Try setting your scope to a relatively slow speed, 50 mSec/cm or so, set it to trigger on the appropriate channel, positive slope, turn off 'Auto' trigger thus just getting a sweep only if triggered, then adjust the trigger sensitivity to see if you see a sweep go across the screen once per second. If so, turn the intensity up very high and move the sweep speed to 1 uSec/cm and look very closely at the very first part of the trace, about 5 V above the base line. Should be a 1 uSec wide pulse across the screen only once per second (thus the need to turn up the intensity of the display).
I used a 10X probe on pin 6 to measure this (10 Meg Input Impedance). Hope this helps. Joe -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of Joseph Gray Sent: Wednesday, January 11, 2012 12:11 AM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] FE-5680A arrived I'm not seeing a PPS on either of these. All I see is about 17 mV P-P of noise that looks like a multi-stepped sine wave. I'm using a TDS 340 scope. Joe Gray W5JG On Tue, Jan 10, 2012 at 10:30 PM, J. L. Trantham <[email protected]> wrote: > I confess! > > I, too, could not resist the opportunity to 'commune' with the members > of the list with these Rb units. > > I ordered two of the FE-5680A units ($36 ea. including shipping) from > the same supplier with amazing speed (order date 1/4, arrival date 1/9 > to NW Florida). > > They were marked 'FE-5680A UN 70021' 'S/N 0405-72179' and 'FE-5680A UN > 71920' 'S/N 0413-75933'. > > I promptly came home, constructed a DB9 female connector, with the > connections as specified in recent postings, and both units were up > and locked with extremely close agreement with my TBolt and Z3816A in > under 5 minutes. Pin 6 had a 1 uSec wide, 5 Volt, 1 PPS, pulse. I > did not explore pins 8 or 9, the RS232 pins. I guess I'll have to go > back through the list to see what, exactly, I can do with these. > > They, too, were packed with bubble wrap individually and then > together, and in a plain envelope that was placed in a UPS plastic > envelope. However, they arrived without damage, and, amazingly, very > promptly. > > Not sure what, exactly, I will do with them yet, but they will > certainly have many possible roles. > > Joe > WB4BPP > > > > -----Original Message----- > From: [email protected] [mailto:[email protected]] > On Behalf Of Joseph Gray > Sent: Tuesday, January 10, 2012 8:04 PM > To: Discussion of precise time and frequency measurement > Subject: [time-nuts] FE-5680A arrived > > With all the talk on the list about these things, and considering the > price, I could no longer resist temptation and ordered two from > nichegeek. > > First, I was amazed at the speed at which I received these units. The > order was placed last Friday, the shipment went out late Saturday and > I received them today (Tuesday). In my experience, it has always taken > two weeks or more to receive anything from China. I couldn't believe I > got these in just three days. > > BTW, I paid $38 each with the free shipping. An outstanding deal IMO. > I also received the semi-useless freebies. > > My only quibble so far is that both units were packed in nothing more > than a large envelope, with a thin layer of bubble wrap added. Nothing > is dented or rattling around, so hopefully they are OK. I'm just about > to wire up a cable and power them on, so I'll know soon. > > The units I got have numbers of UN 71xxx and UN 78xxx. I don't know > exactly what this means, but according to the ebay sellers, they are > claiming that 6xxxx and 7xxxx numbers indicate newer units. Can anyone > decipher this number sequence? > > Joe Gray > W5JG > > _______________________________________________ > 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. > _______________________________________________ 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.
