[time-nuts] HP5334B with 10544 OCXO

[Rick Karlquist]

Roy Phillips wrote:
> Mark
> By chance I have just today installed a recently acquired 10554 OCXO into
> my
> HP 5334B Counter.  Its has been running for 5 hours and is yet to
> stabilize - my Manual suggest that 24 hours is the required time. Despite
> reading the manual, I cannot see any reference to the change over from the
> "low grade" inbuilt oscillator - is this automatic or does it require a
> jumper alteration.  I seem to recall that Rick Karlquist  referred to a
> voltage "droop" in the PSU occurring, due to the additional load of the
> oven
> as a consequence of fitting the OCXO to the 5334B.  I assume that this is
> when the oven is taking maximum current - perhaps he will offer some help
> (again) as I cannot find his earlier comments ?  I note that the rear
> "simple" oscillators trimmer is still operative - should this be so ?, or
> is
> it indicative to a need to disconnect it ?
> Again, any comments would be appreciated.
> Regards
> Roy

I inherited the built in oscillator from the 5334A; it is a poor
design based on a 10116 ECL line receiver (HP part no 1820-0810,
near the rear panel switch that selects the external reference).
I believe that spare gates in the package are used to select the
10811 vs built in vs external ref.  I don't remember, but I suspect
plugging in the 10811 is detected somehow by the 10116.  I wouldn't
normally allow a design where it wasn't automatic.

When you say the rear panel trimmer is still operative, do you mean
it affects the frequency?  Is so, you are not running on the 10544.
The design should be obvious from the schematic, however I don't
have one and can't remember every detail from 25 years ago.

Rick