[time-nuts] [hp_agilent_equipment] Re: Upgrade an HP 5342A microwave frequency counter to have an oven oscillator.

Scott McGrath scmcgrath at gmail.com
Tue Dec 2 09:04:12 EST 2014

The 5342A counter and the 5345A counters both predate the 10811A and were originally fitted with 10544A oscillators for the option 1 high stability timebase 

Once the 10811A was released the instruments were fitted with the 10811A as a production change going forward and service replacements were done using 10811A's

So in this case there is no need to overthink the oscillator choice for upgrading a 5342A counter.   

 If the 10811A is an edge connector version it will fit and provide better performance than standard TCXO

Content by Scott
Typos by Siri

> On Dec 2, 2014, at 4:53 AM, "Dr. David Kirkby (Kirkby Microwave Ltd)" <drkirkby at kirkbymicrowave.co.uk> wrote:
> On 2 Dec 2014 03:10, "wb6dgn_tom at att.net[hp_agilent_equipment]" <
> hp_agilent_equipment at yahoogroups.com> wrote:
>> Isn't the 10811 a "double oven" oscillator (an oven within an oven)?  I
> also believe it has anticipator circuitry to predict changes based on
> environmental parameters.  Or...am I confusing this with another oscillator?
> http://www.leapsecond.com/museum/10811a/10811a.pdf
> Has a data sheet.  I believe that there are variants of the 10811A that are
> double oven, but not all are.
> The fan is not blowing directly onto the oscillator,  as they are on
> opposite sides of the case. But they are both at the rear and given the
> instrument is only half the width of a 19" rack, maybe it is too close.
> I have not checked this myself,  but someone said that the 5342A pre-dates
> the 10811A, so if purchased a 5342A new with the high stability
> oscillator,  one would get another oscillator with a poorer specification.
> The  5342A/10811A combination is one of those things one would have to
> test, rather than guess. It would need some careful thought about how to do
> a worthwhile experiment.
> Anyway, as far as I am concerned,  it is certainly worth while fitting the
> 10811A, as even without any equipment other than my eyes, I can see the
> last few digits are not constantly changing every second or so.  There's a
> dramatic improvement in short term stability.  I would guess it has  2-3
> orders of magnitude better short term stability, based just at looking at
> the display.  Actual measurements would quantify the improvement.
> If I can get 100-1000x better performance,  for an upgrade that costs less
> than 25% of the instrument, that is worthwhile to me. Waiting 6 or so
> minutes to get a dramatic improvement in performance is not a big deal.
> Keeping it plugged in 24/7, for a bit more performance, is not worthwhile
> to me, but others may feel otherwise.
> Dave.
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