[time-nuts] Trimble Thunderbolt temperature judgment call

[Tom Van Baak]

I think "isolation" may work better than "insulation". The latter
attenuates external temperature variations from getting in but
at the same time also necessarily restricts heat flow going out.
The result is gradual overheating.

You might first want to determine just how temperature sensitive
your TBolt is or isn't. Also see if the response is quite different
between rapid and slow temperature changes.

It's possible that just putting it inside a air sealed metal box would
do the trick. And the thicker the metal the better (thermal mass).

Note that unlike a standalone OCXO, most GPSDO are less
sensitive to temperature changes. This is because they are a
closed system -- drift due to gradual changes in temperature are
simply swept away by the OCXO-GPS servo loop. It's the short
mechanical shock or temperature spikes that cause trouble, not
any slow smooth gradual environmental change.

Take all this with a grain of salt because I've not done tempco
work on the TBolt yet. If anyone else has data, now would be
a good time to give a report.

Thanks,
/tvb

----- Original Message ----- 
From: "Mike Naruta AA8K" <aa8k at comcast.net>
To: <time-nuts at febo.com>
Sent: Wednesday, November 19, 2008 10:34 AM
Subject: [time-nuts] Trimble Thunderbolt temperature judgment call


> 
> 
> I love my new Trimble Thunderbolt.
> Thank you TAPR and Time-Nuts!
> 
> 
> I was thinking of putting insulation
> all around the Thunderbolt to thermally
> stabilize it.  It's in my basement and
> the temperature there rarely gets above
> 18 C.
> 
> That would also help with my dedicated
> power supply, as the 12 volt sags when
> the Thunderbolt is started.  The power
> supply is beautiful one from a 1985 HP
> fiber optic mux.
> 
> 
> The manual says that operating temperature
> is up to 60 C.  If extra-insulated, is the
> oven plus other power going to raise the
> whole unit temperature too high?
> 
> Would insulating the Thunderbolt and
> raising its temperature lead to a shorter
> MTBF?
> 
> Should I tuck some foam around the oven
> instead?
> 
> Should I just run it ambient and let the
> oven do all the work?
> 
> 
> Mike - AA8K