[time-nuts] Thermal insulation choice?

Mark Spencer mspencer12345 at yahoo.ca
Sat Jan 7 00:01:19 UTC 2012


As an additional data point..

When experimenting with various forms of insulation for a thunderbolt board I found that a corrugated carboard box provided a noticeable decrease in temperature fluctuations while limiting the overall temperature rise.   Even small ammounts of additional insulation (ie. a few layers of thin flexible foam sheets maybe 2 mm thick used for wraping items for shipment) caused the temperature as reported by the thunderbolt to increase signficantly.  (Maybe 15 Deg C IIRC ?)




--- On Fri, 1/6/12, Magnus Danielson <magnus at rubidium.dyndns.org> wrote:

> From: Magnus Danielson <magnus at rubidium.dyndns.org>
> Subject: Re: [time-nuts] Thermal insulation choice?
> To: time-nuts at febo.com
> Received: Friday, January 6, 2012, 6:10 PM
> Rick,
> 
> On 01/06/2012 10:14 PM, Rick Karlquist wrote:
> > John Ackermann N8UR wrote:
> >> I am looking for a readily available (from Home
> Depot or other local
> >> source) insulating material to use in a chassis
> that's housing a
> >> sensitive OCXO.  My goal is just to slow down
> any external thermal
> >> transients so the oven loop has time to react
> gracefully.
> > 
> > Before making this into a science project, consider
> this data
> > point:  We converted the oscillator in a 10811 to
> run in mode
> > B at 10.95 MHz.  The tempco in mode B is about 30
> ppm per degree
> > C.  Needless to say, the converted 10811 was
> extremely sensitive
> > to crystal temperature.  I could wave my hands
> around it and notice
> > the temperature change from the air currents. 
> However, simply
> > putting the 10811 into a small empty cardboard box
> completely
> > solved this problem.  No rocket science
> necessary.  So in the
> > short term, this simple box was like a double
> oven.  Of course,
> > in the long run, the 10811 thermal gain is only 1000
> or so and
> > you can see the effect of the HVAC shutting down at
> 7PM, etc.
> 
> This is essentially what I've found quite useful at many
> times, quick air fluctuations affects crystals pretty good
> but just blocking the air helps to slow down things.
> Long-term creeps through but is not on the same scale.
> 
> A large enough cardboard box will leak over-temperature
> such that the oven keeps working.
> 
> Cheers,
> Magnus
> 
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