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

[Matt Huszagh]

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