[time-nuts] The 10811 double oven mystery

[Bob kb8tq]

Hi

It was one of those things that sounded like a great idea when they first sketched
it up. Once they dug into the grubby details, it didn’t make as much sense. This was
back in the early 90’s. The guts of a cell tower were quite a stretch to come up with
back then, even at normal temperatures. 

Bob

> On Apr 8, 2020, at 10:52 PM, Mark Spencer <mark at alignedsolutions.com> wrote:
> 
> But cooling / heating systems designed to work over a Wide temperature range (ie. Parts of Northern Canada where outside temperatures of  perhaps -40C in the winter and +35C in the summer are within the relm of possibility) can be somewhat more expensive / complicated than systems designed for mild climates.
> 
> I can sort of see why someone might want electronic equipment that could work at -40C especially if the equipment was going to reside in an unattended shelter that was hard to get to.  I realize that in practice this is likely to be difficult (:
> 
> Mark Spencer
> 
> mark at alignedsolutions.com
> 604 762 4099
> 
>> On Apr 8, 2020, at 7:09 PM, Bob kb8tq <kb8tq at n1k.org> wrote:
>> 
>> 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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>> 
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