If I remember correctly, the 1PPS pulse width is only about 100 ns. There are two possibilities:
1) you can't see the pulse height properly at the very low sweep rate you're using. Trigger on it at a much higher sweep rate, crank up the intensity on your scope, and look carefully. 2) the output is dead. This happens occasionally. I had to replace the 74ac240 buffer in mine. Bill Ezell ---------- They said 'Windows or better' so I used Linux. Remco den Besten wrote: > I recently obtained a FEI FE-5680A Rb standard Revision: B. > > After powering it up 'out of the box', a lock @ 50.25505.. MHz was obtained > within > a few minutes, confirmed by measuring the lock indicator on pin 3 of J1 and > listening to the signal on my FT 857 receiver. Nice to hear it sweeping > before locking ;-) > Here te levels at pin3 of J1 are: unlocked +4V, locked +1.5V > > A 1PPS signal could not be detected with a multimeter, so I connected a > scope. > > I consider the signal levels somewhat peculiar and am curious if FE 5680A > owners > here have the same experience. E.g. the amplitude of the PPS signal at pin6 > is superimposed on a DC offset of ca. 170 mV and amounts (only?) 25 mV. > It is visible as a small spike here (depending upon the time base of > course). > My perception of a '1PPS' signal is a signal with TTL levels or open > collector out or something, and a pulse width of 10 - 200 ms.. > I connected a 2k2 resistor between pin6 and pin1 (pull up) but could not see > any improvement. The top-top amplitude remained ca. 25 mV. > > Pin6 (measured with scope) spikes with t = 1 sec: > > 200mV | | | > 170mV ------|------|------| > > The signal above will be hard to interface, but I feel that perhaps the PPS > output is not 'set' or perhaps broken. > > After powering up, the unit draws 1.6A which gradually decreases to 800mA. > This looks normal. > > Anyone any ideas? > > > > > > _______________________________________________ > 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.