[time-nuts] Re: Frequency Standard - Where Can I Get One.

[Skip Withrow]

Hello Time-Nuts,

No offense Bob, but I would like to take issue with your statement 'Rb
standards have a finite life'.

There are time-nuts on this list of every skill and knowledge level
and I would like to keep the information as correct as possible.  My
feeling is this is not a true statement.

There is nothing inherent in the design of a rubidium frequency
standard that limits its life (unlike cesium).  However, there are
manufacturing choices that can possibly limit time before failure.

First example, of course, is the HP 5065.  There are many of us that
have units that have been running continuously for close to 50 years.
HP made choices in their bulb design that ensures that it runs for a
very long time.

An opposite example would be the Tracor rubidiums.  The lamps in these
units were either horribly underfilled, or the glass was very reactive
with Rb and almost all suffered from rather early lamp failures.

Then, there is the huge mass of telecom rubidiums.  As you stated,
keeping the base plate at a reasonable temperature goes a LONG way to
extended life.  Excessive temperature obviously leads to higher
component (and sometimes lamp) failure.

There are also units that just did not have enough design margin in
certain areas.  The SRS PRS-10 is one of these where I have seen
things go up in smoke in the lamp area.  BTW, the HP 5065 can have
some issues in this area as well.

I'm obviously a big fan of rubidium frequency standards.  My advice to
newer time-nuts is that you can't go wrong owning one (better long
term stability than OCXO, lots less cost and longer life than cesium).

I'll get off the soap box now.  Thanks for the bandwidth.

Skip Withrow