Rohde & Schwarz M3SR Series 4100, Service Manual, Page: 41 / 138

Function R&S M3SR Series 4100 HF Transceivers
1.5 6124.9007.82.01
In transmit mode, the digital IF-data (complex I/Q) is converted in the Frontend module to an analog
48 kHz signal. This is mixed to the 48.048 MHz intermediate frequency and the commanded transmit
frequency. The transmit signal of +10 dBm is taken from X1 of the Frontend module to X311 of the
Power Amplifier. The transmit signal can be routed through a R&S FK 4120 / R&S FK 4140 Digital
Selector if one is connected to X313 and X314. The modulated transmit signal is amplified and filtered
(harmonic filter) in the Power Amplifier and finally made available at antenna connector X30.
The Synthesizer generates the LO1 and LO2 signals needed in the Frontend module. The LO1 signal
(40.058 to 70.048 MHz) at X101 is used for upconverting the antenna signal into the 1st IF. The LO2
signal (80 MHz) at X102 is used for downconverting the 1st IF signal into the 2nd IF.