[time-nuts] CBT designation and usage?

Tom Van Baak tvb at LeapSecond.com
Fri Sep 27 15:16:39 EDT 2013


Hi Mike,

Cs tubes with "S" are standard-performance; tubes with "H" are high-performance. You can get that from the tube label, or from the front panel S/N. Don't trust the black dot on the rear of the instrument: frames change, tubes change, Sharpies add dots, acetone removes them.

It depends on what you want the 5071A for. National labs keeping timescales prefer the H tubes since they are several times more stable than the S tubes. Casual labs prefer the S tube since they last much longer than H tubes. You have a standard tube. The good news is that it appears to work. Surplus, working, 5071A are not common.

Your frame and tube S/N are quite low, meaning old. But I don't know of a way to tell if the instrument has been used a little or a lot during the last 20 years. There's no "running hour" meter in the tube itself, the hardware, or the software so AFAIK there's no way to tell how used it is. But do read:
www.dtic.mil/cgi-bin/GetTRDoc?AD=ADA484993
www.dtic.mil/cgi-bin/GetTRDoc?AD=ADA508048
5071A_FAQs_Symm_Web.pdf
www.ke5fx.com/cs_life.pdf

Your syst:print? output looks ok to me. It would be interesting if you compared your 5071A 1PPS against a GPS timing receiver for a week or month. Then I could tell you better how well your 5071A is working.

/tvb



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