To reduce transmitter pull-in setting by attenuating a reception disturbing frequency equal to a transmission frequency when the transmission frequency is the fraction or multiple of the desired reception frequency.
When receiving the effective frequency of 2003 MHz, for example, a control unit SE controls an AGC circuit so that a correspondent effective signal can be supplied through a selection step to a mixer M. Further, the control unit SE controls a frequency divider or multiplier block MT through a broken line so as to operate it as a multiplier. Thus, in the case of transmission frequency of 1000 MHz, the input frequency of 2003 MHz is supplied to one terminal of the mixer and the frequency of 2000 MHz is supplied to the other terminal by double multiplication. In this case, the selection is controlled by the control unit SE so that the correspondent interference frequency of 1001 MHz, for example, possible to be generated can not reach the transmitter frequency of 1000 MHz.
CLEMENS KLAUS