The bandwidth advancement of a Ka-band, conventional three-cavity gyroklystron amplifier using clustered-cavity approach has been explained in detail. The strong consequence of varying the location of clustered buncher cavity on the RF out power, gain, efficiency, and bandwidth has also been studied in detail. It has been observed that the maximum efficiency has been achieved when the clustered buncher cavity is located nearer to the output cavity whereas highest gain is obtained when the clustered buncher cavity is located in between the input and output cavities.