[time-nuts] Thunderbolt temperature measuring

WB6BNQ wb6bnq at cox.net
Sun Jul 26 21:06:23 UTC 2009


Mat,

I think the purpose of the DS1620 is to integrate the "ambient" temperature into
the equation used by the T-bolt.  I suspect that the ovenized internal oscillator
has its own temperature control.  That being the case, then it would be
counterproductive to couple the DS1620 to the oscillators container.

The sensitivity of the "ambient" sensor depends upon its significance in the
equation, whose composition is not really known.  However, it can be inferred by
observing the results of various testing.  The thread on this subject is the
results of a series of observations made over a fairly long time.

Mark Sims has been the point man with this problem and has been doing a lot of
investigation into this area and would be the one to correct the record.  The
above is my take on what I have read of his posts.

Bill....WB6BNQ

Mats Engstrom wrote:

> Hi,
>
> I've been lurking on this list for a long time but now it's time to unlurk.
>
> I don't remember if it's appropriate to introduce oneself on this
> list, but I'll do it anyways. :)
>
> I've been tinkering with electronics for some thirty odd years now -
> mostly just as a hobby but also occasionally semi-professionally.
> Most of my stuff is microcontroller based (AVR and/or PIC) - mostly in
> assembly,but C is also ok for some projects - higher level languages
> are for whimps :).  I'm Swedish by birth but living and working in
> Dubai in the IT/Finance industry since a couple of years.
>
> I just bought a Thunderbolt from flyingbest at Ebay to use as a nice
> timebase for my counters and signal gens.  I discovered that it had a
> bad DS1620 tempsensor that always reported -55 C so I replaced it with
> a thru-hole version that I happened to have some spares of. I then got
> a nice 24.xxxxx C temperature readout in Lady Heather. (When I tested
> the tbolt without the DS1620 it reported a temperature between -0.5 to
> -1.5 C)
>
> Now I'm finally coming to the question: Since I'm using a thru-hole
> version of the DS1620 and have to use cables between the chip and the
> circuit board I could possibly extend the cables a bit so I can glue
> (with a non termo-insulating glue) the chip onto the ocxo itself to
> have a tighter coupling between them.  Would that improve the
> stability or is it better to just measure the air temperature in the
> box?
>
> /mats
>
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