 The synthesizer is used for developing all the signals used by the transmitter and receiver.

 It uses the PLL circuits and a mixer.

 The crystal oscillator provides a reference for the two PLLs.

 The output of VCO-2 is used as a local oscillator frequency for the first mixer in the receiver.

 The outputs of the two VCOs are mixed together to produce the transmitter output frequency.

 The frequency divider block receives the divide by numbers from the logic section.

 These numbers are given by the MTSO computer.

 The divide by numbers will set the transmitting and receiving channel frequencies.

 The two outputs produced by the frequency synthesizer are applied to the modulator box in the transmitter and the first mixer in receiver respectively.

 Thus the frequency synthesizer acts a local oscillator which can produce a wide range of frequencies with high stability