Jason Rabel wrote: >> Jason, >> >> The only problem with that part is that it's not a buffer! It's a >> switch. It has no drive capability at all. >> >> There are useful buffer chips for this task, but their names escape me >> just now. Perhaps the 74FCT245 or equivalent would work. >> >> Driving a full 5V TTL signal into a 50 ohm load is another matter - you >> need a lot of DC power (1/2 watt) to do that. I was just using a Liner >> Tech LT1010 for a similar job - it would get the job done, but folks >> here might complain about the phase noise. >> > > You're right... I guess I had a brain fart, I don't know where my mind was > at that moment... ;) > > Anyhow, besides using a buffer chip (like the several mentioned in other > posts), how would using a plain old voltage following op-amp compare? I > haven't looked up any specs yet, I'm just throwing the idea out there. > > > _______________________________________________ > time-nuts mailing list > time-nuts@febo.com > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > > Unless you use a wideband opamp the transition times will be inferior to those achieved with a relatively inexpensive logic gate such as a 74AC540 or equivalent. Depending on the opamp output stage you may also need a negative supply to ensure that the opamp output will actually reach zero volts. To ensure stability it may be necessary to use a small resistor in series with the opamp output, in which case you may as well use this resistor to match the line impedance.
Bruce _______________________________________________ time-nuts mailing list time-nuts@febo.com https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts