[time-nuts] TCXO improvement

[Bob kb8tq]

Hi

The “normal” approach is to stabilize the inner wall and cross section (= open tube) 
of the dewar. Often this is done with a metal “plug”. It may or may not extend to the 
bottom of the dewar. A lot depends on fiddly little details about how much heat
you are generating in the circuitry inside the “controlled area”.

Bob

> On Aug 2, 2019, at 10:51 AM, Dana Whitlow <k8yumdoober at gmail.com> wrote:
> 
> Question:
> 
> Do you stabilize the oscillator inside the dewar, or do you stabilize the
> temperature of
> the dewar's outside environment?
> 
> This may boil down to a slightly different expression:  Where do you *sense*
> the temperature for
> the stabilization loop?  On the crystal itself, or on the outside wall of
> the dewar?
> 
> Thanks,
> 
> Dana
> 
> 
> On Fri, Aug 2, 2019 at 4:00 AM Bill Slade <slade_bill at hotmail.com> wrote:
> 
>> Hello!
>> I have done this and can attest that it works well.  I did not use a TCXO,
>> though.  I used a 48 MHz, third-overtone AT-cut crystal in a Colpitts
>> oscillator configuration.  The vacuum flask was ovenized to maintain
>> temperature near the stationary point of the temp characteristic (near 50
>> deg C).   The oscillator could be phase locked to an external atomic
>> reference (in our case, a rubidium) or 10 MHz from a GPS receiver.
>> 
>> The inspiration was a couple of excellent NASA reports from some years
>> ago, which I have attached (as links because files are large) for
>> convenience.
>> Cheers,
>> Bill
>> Nasa Precision Quartz 1<
>> https://onedrive.live.com/embed?cid=3CBCA1CF8AB21FE1&resid=3CBCA1CF8AB21FE1%213504&authkey=AA4EqyT05-Iz2nU&em=2
>>> 
>> Nasa Precision Quartz 2<
>> https://onedrive.live.com/embed?cid=3CBCA1CF8AB21FE1&resid=3CBCA1CF8AB21FE1%213505&authkey=AEG_NqxtMFVIE_o&em=2
>>> 
>> 
>> On 02/08/19 01:35, Perry Sandeen via time-nuts wrote:
>> 
>> Yo Bubba Dudes!,
>> If one has the space, a simple cure might be to get one of the wide mouth
>> thermos containers that they sell in large variety stores such as Wal-Mart
>> for being able to eat something like stew or some semi-solid hot food out
>> of the container itself.
>> Regards,
>> Perrier
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