Skanti TRP 9250, Technical Manual, Page: 141 / 289

TRANSCEIVER UNIT TU 9250
The Transceiver Unit in its basic version consists of a transceiver control module, a synthesizer
including master oscillator, a receiver/exciter module, a power amplifier module, a filter bank module
covering either marine frequencies only or the complete range 1,6 to 30 MHz, a power
supply/interface module, and a connection board. The main wiring is by ribbon cables with Micro
MaTch connectors on front of the ’plug-in’ modules. RF signals are routed in coaxial cables using
MCX connectors.
With the optional AC power supply assembly included, the equipment may be supplied from 115/230
V AC with automatic switch-over to 24 V DC supply in the absence of AC supply voltage. An optional
battery charger board enables the AC power supply to be used as a battery charger.
The transceiver unit may include one of five different DSC/telex options, either an interface board
enabling connection of an external modem to the transceiver unit, a telex modem, a DSC/telex
modem, the latter in connection with either a 2187.5 kHz single channel DSC watch receiver or a
scanning DSC watch receiver. The scanning receiver consists of two modules, a synthesizer and
a receiver signal path.
TU Control Board 910:
The digital part includes the micro controller, address decoder, program PROM, configuration
PROM, non volatile RAM, real time clock, ScanBus data communication driver, ATU interface, digital
TU-bus driver, remote interface and drivers for the analog circuits. The analog part includes voltage
regulators, analog interface circuits and analog output drivers. The TU Control Board performs the
digital and analog control of the transceiver functions requested by the control unit or the built-in or
external modem.
Synthesizer Board 911:
The synthesizer board includes synthesizers, dividing/multiplication circuits and check detectors.
The 1st, 2nd and 3rd local oscillator receive their reference signal from the master oscillator PCB
713.The 1. local oscillator covers the frequency range from 45 MHz to 75 MHz and generates the
injection signal for the 1. mixer on RX/EX signal path 715. The 2. local oscillator generates by
division and multiplication a 44.544 MHz signal for the 2. mixer. The 3. local oscillator generates a
456.5 kHz signal for the modulation/demodulation process.
Master Oscillator 713:
The master oscillator includes a highly stable Oven Controlled Crystal Oscillator (OCXO). The
master oscillator generates the accurate 17.8176 MHz reference signal for the synthesizers and
sets the 10 Hz frequency stability of the equipment.
RX / EX Signal Path 715:
The RX signal path includes protection, antenna attenuator, RF- and IF amplifiers, mixers, filter
bank, demodulator, squelch and audio line drivers. The RX signal path performs the handling of the
received antenna signal and delivers an AF signal to the control unit via DC Power Supply/Interface
TECHNICAL DESCRIPTION TRANSCEIVER UNIT TU 9250
4-4 TRP 9250 TECHNICAL MANUAL