NGT—Technical description (2011/2012)
104 NGT Transceiver System Technical Service Manual
Power on
If the transceiver is off when the key is pressed, the +5.4 V standby voltage is applied
to gate V9 resulting in the drain going low.
The PWR ON line passes via the handset cable to the Audio & Interconnect PCB
(2011)/Audio Interconnect & Data I/O PCB (2012) in the RF unit.
Control for the power relay on the PA PCB, which in turn controls the transceiver power,
is via latching relay K1. This relay is activated by pressing the key on the handset,
which grounds the PWR ON line in the handset, setting relay K1 via transistor V1.
The PWR ON line goes to the power relay coil K200. If the polarity of the DC supply is
correct and below 16 V, V216 conducts and relay K200 energises, thus closing contacts
of K200 and connecting the DC supply to the transceiver.
If the DC supply voltage exceeds 16 V, zener diode D203 conducts, causing V215 to also
conduct and switch off V216, thus preventing K200 from energising.
Diode D205 prevents relay K200 from operating if the DC supply is reverse polarised.
The power input circuit is protected from high voltage transients by the voltage-
dependent resistor R261.
Drawings 04-03125
2011: Drawing 04-03425
2012: Drawing 04-03499 (sheet 1) and 04-03499 (sheet 2)
Drawing 04-03369, or
Drawing 04-03542
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