[time-nuts] CBT designation and usage?

mc235960 mc235960 at gmail.com
Fri Sep 27 16:07:08 EDT 2013


Le 27 sept. 2013 à 21:16, Tom Van Baak a écrit :

> 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.

  I thought so, but the figures looked ok so I went for it anyway.

> 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.

  Shame, especially considering that it must have cost around 50k new. 

> 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

 Thanks for these links. 

> 
> 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.

  That looks like a good plan. I was going to just discipline the PPS against a timing receiver right off , but it would be interesting to see what its free running perf is like before I tweak that knob. 

> 
> /tvb
> 
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