SRK Electronics MFTX100, Руководство по эксплуатации и обслуживанию, Страница: 65 / 100

MFTX AM TRANSMITTERS
SRK Electronics 65
The outputs of the RF amplifiers are summed in a transformer based combiner.
The output from the combiner is passed to the output filter assembly. This
consists of a lumped constant low pass filter, followed by a directional coupler.
The directional coupler generates a sample of the forward and reflected RF
voltages which are used by the control unit to monitor forward and reflected
output powers.
A spark gap and RF sample port are also included in the output filter assembly.
Audio processing, RF generation, remote control, metering, protection and front
panel interface is provided by the controller unit.
Audio is processed in the analogue domain, with gain control, compression,
limiting and filtering performed by circuitry within the control unit. Processed
audio is then passed the RF generator module.
The RF generator module is a proprietary unit that performs advanced amplitude-
to-phase conversion in the digital domain. The output of the RF generator
consists of two squarewaves at the carrier frequency (RF+ and RF-). The
relative phase of these squarewaves sets the instantaneous RF voltage at the
output of the transmitter.