[time-nuts] 5071A Cs Oven

paul swed paulswedb at gmail.com
Thu Oct 4 19:41:51 UTC 2012


Rick
Well I have the old 5060 and 61 tubes and indeed they run out O gas.
I am using a 5060 tube in a 5061 and the Frankenstein works though it has
only a few Cs. But heck it all locks after 48 hours.
So someone said with humor lets buy some 5071 tubes for a couple hundred
each.
Guess I could have some fun getting that into the 5061. Suspect that would
be the bride of Frankenstein then.
Thanks for sharing the insights and experience.
Paul
WB8TSL

On Thu, Oct 4, 2012 at 3:21 PM, Richard (Rick) Karlquist <
richard at karlquist.com> wrote:

> These ideas are "interesting".  AFAIK, there is very little
> chance of running out of Cs in many years, long past the
> time when something else in the tube will have reached its
> end of life.  Where did this idea come from?  Certainly, not
> anyone working at HP, Agilent or Symmetricom.  A LONG time
> ago, if you bought a high performance 5061, the increased
> Cs beam flow might have been an issue, but the amount of Cs
> shipped with the tube was increased before the 5071A
> such that running out of Cs is no longer an issue.
>
> If you turn off the Cs, you simply have a 10811 to connect
> to your GPS.  Except this 10811 has 10X the EFC range vs
> a stock 10811.  Again, this doesn't make a whole lot of sense,
> IMHO.
>
> BTW, another "interesting" idea is degaussing the CBT.  According
> to Len Cutler, this is completely unnecessary in the 5071A.  As
> anyone who knew Len can attest, if he thought something was
> good enough and didn't need to be improved, you could be
> sure about that.  For example, Len wanted us to use tantalum
> filter capacitors for energy storage in the power supply.
> Fortunately, we talked him out of that (actually the $100+
> cost helped to convince him).
>
> Due to customer demand (the customer is always right :-) the Santa
> Clara Division eventually released a degausser.  One of the reasons why
> this is not necessary in the 5071A is the Zeeman line measurement
> of the magnetic C field.  The 5061 was open loop.  So again there
> may have been a grain of truth behind the folklore.
>
> Rick Karlquist N6RK
> Member of the 5071A design team
>
>
> On 10/4/2012 9:45 AM, Tom Van Baak wrote:
>
>> Bob,
>>
>> Right, not good. There should be a fault message associated with it.
>> Check the internal log.
>>
>> OTOH, to conserve cesium, I've heard that some people run 5071A in
>> standby mode most of the time and only turn on the cesium for a fraction of
>> an hour a day or a week (to recal the quartz). Running in this standby mode
>> is also advisable if one wants the best short-term performance out of a
>> 5071A, without the loop noise. In this respect it's just like a GPSDO - you
>> get the best short-term performance if you turn off disciplining.
>>
>> /tvb
>>
>>  Hi
>>>
>>> Is "Cs oven: 0.0V" a good thing on a 5071A?
>>>
>>> I suspect not, since either it or GPS is off frequency.
>>>
>>> Bob
>>>
>>
>>
>>
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