Hi Paul, About cesium clocks: hp 5060A and early versions of the hp 5061A needed to be able to keep *either* atomic time (true, accurate, stable, SI seconds) or astronomical time (inaccurate, unstable, slow, and gradually slowing, earth rotation time).
The larger C-field range allowed this user choice of time-scales. I have many examples of both clocks here. It appears most time & frequency labs converted to "atomic time" in the late 60's and 70's which is why all later 5061A, all 5061B, every 5071A, and all modern atomic/ion/optical clocks tick "atomic" seconds instead of the slightly larger and monthly / seasonally / climatically / geologically / gravitationally variable "earth" seconds. And why we have leap seconds. In the past 50 years even die-hard astronomers have thrown in the towel and conceded that atomic time is a more stable time reference than earth rotation rate. In order to point modern, super-accurate telescopes they use a high-precision (sub-millisecond!) "DUT1" correction to convert physics-stable atomic time into engineering-accurate astronomical time; "close enough for government pointing work" as they say. Now that we're well into the post-astronomical time age, the narrow C-field range is adequate. If you have a 5060 or older 5061 there is no harm in using resistors to restrict the C-field range. /tvb (i5s) > On Jan 3, 2014, at 7:51 AM, paul swed <[email protected]> wrote: > > Corby > Having a good time tinkering with the 5061. Did change the resistors for > the cfield regulator so that its much close to the schematic and am > experimenting with that. > The system does seems to be able to be tuned through a stable position that > reduces the drift to 2 min/10ns drift and the CS is slow compared to the > 5065 RB set to loran C when its on the air. > I do have a older synth div board. No thumbwheel switches. It appears to me > to be jumpered at 8634. I think that may be wrong. The book says 2095 for > atomic time. > Appreciate your thoughts. > Regards > Paul > > >> On Thu, Jan 2, 2014 at 4:52 PM, paul swed <[email protected]> wrote: >> >> Corby >> I pulled the a15 board and there are no resistors, just a short across >> what would have been r19 and 21. So I suspect that there is to much current >> actually. Further speculation is that when the pot is toward ground more >> current flows from what I see in the schematic. >> I may guess that more current equals lower frequency? >> Regards >> Paul. >> >> >>> On Thu, Jan 2, 2014 at 4:22 PM, <[email protected]> wrote: >>> >>> Paul the C-field current is the same for the 5061A and 5060A. >>> >>> The 5060A C-field pot has LOTS more range than the later 5061A where they >>> installed resistors on each side of the pot to reduce the range. >>> >>> Corby >>> >>> _______________________________________________ >>> time-nuts mailing list -- [email protected] >>> To unsubscribe, go to >>> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >>> and follow the instructions there. >>> >> >> > _______________________________________________ > time-nuts mailing list -- [email protected] > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
