[time-nuts] Datum 1000B's any hints ?

[Mark Spencer]

Wondering if anyone has any practical suggestions as to the operation of stand alone Datum 1000B's.    Over the last 6 months or so I've acquired 3 of them and I haven't been that impressed with their performance.   I've got a nicely running FTS 1050 and an 8600 series bva along with time lab and some HP5370's so I'm reasonably confident in my references and test setup.   

I've been powering them from stand alone linear power supplies with separate supply and return leads for the oven and electronics and have left them alone for several weeks at a time.   I haven't touched the efc input yet and am wondering if leaving that floating could be causing issues.   I also tried running one of them from my stand alone 24 volt battery system which didn't seem to help.

They all seem to be gradually getting better over time but I'm thinking either I have three duds or there is something basic I'm missing (ie. perhaps I need to connect the efc input ?).  I'm also wondering what if anything to connect the case ground to.

The most promising of the bunch from an adev perspective is also off frequency by approx a hz or so but seems to be slowly drifting towards the correct value.

Any comments would be appreciated.

Regards Mark Spencer.

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