[time-nuts] HP10544A Confusion

Bruce Griffiths bruce.griffiths at xtra.co.nz
Fri May 29 14:58:09 UTC 2009


Jim

Where did you get the idea that the 10544A uses an AT cut crystal?
At least some of them used a BT cut crystal.
There are 2 sets of specs for the 10544A.
The specs on the earlier data sheets are worse than the specs on the
later data sheets.

Bruce

Jim Flanagan wrote:
>
> Hi..
> I need help understanding a few things in regards to my 10544A
> oscillator.
>
> I was given an osc about 5 years ago that did not have the oven
> controller.  The
> owner at that time had built his own version which did not work well. 
> I completely
> removed everything he had done and duplicated the original oven using the
> osc schematics that are available.  At that point the osc went on the
> shelf until
> a couple of weeks ago.  I decided to go ahead and calibrate the oven
> temperature
> in order to select the correct resistor to set the temp at the turning
> point.
>
> Here is my confusion:
> I understand that the 10544 oscillators used AT cut crystals, which
> means that
> after warmup, I need to tweak the temp for a freq MIN.  Whereas, for
> an SC
> cut xtal osc we would be looking for a freq MAX.  For both xtal cuts
> the turning
> point is typically set for somewhere in the 75 - 85 C range.  I see
> where my
> 10544 osc is sitting about 1.5KHz LOW at room temp and then increases
> in freq at warmup (OVEN temp rising).  I thought that at room temp the
> freq (for AT osc) would be HIGH and decrease in freq as the oven warms.
> After a full warmup, I would then adjust the temp slowly, watching the
> freq for
> a min, at which time, as the oven is made hotter, the freq would then
> start in the
> opposite direction(positive).
>
> In my mind, my osc seems to act as though it is using an SC cut
> crystal...
> Is my thinking all wrong here?
>
> I've been studying he classic df/f vs Temp curves and my osc appears
> to be
> opposite of the curves, assuming my osc does use an AT xtal.
>
> I would appreciate someone setting me straight in regards to this..
> Thanks
> Jim
> jflan at tampabay.rr.com
>
>
>
>
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