题目内容

设中心频率为1MHz、频偏为50Hz的已调频波，调整为调频收音机所需的75kHz频偏的已调频波，中心频率为100MHz。下列步骤中不正确的是

A. 经15次倍频后，再经20次倍频，然后与310MHz混频后取差频；最后10次倍频
B. 经15次倍频后，与16MHz混频后取差频；然后100次倍频
C. 经1500次倍频后，与1600MHz混频后取差频
D. 经20次倍频后，与19MHz混频后取差频；然后75次倍频，与25MHz混频后取和频；

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