[time-nuts] Efratom M100 Found on Ramco auction site.

[Bob kb8tq]

Hi

Even back in the era that the M100 was a brand new on the market sort of device, 
if you talked to the Efratom repair guys, they rarely saw lamp issues. This *was* 
back when things got repaired. Their guess was that only 1 in 10 returned units
had an issue with the optical chain. 

Heatsinking (or lack there of) *is* a good way to kill off an Rb early. Again, it’s not
the physics package that goes. It’s some fiddly little part on one of the support boards.
Raise the temp enough and you nuke the MTBF.

Indeed there are exceptions. I have a pile of parts (bought cheap) that all left the
factory with 80 (yes 80) C 1,000 hour caps in it. Where in the world you even get
those is unclear to me. Needless to say, replace those caps and most of the Rb’s 
come back to life.

Bob

> On Nov 2, 2020, at 9:14 PM, The Fiber Guru <fiber.guru at fiber.guru> wrote:
> 
> Ha, yes I am sure this group squeezes every ounce from the gear on hand!  I should have qualified my comments from the perspective that the Rb’s we use are in BITS clock in telephone offices and disciplined by 1 PPS from a GPS receiver.  When these systems chug along for a decade or more it is not unusual to see the Rb modules fail, but sometimes it is improper heat dissipation or lamps that go bad.  At any rate, Rb’s are rarely resurrected back to life here in USA, but are replaced.  Some of that is a matter of policy by the carrier proper....
> 
> We did at one time consider a side business repairing Rb modules, but in the end the carriers just wanted to know they had a new module, not a repaired module.
> 
> No basements here in Texas, so am jealous of the concept!
> 
> The Fiber Guru
> www.fiber.guru
> 
> 
>> On Nov 2, 2020, at 6:16 PM, Bob kb8tq <kb8tq at n1k.org> wrote:
>> 
>> Hi
>> 
>> One of the nice things about the broad reach of this list is that a pretty good
>> “database” of device performance can be compiled. In addition there *is* the
>> fact that even Rb’s can be repaired. The “toss it when it breaks” approach is
>> not a favorite with most list members. 
>> 
>> I have seen no reason to believe that powering an Rb down and running it for
>> < 5% duty cycle in any way is a bad thing. I have rebuilt a few dozen Rb’s 
>> and they seem to work pretty well in a “mostly off” usage pattern. 
>> 
>> Indeed I have never run into a Rb supplier that suggests constant on. That 
>> includes back when I worked for EG&G. It also includes re-selling several 
>> different Rb’s over the years. 
>> 
>> Sitting in the basement there are three Rb’s from the 1970’s and 80’s still
>> chugging along fine. They have been repaired a few times, but they still 
>> are performing much better than their original specifications ….
>> 
>> Bob
>> 
>>> On Nov 2, 2020, at 4:58 PM, The Fiber Guru via time-nuts <time-nuts at lists.febo.com> wrote:
>>> 
>>> I have noticed a number of Rb oscillators for sale on eBay over the years, but be aware of the limited lifetime of the oscillator.  In our experience, the life is the same whether constantly in use or just sitting on a shelf.  That said, life cycles vary greatly....
>>> 
>>> My advice to uses who have had a clock powered for years and want to move it.....do NOT power it down, use portable power (batteries) to keep it powered during the move (which takes great care).  Many old (8-12 years) Rb oscillators that have been powered will just not survive power down, getting cold then power back up.  It can happen, but we sell a lot of replacement Rb oscillators to replace those ranging from 8-15 years.  However, a good ocxo will last magnitudes longer than Rb.
>>> 
>>> We have not noticed a significant difference in lifetime among the Rb manufacturers.  Sometimes they are equally bad!
>>> 
>>> :)
>>> 
>>> The Fiber Guru
>>> www.fiber.guru
>>> 
>>> 
>>>>> On Nov 2, 2020, at 3:50 PM, Dave B via time-nuts <time-nuts at lists.febo.com> wrote:
>>>> 
>>>> https://www.bidspotter.co.uk/en-gb/auction-catalogues/ramco/catalogue-id-ramco-10255/lot-e55bd54e-6a87-44c7-8286-ac610134f040
>>>> 
>>>> Listed as a Crystal oscillator, but has a telltale mention of "Rb lamp
>>>> voltage signal" !
>>>> 
>>>> It's an Efratom Model M100  Listed for £5.00 UKP !  (Located in the UK.)
>>>> 
>>>> (There are also some MI/IFR 2025 signal generators listed, and other RF
>>>> stuff.)
>>>> 
>>>> No affiliation.
>>>> 
>>>> Dave G8KBV.
>>>> 
>>>> 
>>>> 
>>>> -- 
>>>> Created on and sent from a Unix like PC running and using free and open source software:
>>>> 
>>>> 
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>>> 
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>