Robert Lutwak wrote: >I suspect you're just measuring the bandwidth of your 400 MHz oscilloscope. > > > Usually the expected rise time for a 400MHz oscilloscope would be 0.35/bandwidth = 0.875ns, so although the scope bandwidth is limiting the measuremens, seems that the 74ACT04 is a bit slower than the scope :) Regards, Javier, EA1CRB