[time-nuts] Re: PRS10: What are good values for AD9 and DS?

[Krishna Makhija]

Hi Matt,

I have just recently bought two new PRS10s. I ran these commands for you on
them. Here is what I see:
FS!?
Result: 64,257,1347,1264 (unit1), 59,233,2569,2611 (unit2)
DS?
Result: 1070,1124 (unit1), 1053,983 (unit2)
AD9?
Result: 2.981 (unit1), 3.155 (unit2)

Not sure why the number of power cycles and running time is so high. I have
personally only power cycled them 5-6 times so far for testing and used
them for a total of 10-15 hours. Perhaps it was part of the factory
calibration/testing? I might have to look into this later. At any rate, I
am pretty sure they are working fairly close to factory spec.

Cheers,
Krishna

On Wed, Nov 16, 2022 at 12:54 AM Matt Huszagh via time-nuts <
time-nuts at lists.febo.com> wrote:

> Hi,
>
> I recently received a used PRS10. The unit appears to work fine, but may
> be a bit old. The serial number is 18508, which is lower than many of
> the others I've seen. Additionally, running FC!? reports
> "79,10910,1564,2194". First number is number of power cycles. The second
> number is the number of updates to the FC value. This value can be
> updated manually, or is updated each power cycle or 12 hours. If this
> wasn't updated manually many times, that suggests a very long operating
> life (about 15yrs).
>
> So, I wanted to get a sense of how healthy the unit is. The manual
> describes two commands that seem to give an indication of health: DS?
> and AD9?
>
> The second number from DS? is the mV RMS strength of the "synchronously
> detected signal at twice the modulation frequency." The manual also
> says: "The amplitude of this signal is proportional to the strength of
> the rubidium hyperfine transition signal." The manual states an example
> of a good value is 55,800. Mine reports the second number between 670
> and 680. The first number is low and oscillates around 0, as
> expected. What is a good range for this second number? Is 670
> reasonable?
>
> The other command is AD9?, which is the photocell's I/V converter
> voltage divided by 4. Mine shows 2.168. Any idea what's a healthy value
> for this? Any other commands to run/check? Based on the age of this unit
> (assuming the FC command is not misleading), should I only expect a few
> years out of this unit, or is it hard to tell?
>
> Thanks
> Matt
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