Comtech EF Data CST-5000 - Manual (Page 110)

CST-5000 C-Band Satellite Terminal Theory of Operation
Rev. 9 5–21
5.6.2 Theory of Operation
The RFT-500 up converter utilizes a dual conversion process to convert from a baseband
70 MHz IF signal to the output RF frequency band.
The first conversion requires an IFLO frequency input at 1060 MHz from the IFLO
module. The output of the first mixing process is at a frequency of 1130 MHz.
The 1130 MHz output is applied to the second mixer which mixes with the synthesizer
frequency input. The up converter synthesizer output frequency band is from 4715 to
5295 MHz, in 2.5 MHz steps (optional 125 kHz steps). The M&C board controls the
frequency selection of the synthesizer.
The output of the second mixer is the desired RF frequency band of 5845 to 6425 MHz.
The M&C board interpolates the factory preset compensation data that is stored in an
EEPROM inside the up converter. This data allows the M&C board to command and
compensate the up converter’s output power, ensuring proper output power levels over
the entire frequency and temperature range.
The M&C also controls the up converter attenuator.