Model 240 Passenger Speaker Amplifier
SM240 Installation and Operation Manual
Section 1 Rev: 1.00
Issue 4
Page 1-2
ENG-FORM: 800-0114.DOT
CONFIDENTIAL AND PROPRIETARY TO NORTHERN AIRBORNE TECHNOLOGY LTD.
Stereo Left:
One single, switched differential audio input from the Left channel of
the stereo audio from a stereo receiver/ music source. Input level is
maximum 1.00 Vrms (at max. source volume) and audio LO is not
common to that of other inputs.
Stereo Right:
One single, switched differential audio input from the Right channel
of the stereo audio from a stereo receiver/music source. Input level is
maximum 1.00 Vrms (at max. source volume) and audio LO is not
common to that of other inputs.
Briefer:
One single, switched audio input from Briefer audio, etc. Input level
is 1.00 Vrms
PA MIC:
The microphone input, used for Cabin Paging audio, supplies bias
current and is compatible with carbon and amplified dynamic
microphones.
Paging Volume:
Controls the level of PA MIC and Briefer audio inputs to the PA
Sidetone and Left and Right Speaker outputs. Volume control range
is 30 dB (minimum) controlled by a 10 kOhm ½ watt, linear
potentiometer. When the potentiometer is at maximum, the level is at
maximum.
Receiver Volume:
Controls level of ADF, PSC and TV audio inputs to the Left and Right
Speaker outputs. Range and control same as Paging Volume
specification.
Power Supply:
28 Vdc, 3A maximum.
Output Signals:
Left/Right Speaker:
The Left and Right Speaker Amplifier output ratings are each
20 watts into 2 Ohms. This is a peak rating, intended for speech and
music. The continuous rating of the amplifier output is 2 watts into
2 Ohms for sine wave operation. Power ratings are as follows:
Load
Rated Power
Continuous Power
2 Ohm
20 W
2W
4 Ohm
10 W
1W
PA Sidetone:
This output will deliver 6.7 mW into 600 Ohms continuously. Rated
and continuous power ratings are the same.
Chime Tone:
Generated and supplied to Left and Right Speaker outputs when 12 to 32
Vdc is applied to and removed from connector pins P50-31 and P50-32.
Provides a 790
±
20 Hz tone, followed by a decaying 610
±
20 Hz tone.
Factory set for 3.5 VP-P into 2 Ohms, adjustable from 1.0 to 6.9 VP-P.
Ringer Tone:
Generated and supplied to Left and Right Speaker outputs when a
ground signal is applied to connector pin P50-33. 700
±
75 Hz tone,
ON for 1.8
±
0.1 seconds, then OFF for 3.2
±
0.1 seconds, repeating.
Factory set for 1.5 VP-P (700 Hz component) into 2 Ohms,
adjustable from 0 to 5.2 VP-P.
Frequency Response:
Stereo inputs to Speaker outputs – Flat within 3 dB from 85 Hz to
20,000 Hz. All other inputs to Speaker or PA Sidetone outputs – Flat
within 3 dB from 350 Hz to 6,000 Hz.
Harmonic Distortion:
Less than 3 percent distortion, all outputs.
Isolation Between Channels: 60 dB, minimum.
Output Noise:
Greater than 75dB below rated, all outputs.
