Tom and Corby Thanks for the help. I suspect that the 5060/5061 is perhaps as good as it can get. My other references such as the 3801 and Tbolt have it down now in the 1X10-11 region. Close to 1 but goes above and below. I did find the magical cfield R to be 70 ohms and will have to calculate the current. When I do measurements for 10 ns displacement it takes some 13-18 minutes. I also use a 5370b counter much easier to measure the ns drift than the scope. Regards Paul WB8TSL
On Fri, Jan 3, 2014 at 1:13 PM, Tom Van Baak (lab) <[email protected]>wrote: > 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. > _______________________________________________ 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.
