Skanti TRP 9250, Technical Manual, Page: 142 / 289

Board 935 where the AF-signal is converted from an unbalanced to a balanced signal. The EX
signal path includes the AF compressor, modulator, filter bank, mixers and EX amplifier. The EX
signal path generates the modulated RF signal for the power amplifier. The RX / EX signal path is
controlled by the TU Control Board 910 and receives its injection signals from the Synthesizer Board
911.
Power Amplifier 721:
The Power Amplifier includes input attenuator, PA drivers, PA-stage, fan circuit, self protection, key
circuit and SWR detector. The Power Amplifier receives the modulated RF input signal from the
RX/EX Signal Path 715 and delivers the amplified output signal to the low-pass filters, PCB 726 or
727. The SWR detector output is a monitor signal for the TU Control Board 910. The fan circuit
drives the fan in accordance with the temperature signal monitored on the Power Amplifier and the
DC power supply/Interface Board 935.
Marine Filters 726 / Continuous Filters 727:
The PA filters includes low-pass filters, relay drivers and a peak detector. The PA Filters removes
the unwanted harmonic frequencies from the PA signal received from the Power Amplifier. The
output of the PA Filters is connected to the input of the ATU via RX/TX Relay on the DC power
supply/Interface Board 935. The selection of low-pass filter is controlled by the TU Control Board
910. The Peak Detector monitors the output power and the Peak Detector output is used for power
level adjustments and for displaying the power level in the control unit.
Marine filters 726 covers the frequency ranges
1.6 - 4.8 MHz
6.2 - 8.95 MHz
12.23 - 17.65 kHz
18.78 - 27.1 kHz
Continuous Filters 727 covers the frequency range 1.6 - 30 MHz
DC Power Supply/Interface Board 935:
The DC switched mode power supply generates all internal the voltages needed in the equipment
galvanically isolated from the battery, only the Power amplifier is supplied directly from the battery.
The SMPS is switched on from the control unit via the Scanbus SUPPLY ON wire and switched off
under software control via the SUPPLY ON/OFF connection from the TU Control Board or the PCP
Board 717. A protection circuit switches the SMPS off in the event of an output overload and switches
on again when the overload condition has been removed. The DC supply voltage is sensed by a
BAT INFO detector circuit and fed to the TU Control Board for automatic RF output power
adjustment.
TRANSCEIVER UNIT TU 9250 TECHNICAL DESCRIPTION
TRP 9250 TECHNICAL MANUAL 4-5