AEM SM46, Installation And Operation Manual

Page: 14 / 55

N335 Series Audio Controller
SM46 Installation and Operation Manual
May 18, 2012 Rev: 2.00 Page 2-2
ENG-FORM: 805-0100.DOTX
CONFIDENTIAL AND PROPRIETARY TO ANODYNE ELECTRONICS MANUFACTURING CORP.
2.4.1 Warnings
WARNING:
High volume settings can cause hearing damage.
Set the headset volume control to the minimum volume setting prior to
conducting tests, and slowly increase the headset volume to a
comfortable listening level.
2.4.2 Cautions
CAUTION:
Do not remove components from the product while the unit is turned on. This
could cause damage to the component or unit.
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, motor or blower, or
significant audio interference will result.
In all installations, use shielded cable exactly as shown, and ground as indicated .
Significant problems may result from not following these guidelines.
All audio installations can be seriously degraded by incorrect wiring and shielding, and
may result in abnormal cross-talk, hum and ground-loop noise. Be especially careful
with all microphone wiring and tie line wiring, as these lines carry the lowest level
signals in the aircraft.
The intercom tie lines should also be properly terminated with either the
appropriate number of additional units, or with a load resistor. See section
2.4.4, Tie Lines.
In all installations that use the Dynamic microphone capability of the N335,
extreme care must be taken with the shielding and routing of the microphone
wiring. This is especially true of the 5-ohm Dynamic mic input, where typical
signals are in the range of 100-
250 μ Vrms.
Special wire with Mumetal
shielding should be considered if there are any concerns about installation-
related noise.
Do not bundle the microphone wiring with high-level lines
(headphone, radio audio, coaxial cables, etc.).
Headset and/or helmet wiring may also need to be reviewed if using Dynamic
microphones. Many of the headsets and helmets on the market have minimal
shielding for the wiring associated with the mic and phone circuits. Those with
shielded wiring often use the Phone Lo connection for the shield ground. In the
N335, the Phone Lo connection is not ground referenced, so the shielding has
no effect. This will result in substantial coupling of the Phone signal onto the
Microphone wires, leading to high levels of crosstalk in the intercom system.
These shielding considerations also apply to in-line PTT cordsets. If a review
of the headset wiring indicates there will be a problem with the shield
termination, it is acceptable to ground the Phone Lo connection to a local
ground at the headset jack/connector.