[time-nuts] Just any counter external reference and discipline mode.

[David G. McGaw]

I have an 8640B in the lab.   Bizarre instrument.

David

On 7/13/20 2:57 PM, Richard (Rick) Karlquist wrote:
>
>
> On 7/13/2020 11:34 AM, jimlux wrote:
>
>> There are also "frequency locked" devices that are not "phase locked" 
>> - they essentially discipline an internal oscillator by adjusting its 
>> frequency, but not with any sort of phase locked loop.
>>
>
> The 8640 famously worked (sort of) this way.  The cavity
> had an extremely limited electronic tuning range, and would
> only stay in lock for a few minutes before drifting off.
> It would do this even if you left it on 24/7.
> The display would then flash, and you had to release the
> lock button, retune the frequency using the mechanical
> cavity know, and then push the lock button back in.  Are
> you kidding me?
>
> Definitely in the "gee whiz", "because we can", or "too clever
> by half" category.  At least they didn't have the chutzpah to
> charge $ for this as an optional "feature".  The Navy, recognizing 
> that this was not sailor proof, had the feature/bug omitted from the 
> military
> version.  Good for them.
>
> Rick
>
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