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

EWKehren at aol.com EWKehren at aol.com
Tue Aug 28 10:51:09 UTC 2012

If 5 V will not do it use a OPA 227 with a gain of 2. That is what I use as 
 my test rig.
Bert Kehren
In a message dated 8/27/2012 10:54:02 P.M. Eastern Daylight Time,  
mspencer12345 at yahoo.ca writes:

Thanks..  That seems like a good next step.

(Just to  add to this, all three of the units have functional trim pots and 
two of three  units will easily adjust to the correct frequency.)
> Message:  7
> Date: Mon, 27 Aug 2012 22:24:06 -0400 (EDT)
> From:  EWKehren at aol.com
> To: time-nuts at febo.com
> Subject: Re:  [time-nuts] Datum 1000B's any hints ?
> Message-ID:  <1003d9.2a828d17.3d6d85c5 at aol.com>
> Content-Type: text/plain;  charset="US-ASCII"
> without any EFC I would expect it to be 1  Hz low. If less
> than 5 Volt  will 
> get it on frequency I  would use a 78L12 from your main
> supply followed by a 
>   TI REF02. Worked for me.
> Bert Kehren
> In a message dated 8/27/2012 10:13:35 P.M. Eastern Daylight
>  Time,  
> mspencer12345 at yahoo.ca
> writes:
>  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.
>  Sent from my  iPad
>  _______________________________________________

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