Hi,

So, on that note. I am surprised that I have not seen popular telecom rubidiums being reverse-engineered. For instance, the LPRO-101 should have been reverse-engineered a long time. Some of the circuitry is known from patents, but those do not build up a complete schematic. I've considered to do the job, but apparently I have not been able to sit down and do that particular job either.

I think the LRPO-101 should not be too much of a challenge. Beyond the schematic some documentation of the other functions, hints and tips, etc. that is related should be written up so one approach something similar to a service manual.

With enough people contributing, I think it should not be too hard to collect things. We should be able to provide useful hints and tricks, such as suitable replacement components etc.

Cheers,
Magnus

Den 2021-11-21 kl. 19:45, skrev Bob kb8tq:
Hi

Well, if I could keep a 5065 running without repairs for more than a couple 
years
I might be more willing to agree with you. What makes the 5065 different is 
that you
have schematics and can do repairs. When the telecom gizmos die, there’s not 
much
to fall back on. They were designed to run a finite amount of time and then go 
to the
scrap heap.

Bob

On Nov 21, 2021, at 12:03 PM, Skip Withrow <[email protected]> wrote:

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
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