[time-nuts] Bad batch of HP10811's

[Dr Bruce Griffiths]

Jeroen Bastemeijer wrote:
> Dear Time-nuts,
>
> New info on an old subject:
>
> I opened the counter (5345A) to check what kind of oscillator was 
> inside. It was a 10544A instead of a 10811A!!!
>
> I checked for a datasheet of the 10544 but I couldn't find it. Luckily I 
> ran across an article in HP Journal. See the quote below:
>
> Warmup. The 10811A/B Oscillator cuts the 10544/B/C
> warmup time specification in half: 10 minutes for the
> 10811A/B compared to 20 minutes for the 10544A/B/C Oscillator.
> Warmup time is defined as the time between oscillator
> oven turn-on and the time when the output frequency
> is within 0.05 Hz of the operating frequency, In portable
> instruments, where battery weight must be minimized, low
> power and quick warmup are crucial. Since the instrument
> warmup time is likely to be much shorter than the oscillator
> warmup time, the latter usually dominates. A side benefit of
> the 10811A/B is that its frequency just after oven turn-on is
> only 100 Hz low compared to 1 kHz low for the 1054aA/B/C.
> This allows faster lock-in for instruments using phaselocked
> loops.
>
> Bottom line: The 10544 gives a higher offset at switch-on compared to 
> the 10811.
>
> Only thing to do now is find a datasheet to verify it with real numbers, 
> as my oscillator was 1700 Hz off (compared to 1 kHz in the article) and 
> Didiers' oscillator was 200Hz off (compared to 100 Hz in the article).  
> Is there a link to the 10544 datasheet somewhere out there???
>
> Have a nice weekend, Jeroen
>
>   
Jeroen

There are at least 2 versions of the 10544A. After the initial 
production models modifications were made to improve the phase noise specs.
The oscillator, oven controller and oven supply volatage specifications 
also changed after this modification.
I have a set of datasheets  dated:  1 October 1972, July 75, July 1976.
There is no specification on the datasheet for the frequency offset at 
startup with a cold oven.
Any idea when your oscillator was manufactured?

Bruce