In a message dated 6/9/2007 08:26:06 Pacific Daylight Time, [EMAIL PROTECTED] writes:
>Many of us have 5370; can you describe exactly the setup >you're using so we can make apples-apples comparisons. >What source, what cable, what connectors, switch settings, >int/ext ref, etc. >/tvb Hi Tom, this was the recommended setup (by HP) for checking the internal noise. Feed the 10MHz output back to the input using a short cable, and set the unit for "COMMON" input, setting 50 Ohm impedance etc. In the meantime I did some more tests, and found the following: 1) The sine-wave output is crappy. The sine wave has some sort of "Class-B" cross-over distortion, and it measures a whooping 200ps RMS jitter on my Wavecrest jitter analyzer (>400ps pk-pk). Compare that to 2.7ps RMS jitter I measure on our Fury 10MHz output. Definitely the crystal got damaged, or something else. The unit has about 2x better jitter performance (around 50ps RMS) if I feed a clean Fury 10MHz into it. I think the 10811 OCXO or the internal driver circuit may have gotten damaged. 2) As described earlier, with the Fury GPSDO driving the unit's ref input, and very careful adjustment of the trigger level I can get RMS readings <30ps with good time-intervall output. This is on a setup as follows: REF-IN driven by Fury unit A 10 MHz output One input driven by second Fury unit B 10MHz output Second input driven by PRS10 GPSDO 10MHz output Unit set to measure +-Time Intervall I am happy with that result, except the trigger pot sensitivity, it's very hard to set correctly, and sometimes jumps to >60ps RMS by itself. I hope to be able to replace the 10811 - although feeding it externally is not a bad idea, and hopefully get the full <30ps performance in "preset" mode after full calibration. Has anyone had similar problems? thanks, bye, Said ************************************** See what's free at http://www.aol.com. _______________________________________________ time-nuts mailing list [email protected] https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
