Northern Airborne Technology 211 - Manual (Page 13)

Model 211 Voice Activated Switch
SM211 Installation and Operation Manual
Section 2 Rev: 1.00 Issue 2 Page 2-3
ENG-FORM: 805-0115.DOT
CONFIDENTIAL AND PROPRIETARY TO NORTHERN AIRBORNE TECHNOLOGY LTD.
2.4.5.1 Voltage/Resistance Checks
Do not attach the Model 211 until the following conditions are met.
Check the following:
a) Check pin <7> for +28 Vdc relative to ground.
b) Check pin <9> for chassis ground (less than 0.5 Ω).
2.4.5.2 Power On Checks
WARNING:
High volume settings can cause hearing damage.
Set the headset volume control to the minimum volume setting prior to
conducting audio tests, and slowly increase the headset volume to a
comfortable listening level.
Power up the aircraft’s systems and verify normal operation of all functions of the model 211.
Upon satisfactory completion of all performance checks, make all required log book entries, electrical
load, weight and balance amendments and other documentation as required by your local regulatory
agency before releasing the aircraft for service.
2.5 Adjustments and Connections
2.5.1 Squelch Level Adjustments
2.5.1.1 External Adjustment
If a remote potentiometer is installed, the model 211 internal adjustment should be turned completely
clockwise (cw), and pin 5 should be connected to a remote 10 kOhm ¼ watt (minimum) variable resistor.
This will allow the squelch to be adjusted from 40 to 350 mVrms.
2.5.1.2 Internal Adjustment
If a remote switch is not to be used, a jumper should be installed across pins 5 and 8. Rotating the
internal potentiometer completely counterclockwise (ccw) will adjust the squelch from 16 mVrms minimum
to a maximum of 350 mVrms when completely cw.
2.5.2 Pin Identification
The model 211 Connection diagram is found on the 211 Outline drawing in Section 2.7 of this manual.