NGT—Technical description (2010)
70 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 bus, junction box and CIB to the Audio
Interface PCB in the RF unit.
PWR ON from the CIB switches V2 on and energises the latching relay coil K1. This
closes contacts K1/C and K1/D resulting in the PWR ON line to the PA PCB being
grounded.
The PWR ON line goes to the power relay coil K200. If the polarity of the DC supply is
correct and below 16 V, V218 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 V217 to also
conduct and switch off V218, 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.
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.
Drawing 04-03125 and 04-03201, or
Drawing 04-03125 and 04-03423
Drawing 04-03109
ALTERNATIVE TEXT
Drawing 04-03169
ALTERNATIVE TEXT
Drawing 04-03369, or
Drawing 04-03542
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