[time-nuts] Hp 5060A C-field

[paul swed]

OK seems no matter what I do compared to the Tbolt and Z3801the 5061/5060
still drifts right on the scope. Granted a big shift in the cfield seems to
get the unit to advance, but then after some hours it returns back to the
same slow rate. But I did learn about the magical A1 synthesizer and built
an excel calculator to see what the jumper settings do. If anyone wants it
I will forward it.
Putting the A! synth on the bench and feeding a 5 Mhz source in I could see
how it behaved. It tends to run a little high in frequency. I mean
fractions of a hertz.
As far as the jumpers go one change really does move the synth quite a ways
from the atomic frequency. So what I learned is that changing the jumpers
really would make a heck of a jump either fast or slow, not some fine grain
shift.
Regards
Paul
WB8TSL


On Fri, Jan 3, 2014 at 9:04 PM, paul swed <paulswedb at gmail.com> wrote:

> 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) <tvb at leapsecond.com>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 <paulswedb at gmail.com> 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 <paulswedb at gmail.com> 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, <cdelect at juno.com> 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
>> >>>
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