NGT—Technical description (2011/2012)
NGT Transceiver System Technical Service Manual 109
Transmit path
Handset microphone amplifier transmit path
The handset has an electret microphone. When PTT is not pressed, the microphone audio
is clamped by V5.
When PTT is pressed, V5 is turned off, allowing audio from the microphone to be passed
to the amplifier IC9/B. The output of IC9/B is split into two paths, one going to the
handset audio bus, the other passing through the inverter IC9/A before going to the
handset audio bus. In this way, push-pull balanced audio is provided to the handset bus.
RF unit—Audio & Interconnect PCB (2011)/Audio Interconnect & Data
I/O PCB (2012) transmit path
Tx audio
The balanced microphone audio from the handset is filtered in L2, then converted to a
single-ended signal in IC2/A. It then passes via the Application Processor Handset I/F
3 V PCB (2011)/Application Processor Handset & Data I/F PCB (2012), which provides
the microphone compression, through the analog switch IC5 to the RF/IF PCB Tx audio
path.
Drawing 04-03125
2011: Drawing 04-03425
2012: Drawing 04-03499 (sheet 1) and 04-03499 (sheet 2)
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