Hi Having run a 5071A with a *very* good 10811 in it, the OCXO does dictate what happens at 0.1 seconds. Once you get past that, you are headed into a bit of a gray zone. You are partly looking at the Cs and partly looking at the OCXO. Pushing out the crossover between the two could help you at 1 second. The gotcha is that the “hump” will still be there, just a bit further out. The net effect at (say) 100 seconds could easily be worse with the “fix”.
Bob > On May 27, 2017, at 8:15 PM, Richard (Rick) Karlquist <rich...@karlquist.com> > wrote: > > On 5/27/2017 2:08 PM, Donald E. Pauly wrote: > >> I am investigating the total redesign of the HP5061B lock system for >> vastly improved performance. It looks like the performance of the >> HP5071A can be beaten by 10 to 1 for averaging times on the order of a >> few seconds. >> πθ°μΩω±√·Γλ >> WB0KV > > That's an interesting claim, but it could be valid. > The 5071A flywheel is a 10811 selected for performance > and modified to have additional electronic tuning > range (I was involved in that) but otherwise it is > plain vanilla 10811. At a few seconds averaging time, > this oscillator is basically open loop. It might be > possible to improve a 5071A by simply finding a 10811 > with exceptional short term stability. The tail of > the distribution curve went down at least an order of > magnitude, according to Jack Kusters at HP. > > In any event, you could use an unmodified 5071A or maybe > a 5061B high performance option and discipline some > really good XO. Certainly, the 10811 isn't the world's best > XO. You'll need to prevent your XO from getting bothered > by microphonics, stray magnetic fields, 2G turnover, temperature > fluctuations, and humidity if not hermetic , etc. The 5071A is > impervious to all that as it is. > > Is that what you had in mind? > > I remember before I worked for HP visiting JPL's Goldstone > tracking station. They had a 5061A that disciplined a > hydrogen maser for VLBI. They said a plain 5061A was useless for their > work. OTOH, a hydrogen maser without drift correction was > also useless for their work. They had a huge room with 100's > of racks of equipment, but the 5061A and H maser had their > own dedicated room. > > Rick Karlquist N6RK > _______________________________________________ > 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.