Hi guys, has anyone seen phase jumps of the "nanoseconds" range without any affect to the picosecond display in the 5370B before? This problem has been appearing before I ever opened the unit, so it's not related to my calibration/mods. What is happening is really weird: Whenever the unit reacheas about 13.5ns TI A-to-B input difference (in +-TI mode), the output measurement jumps around in complete nanosecond changes. The picosecond range display is not affected by this!! The unit is in 100-samples averaging mode, set up to "TALK" mode on the GPIB. The attachement is a zoomed-in version of the longer-term measurement sent out in the previous email. Scale is about 12.8ns to 14.35ns. The LED Display can be seen to jump around when this happens, but only the nanosecond digits(!) the three picosecond digits remain stable with little noise such as:
13.543 13.545 13.547 11.549 9.547 14.548 10.548 11.550 etc. This seems to me to be a digital problem, maybe in the averaging algorithm? Maybe because the unit is in GPIB talk-only mode with the GPIB-to-RS232 converter attached? Maybe it's an "anti-coincidence" calibration issue? In the attached PDF you can see it jump back and forth by about 1 or 2 nanoseconds. I have seen it jump 5 or more nanoseconds as described above. It happens (repeatably) at around 13.5 nanoseconds. Has anyone seen this as well? thanks in advance, Bye, Said ************************************** See what's free at http://www.aol.com.
5370b_noise_zoom.pdf
Description: Adobe PDF document
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