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 <[email protected]> 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 > > [email protected] > 604 762 4099 > >> On Apr 8, 2020, at 7:09 PM, Bob kb8tq <[email protected]> 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 <[email protected]> wrote: >>> >>> >>> [email protected] 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. >>> >>> >>> >>> >>> _______________________________________________ >>> time-nuts mailing list -- [email protected] >>> To unsubscribe, go to >>> http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com >>> and follow the instructions there. >> >> >> _______________________________________________ >> time-nuts mailing list -- [email protected] >> To unsubscribe, go to >> http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com >> and follow the instructions there. > > _______________________________________________ > time-nuts mailing list -- [email protected] > To unsubscribe, go to > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > and follow the instructions there. _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
