Hi Hal, I think its a slow driver, and a complex output impedance, not necessarily a weak driver.
I have a Tbolt hidden somewhere and would need to dig it out. My 30 foot cable disappeared though, so I need to buy a new one :( On the small hump, i don't think that is a reflection. The signal risetime is just too slow to create such fast spurts. I think it may be a capacitor bridging a larger series resistor. Yuck. Oh, on the z3801 I thought it had a bnc 1pps output as well.. Bye, Said Sent From iPhone > On Sep 16, 2014, at 13:07, Hal Murray <[email protected]> wrote: > > > [email protected] said: >> here are some plots from two GPSDOs, one series terminated (CSAC GPSDO), >> and one load-terminated (Agilent 58503A) product. > > Nice pictures. Thanks. > > My reading of your pictures is that the 58503A has a weak driver. Do you > have a TBolt? > >> ... and there is a little hump right at the beginning. > > That could be a reflection from an impedance change. I wonder what's inside > the box. > > >> I don't know what the output circuit of the 58503A looks like, but >> assuming that it probably is the same as on the Z3801 units many folks here >> have it is quite relevant to this discussion, and comparing these two >> approaches really shows the quality difference between these two products' >> signals. > > The Z3801 doesn't have a simple BNC connector for the PPS. Their are 2 pairs > of differential PECL signals on the DB-25. I haven't looked at them. > > If all you want to do with the PPS is feed it to NTP, you don't need ns level > accuracy. There is a standard recipe for converting the RS-422 levels to > RS-232 and borrowing one of the drivers for the PPS signal. RS-232 drivers > are deliberately slow enough to avoid most of these problems. > > The 10 MHz comes out on a BNC. That's what most hams use for multiplying up > to GHz. > > > -- > These are my opinions. I hate spam. > > > > _______________________________________________ > time-nuts mailing list -- [email protected] > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
