[time-nuts] Rubidium standard

[phil]

----- Original Message ----- 
From: "David Smith" <w6te at msn.com>
To: "Discussion of precise time and frequency measurement" 
<time-nuts at febo.com>
Sent: Thursday, November 12, 2009 2:31 AM
Subject: Re: [time-nuts] Rubidium standard


I'm new to the list. Having said that, I ran across a webpage from a chap in 
Australia or maybe it was New Zealand. In any event he claims that the Rb 
lamp can be brought back to life. He says that he has rejuvenated over 30 
units with bad lamps and they work great after his "process."

I will try and dig up the webpage if anyone is interested.

Dave / W6TE
  ----- Original Message ----- 
  From: Hal Murray<mailto:hmurray at megapathdsl.net>
  To: Discussion of precise time and frequency 
measurement<mailto:time-nuts at febo.com>
  Sent: Wednesday, November 11, 2009 11:15 PM
  Subject: Re: [time-nuts] Rubidium standard



  > I was told by a Technical Support Engineer from Symmetricom Global
  > Services that "The typical life span is ~10 years for these Rubidium
  > Time Bases".

  > This is in response to my request for information on a Ball/Efratom
  > PTB-100.

  > Is this a typical life span of a rubidium standard?

  It's lower than what I would expect.  The target market is the Telco and 
Cell
  Phone industry.  They expect (or at least used to) long lifetimes.

  Maybe "life span" means how long they run it, planning to replace it with
  newer gear long before it actually wears out.

  I would have expected more like 20 years of useful life.  That's running 
24x7
  in a reasonable environment.  That's also with hacker reliability, aka 
it's
  not a disaster if it dies.  So if you get one that was dumped by a Telco
  after 10 years, it's not crazy to run it 24x7 and expect many more years.
  (Just as long as you don't go crazy if it doesn't last that long.  I can 
buy
  a lot of surplus stuff for the price of new gear as long as I'm willing to
  tolerate the time gaps and effort of replacing it when it dies.)


  The LPRO-101 blurb says:
    Amb.Temp: 20 °C 25 °C 30 °C 40 °C 50 °C 60 °C
    MTBF (hrs) 381k 351k 320k 253k 189k 134k

  A year is 8760 hours (ignoring leap years).  Call that 10K.  So they 
expect
  25 years at 40C and 32 years at 30C.

  That's calculated MTBF.  YMMV.


  > Do some standards last longer than others?

  I'm sure some are better than others.  I don't have any data.


  > What are the symptoms of a failing rubidium bulb?

  Externally?  It stops working.  The error signal (maybe a LED too) will go
  on, or rather the locked signal (open collector?) will go off.

  The frequency stability will fall off a cliff.


"He says that he has rejuvenated over 30 units with bad lamps and they work 
great after his "process." "
Is this what you were referring to? Near the end he explains how to 
"rejuvenate" lamps.
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