Sailor RT2047 Technical Manual - page 47
2 CIRCUIT DESCRIPTION
RT2047 DSC - PART II
2.4
TX-POWER AMPLIFIER MODULE 400
The TX-power-amplifier includes the amplifier and a harmonic filter.
2.4.1
TX-POWER-AMPLIFIER
The amplifier consists of a single transistor output amplifier and a two transistor power driver. The
transistors are both tuned classic amplifier circuits. The amplifier is made on double sided epoxy board,
using micro strip technique in the tuning circuits. The power driver is fed from a 50 ohm generator with
a power level of 25 mW. The final output power level is controlled by means of the supply voltage level
fed to the power driver. In full power mode, the power driver will deliver about 4.5 - 5 W to the output
transistor T401. The output signal is fed to the harmonic filter through capacitors C405 and C406.
2.4.2
HARMONIC FILTER
The harmonic filter is realised as a seventh-order Chebyschev-filter, which at the same time will provide
the necessary attenuation of the harmonics generated by the power amplifier and a low insertion loss at
the carrier frequency. The output from the harmonic filter is fed to the antenna relay.
2.5
ANTENNA RELAY (500)
The antenna relay, RE501, is placed in the Tx-power amplifier module (400).
The relay is equipped with 2 change-over contacts and is activated when the transmitter is keyed.
In simplex receiving mode the RF signal is led to the receiver (100) through both contacts from the Tx-
section of the duplex filter.
In simplex or duplex transmitting mode the Tx-signal is led from the harmonic filter through a pin to the
Tx-section of the duplex filter.
The other pin is grounded.
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