  We have investigated radio-frequency single-electron transistor (RF-SET)
operation of single-walled carbon nanotube quantum dots in the strong tunneling
regime. At 4.2 K and carrier frequency 754.2 MHz, we reach a charge sensitivity
of 2.3e-6 e/Hz^(1/2) over a bandwidth of 85 MHz. Our results indicate a
gain-bandwidth product of 3.7e13 Hz^(3/2)/e, which is by one order of magnitude
better than for typical RF-SETs.
