I think there is something funny about the 1 PPS output on pin 6 from the currently available cheap FE-5680A units. I have three of these units. On one unit, on one occasion, I did observe a logic-level 1 PPS pulse, exactly 1 microsecond wide. But after a power cycle it never came back, although the unit indicates a locked condition, and is apparently working. The other two units also seem to work (10 MHz output OK, lock OK) but I have never seen a 1 PPS signal on pin 6 from them. My Tek TDS-210 is easily capable of triggering on and displaying a 1 usec pulse. Is it possible the pulse appears only after a RS-232 command, or after some other special condition?
> -------Original Message------- > From: David <davidwh...@gmail.com> > To: Discussion of precise time and frequency measurement <time-nuts@febo.com> > Subject: Re: [time-nuts] FE-5680A performance > Sent: 05 Jan '12 07:49 > > On Thu, 05 Jan 2012 01:44:13 -0800, Hal Murray > <hmur...@megapathdsl.net> wrote: > > >albertson.ch...@gmail.com said: > >> > >> Have an older Tek 465 scope that is in only "fair" shape and I see nothing > >> on that pin but milivolt level sine wave of about 60MHz. I can't set the > >> scope to show any hint of a PPS ... > > > >I do have a 465. You should be able to see a 1 uSec PPS. > > 60MHz is about a 6nS rise time and is easily fast enough to see it. > > >Now turn up the Intensity until you can see the pulse. It might help to > turn > >down the room lights. > > This is the problem. With a 1 second repetition rate, the brightness > is going to be very low. > > The old ways of viewing such a low repetition rate signal include > using a hood or dark room, special CRT phosphors, photographic film, > MCP (micro channel plate) intensified CRTs, and of course analog > storage and later digital storage. > > _______________________________________________ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. > _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.