  We have analyzed the response and noise-limited sensitivity of the
radio-frequency single-electron transistor (RF-SET), extending the previously
developed theory to the case of arbitrary large quality factor Q of the RF-SET
tank circuit. It is shown that while the RF-SET response reaches the maximum at
Q roughly corresponding to the impedance matching condition, the RF-SET
sensitivity monotonically worsens with the increase of Q. Also, we propose a
novel operation mode of the RF-SET, in which an overtone of the incident rf
wave is in resonance with the tank circuit.
