Time Nuts: I have a few Austron 1250As. One of them has an ADEV with a large hump at around 50 secs time scale (2E-11). Using a 53230A counter, I can convince myself that I can see the frequency go up and down at around that period. I guess that this is an oscillation in the oven circuits.Anyone have an idea whether this is curable and how? Thanks! Jim

Hi Typically when you have an oven go into long period oscillation, you can see the current “cycle” as it does so. It usually is not a subtle thing. It also typically creates a bigger hump than you are seeing. The usual cause for this happening is a high resistance in the feed wiring to the part. A bum bandanna plug or busted wire often are the root cause. Could it be the oven circuit? Sure it could, however it’s likely doing something pretty subtle. Bob > On Aug 7, 2024, at 10:55 PM, AC0XU (Jim) via time-nuts <time-nuts@lists.febo.com> wrote: > > Time Nuts: > > I have a few Austron 1250As. One of them has an ADEV with a large hump at around 50 secs time scale (2E-11). Using a 53230A counter, I can convince myself that I can see the frequency go up and down at around that period. > > I guess that this is an oscillation in the oven circuits.Anyone have an idea whether this is curable and how? > > Thanks! > Jim > _______________________________________________ > time-nuts mailing list -- time-nuts@lists.febo.com > To unsubscribe send an email to time-nuts-leave@lists.febo.com

Hi Jim, There is really two paths into your measurements which can cause this: 1) Some form of environment (which include oven oscillation itself) modulation the oscillator frequency 2) Some form of environment modulating the counter measurement One approach is to measure voltage, current, temperature etc. to see if any of that correlates. I've myself found a highly unstable oven, and the tell-tale was an ADEV bump at 3 s, which is not where we expect one. I then was able to see it on the PSU current, and power-cycling the output triggered a HUGE ring that rang out to a remaining oscillation. The oscillator vendor investigated the sample I gave back to them, and they learned the hard way they made a mistake. They reported it just fine, but their salesman missed by saying "it meets specs" which I replied "I still can't use it". So, it can very well be that. Sometimes the exact condition for the OCXO can make it get similar missbehaviours. There is also things in reference and counter that can mess with you in similar way. Trying different setups to rule out where it happens can help. Sometimes a bad trigger-point can be the culprit. Guess how I know... Happy hunting! You learn a lot from doing that. Cheers, Magnus On 2024-08-08 04:55, AC0XU (Jim) via time-nuts wrote: > Time Nuts: > > I have a few Austron 1250As. One of them has an ADEV with a large hump at around 50 secs time scale (2E-11). Using a 53230A counter, I can convince myself that I can see the frequency go up and down at around that period. > > I guess that this is an oscillation in the oven circuits.Anyone have an idea whether this is curable and how? > > Thanks! > Jim > _______________________________________________ > time-nuts mailing list -- time-nuts@lists.febo.com > To unsubscribe send an email to time-nuts-leave@lists.febo.com