We are testing Agilent 8648C signal generator that will be used for NMR measurement. The output of the signal generator is connected to the transmission port of network analyzer (8714ET), and the transmitted power is being measured. We see 5 peaks at the signal frequency (31MHz) and the peaks are in 10kHz interval. We are puzzled by this. It seems that we are not doing the measurement right. How can we properly measure the output of the signal generator?