Rev B
Page 1
JA39-075 Low Impedance Headset Adapter -
75Ω Mic
-
150Ω Phones
SECTION 1 - DESCRIPTION
1.1
System Overview
The JA39-075 Low Impedance Headset Adapter - 75 Ohm Mic - 150 Ohm Phones allows a low impedance headset to
be used with a civilian aviation audio controller. The JA39-075 operates using the microphone bias supply of the audio
controller and requires no other external power. The phones audio from the audio controller is routed directly through
to the Headphone.
The JA39-075 is a simple plug and play solution that uses the microphone bias provided by the audio system to
amplify the Low Impedance Mic Signal to an appropriate level, and matches the headset impedance via transformer.
1.2
Features Overview
The JA39-075 features one male and one female TJ-120 telephone jack and follows industry standard interconnect
for aviation headsets.
The JA39-075 unit features an industry standard headset pin-out to allow plug and play operation.
The JA39-075 plugs in-line with the headset cord.
The JA39-075 uses a metal enclosure to shield the circuitry from Radio Frequency Interference.
1.3
Inputs and Outputs
Refer to the JA39-075 connector maps for the mating connector designators and pin assignments for the
input and output signals.
1.3.1
Inputs
Name
Qty Type
MIC INPUT HI/LO
2
Audio signal
PHONES INPUT HI/LO
2
Audio signal
1.3.2
Outputs
Name
Qty
Type
MIC OUPUT HI/LO
2
Audio signal
PHONES OUPUT HI/LO
2
Audio signal
1.3.3
Mic Bias Voltage Supply
The Microphone Output accepts a DC MIC INPUT bias voltage supply from the Audio Controller.
