[time-nuts] The 10811 double oven mystery

[Bob kb8tq]

Hi

Running a hard disk at -40 C is pretty much a no-go sort of thing. Even finding CPU 
or FPGA chips rated for operation down there is difficult / expensive. DRAM chips with
the “right” timing … not so much.  Bottom line - the heater / HVAC costs *way* less than 
designing all that stuff to work over a wide temperature range. 

Bob

> On Apr 8, 2020, at 9:58 PM, Hal Murray <hmurray at megapathdsl.net> wrote:
> 
> 
> kb8tq at n1k.org said:
>> Well, based on conversations with the people who designed the part,  the
>> outer oven’s only function was to take care of a potential cold end  problem.
>> At the time, the telecom guys were thinking of putting GPSDO’s in systems
>> with no heating on the enclosures. That idea died when they ran into a
>> variety of issues with the digital side of things at cold temperatures. 
> 
> What's the problem with digital gear at cold temperatures?  The only one I can 
> think of is that electrolytic capacitors stop working when the electrolyte 
> freezes.
> 
> Do signal integrity problems appear when the rise time from CMOS drivers gets 
> faster?
> 
> What sort of warmth did the telecom guys decide they needed?  I live in 
> California, at sea level rather than up in the mountains.  We get occasional 
> freezing from radiation cooling on clear nights.  They wouldn't have to work 
> very hard to keep a box above freezing.  I'll have to look closer the next 
> time I see some cell phone antennas.
> 
> 
> -- 
> These are my opinions.  I hate spam.
> 
> 
> 
> 
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