do not
bundle any logic, audio, or DC power lines from this unit with 400 Hz synchro
wiring or AC power lines. Do not position this unit next to any device with a
strong alternating magnetic field such as an inverter or significant interference
to operation will result. In all installations, use shielded cable exactly as
shown and ground as indicated. Significant problems may result if these
guidelines are not followed.
All audio installations can be severely degraded by incorrect wiring and
shielding, and may result in much higher cross-talk, hum, and ground-loop
interference. This should be considered when audio wiring to and from the
radio installation is performed.
2.4.3
Notes
The case of the NPX138N must be electrically grounded for maximum resistance to low frequency
interference. A pin on the connector (Chassis ground) is provided and must be connected by a short wire
to a clean ground, not jumpered to the power ground wire connection.
Refer to the aircraft structural repair manual and maintenance manual for instructions and information
pertinent to this installation.
2.4.4
Cabling and Wiring
All wire shall be selected in accordance with the original aircraft manufacturer's Maintenance Instructions
or AC43.13-1B Change 1, Paragraphs 11-76 through 11-78. Unshielded wire types shall qualify to
MIL-W-22759 as specified in AC43.13-1B Change 1, Paragraphs 11-85, 11-86, and listed in Table 11-11.
For shielded wire applications, use Tefzel MIL-C-27500 shielded wire with solder sleeves (for shield
terminations) to make the most compact and easily terminated interconnect. Follow the interconnect
drawing in Section 2.5 as required.
Coaxial cable shall be selected in accordance with MIL-C-17 unless otherwise specified. Do not use coax
cable with PVC insulation. Teflon dielectric cable is encouraged at or above VHF frequencies or where
cable runs exceed 8 feet. Note that at VHF frequencies, cables losses due to long cable runs and tight
bends may reduce the ERP (Effective Radiated Power) by greater than 50%.
Allow 3" from the end of the shielded wiring to the shield termination to allow the connector hood to be
easily installed. Refer to the interconnect drawing in Section 2.5 for shield termination details. Note that
the hood is a "clamshell" hood, and is installed after the wiring is complete. Aircraft harnessing shall
The document reference is online, please check the correspondence between the online documentation and the printed version.
