A tower mounted amplifier and a filter. The filter includes a transmission part having a first tunable portion and a reception part having a second tunable portion and a third tunable portion. The transmission part is coupled between a first port and a second port. The second tunable portion of the reception part is coupled between the first port and a third port, and the third tunable portion of the reception part is coupled between a fourth port and the second port. The first tunable portion is configured to work in a first frequency range different from a first pass band in which the second and third tunable portions are controlled to work when a radio frequency signal is to be transmitted from the first port to the second port, the radio frequency signal being rejected by the first tunable portion to the second port.