Some manufacturers enclose the crystal or oscillator in styrofoam to maintain temperature stability and to prevent drafts.
Rick
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--- In TekScopes@..., "Dennis Tillman" <dennis@...> wrote:
Specifically, if you have a Temperature Controlled Crystal Oscillator (TCXO)
like you find in a few Tek TM5000 instruments with the high stability time
base option:
. Is it better to enclose the plugin with a solid aluminum top
extrusion, bottom extrusion, and side covers?
OR
. Is it better to allow it to breathe with a vented top, bottom and
side panels (the ones with all the holes)?
By BETTER mean which choice will result in a more stable TCXO frequency
output?
And by STABLE I mean the least drift over time,
And by TIME I mean anything from a day to a week.
ASSUMPTIONS:
Assume for arguments sake we are talking about a temperature controlled
environment like a home or office where the room temperature doesn't vary by
more than 10 deg F.
Assume there are no power line fluctuations.
Assume the local temperature rise due to the oven is not great enough to be
detrimental to the lifetime of the rest of the components around it.
Ignore crystal aging which is another matter.
It seems to me, if you enclose the plugin that the TCXO resides in, the
temperature will reach a stable equilibrium and fluctuate less than if you
ventilate the plug-in. But I think there are also good reasons to keep
things cool with a fan blowing heat away.
Is there a definitive answer or does it depend on something I might have
missed?
Dennis
