Northern Airborne Technology 270 - Manual (Page 12)

Model 270 Universal Interface Amplifier Manual SM270 Rev. 4.10
1.4.1.2
Input Specifications
INPUT DESCRIPTION
Audio Input
Channel
(receiver audio)
One differential receiver/transceiver audio input. Input range is
0.5 Vrms to 7.75 Vrms. A 10 K
Ω termination resistor to ground
is provided on the HI and LO side of the receiver input pins and
a 1 K
Ω resistance is connected between the HI and LO inputs.
Equivalent input impedance is approximately 600 Ω.
MIC Input Channel 0.25 Vrms into 200 Ω nominal. Dynamic range from 20 mVrms
to 1.5 Vrms. DC Bias is 9 Vdc @ 20-25 mA.
SPARE Input
Channel 0.25 Vrms into 200 Ω nominal. Dynamic range from 20 mVrms
to 1.5 Vrms. DC Bias is 9 Vdc @ 20-25mA. VOX switch
activation is within 5 mS of speech detection and deactivation 2
seconds after speech. VOX range is 20 mVrms to 250 mVrms.
28V Circuit Power
Supply 28 Vdc power to operate the internal circuitry is connected to this
pin. Power Supply range is 18 Vdc to 32 Vdc, 0.05A nominal,
0.25A Max. (use 0.5A circuit breaker). Use 22 AWG wire min.
14V Circuit Power
Supply 14 Vdc power to operate the internal circuitry is connected to this
pin. Power Supply range is 9 Vdc to 15 Vdc, 0.05A nominal,
0.25 A Max. (use 0.5A circuit breaker). Use 22 AWG wire min.
Power Return (Gnd) Use 22 AWG wire min.
Chassis Ground
Ground chassis directly to airframe or with a suitable ground
strap.
1.4.1.3 Output Specifications
OUTPUT DESCRIPTION
Audio Output
Channel
A transformer coupled output capable of driving loads ranging
from 8
Ω to greater than 600 Ω. Maximum rated output level is
8 Vrms (106 mW) into 600 Ω or 0.70 Vrms (60 mW) into 8 Ω.
Output is adjustable.
MIC Output
Channel A transformer coupled output capable of driving loads ranging
from 8
Ω to greater than 600 Ω. Maximum rated output level is
8 Vrms (106 mW) into 600 Ω or 0.70 Vrms (60 mW) into 8 Ω.
Output is adjustable. An internal installer selectable jumper can
be removed to connect a 1
µF series capacitor to provide AC
coupling of the output transformer secondary. Maximum load
when the jumper is removed should not be less than 600
Ω.
Spare Output
Channel A single ended (ground referenced) microphone level audio output
capable of driving loads ranging from 150
Ω to greater than 600 Ω. The
Spare Output is fed by the Spare Input channel and is switched by the
Voice Activated Switch circuit. Output level is 0.25 Vrms into 150
Ω.
Page 1-4 Dec 12, 2006
ENG-FORM: 800-0108.DOT
CONFIDENTIAL AND PROPRIETARY TO NORTHERN AIRBORNE TECHNOLOGY LTD.