Re: [time-nuts] The 10811 double oven mystery
On Donnerstag, 9. April 2020 03:58:11 CEST Hal Murray wrote: > 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. The two most common problems are that gates switch too fast so timing margin disappears and leakage gets too low so that the biasing of semi-floating nodes (in dynamic circuits, say) can't be maintained. If the part isn't qualified for low temperatures to start with you can also have with breakdown and latch- up problems. Some degradation mechanisms are also accelerated at cold temperature, so lifetime goes down. The fun thing is that none of the functional problems might happen when the temperature goes down gradually while the part is continually operating (due to self-heating) but you might not be able to power up gear that has been sitting in the cold overnight. Testing at cold is already spectacularly difficult because every little remnant of moisture wants to freeze on the stuff you're trying to test, but when you need to also test for cold soaking then you really wish that this wasn't part of the specification. Plus you not only need to qualify all the parts, but after that the components and the whole system as well. If you have the power available, just specifying a more comfortable ambient temperature inside the cabinet is going to massively reduce the effort on that front (that's still tricky because you'll want non- condensing conditions at all time and maybe a few other things). > Do signal integrity problems appear when the rise time from CMOS drivers > gets faster? That can happen too. > 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. Last time I've peeked into one it simply had a small shrouded fan heater in there. It's easy enough to figure out what amount of power is sufficient to achieve whatever delta-T at minimum ambient you're targeting and if that still fits your power budget you're done. Regards, Achim. -- +<[Q+ Matrix-12 WAVE#46+305 Neuron microQkb Andromeda XTk Blofeld]>+ Waldorf MIDI Implementation & additional documentation: http://Synth.Stromeko.net/Downloads.html#WaldorfDocs ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
Re: [time-nuts] The 10811 double oven mystery
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 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 > > m...@alignedsolutions.com > 604 762 4099 > >> On Apr 8, 2020, at 7:09 PM, Bob kb8tq 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 wrote: >>> >>> >>> kb...@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. >>> >>> >>> >>> >>> ___ >>> time-nuts mailing list -- time-nuts@lists.febo.com >>> To unsubscribe, go to >>> http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com >>> and follow the instructions there. >> >> >> ___ >> time-nuts mailing list -- time-nuts@lists.febo.com >> To unsubscribe, go to >> http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com >> and follow the instructions there. > > ___ > time-nuts mailing list -- time-nuts@lists.febo.com > To unsubscribe, go to > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > and follow the instructions there. ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
Re: [time-nuts] The 10811 double oven mystery
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 m...@alignedsolutions.com 604 762 4099 > On Apr 8, 2020, at 7:09 PM, Bob kb8tq 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 wrote: >> >> >> kb...@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. >> >> >> >> >> ___ >> time-nuts mailing list -- time-nuts@lists.febo.com >> To unsubscribe, go to >> http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com >> and follow the instructions there. > > > ___ > time-nuts mailing list -- time-nuts@lists.febo.com > To unsubscribe, go to > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > and follow the instructions there. ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
Re: [time-nuts] The 10811 double oven mystery
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 wrote: > > > kb...@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. > > > > > ___ > time-nuts mailing list -- time-nuts@lists.febo.com > To unsubscribe, go to > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > and follow the instructions there. ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
Re: [time-nuts] The 10811 double oven mystery
kb...@n1k.org said: > Well, based on conversations with the people who designed the part, the > outer ovenâs only function was to take care of a potential cold end > problem. > At the time, the telecom guys were thinking of putting GPSDOâs 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 -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
Re: [time-nuts] The 10811 double oven mystery
On 4/8/2020 2:02 PM, Tom Holmes wrote: Then what was the purpose of the inner oven? Tom Holmes, N8ZM -Original Message- The inner oven has a thermal gain around 1,000. When my colleagues at HP proposed to wrap a 2nd oven around it, I predicted that the additional thermal gain due to this oven would not be much, and they proved me right by building it. and measuring it. It's raison d'etre is dealing with low ambient temperatures. Any thermal gain improvement is just a bonus. The designers downplayed this bonus since it wasn't anything to brag about. Rick N6RK ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
Re: [time-nuts] The 10811 double oven mystery
On 4/8/2020 12:53 PM, Jarl Risum wrote: I have been puzzled by a mistake which has been published recently on this list and elsewhere as well. It concerns the operation of the HP 10811 double oven TCXO used in the HP Z3801 GPSDO. It is claimed that the outer oven is only in use during start up or during extremely low ambient temperatures and is not operating during normal conditions. This is not correct. Jarl ___ How did you determine that the statement is not correct? There will be some ambient temperature at which the outer oven heater power reaches zero and therefore it becomes inactive above that. All you are arguing about is whether the shutdown temperature is correctly described in terms of "extremely low" and "normal", whatever those adjectives mean. Rick ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
Re: [time-nuts] The 10811 double oven mystery
Then what was the purpose of the inner oven? Tom Holmes, N8ZM -Original Message- From: time-nuts On Behalf Of Jarl Risum Sent: Wednesday, April 08, 2020 3:53 PM To: time-nuts@lists.febo.com Subject: [time-nuts] The 10811 double oven mystery I have been puzzled by a mistake which has been published recently on this list and elsewhere as well. It concerns the operation of the HP 10811 double oven TCXO used in the HP Z3801 GPSDO. It is claimed that the outer oven is only in use during start up or during extremely low ambient temperatures and is not operating during normal conditions. This is not correct. The 10811 outer oven circuit in the HP Z3801 is designed to maintainin a stable temperature around the 10811-60158 OCXO somewhere in the interval between 60 and 65 deg. C in order to reduce the 10811-60158 OCXO's sensitivity to temperature changes which – without the outer oven - is specified as 4,5 x 10 e-9 from 0 to 71 deg. C. The HP Z3801 was made as a GPS disciplined timebase for synchronization of CDMA Cellular Wireless Land Network base stations and was required to maintain system syncronization for up to 24 hours in situations with failure of GPS reception. In order to satisfy this requirement, the HP Z3801's internal processor keep track of the gradual ageing of the 10811 during normal GPS-disciplined operation and applies a calculated, predicted correction voltage to keep the OCXO on frequency during periods with no GPS signal (HP's Smart Clock technology). A diagram and detailed description of the 10811 outer oven circuit can be found at KO4BB's manual collection under http://www.ko4bb.com/getsimple/index.php?id=manuals&dir=02_GPS_Timing/Z3801. Pictures of the outer oven can be found at www.realhamradio.com/GPS_Frequency_Standard.htm. In 2013 Warren Sarkison published an improved 10811 Outer Oven Controller with improved temperature regulation. Description and numerous references to his design can be found by Googling ”Warren S. Design 10811 Outer Oven Controller”. This circuit - or something similar - is much to be recommended if optimum operation of the dual oven 10811 outside of the HP Z3801 is considered. Jarl ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there. ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
Re: [time-nuts] The 10811 double oven mystery
Hi 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. The issue isn’t the *sensitivity* as much as the simple fact that the 10811 will not warm up at all from a really cold temperature. There just isn’t enough heater power. If you want to dig into just why a “jacket” like this is not going to give you super oven performance, the various papers Rick published on his single oven are a good start. Bob > On Apr 8, 2020, at 3:53 PM, Jarl Risum wrote: > > I have been puzzled by a mistake which has been published recently on this > list and elsewhere as well. It concerns the operation of the HP 10811 > double oven TCXO used in the HP Z3801 GPSDO. > > It is claimed that the outer oven is only in use during start up or during > extremely low ambient temperatures and is not operating during normal > conditions. This is not correct. > > The 10811 outer oven circuit in the HP Z3801 is designed to maintainin a > stable temperature around the 10811-60158 OCXO somewhere in the interval > between 60 and 65 deg. C in order to reduce the 10811-60158 OCXO's > sensitivity to temperature changes which – without the outer oven - is > specified as 4,5 x 10 e-9 from 0 to 71 deg. C. > > The HP Z3801 was made as a GPS disciplined timebase for synchronization of > CDMA Cellular Wireless Land Network base stations and was required to > maintain system syncronization for up to 24 hours in situations with > failure of GPS reception. In order to satisfy this requirement, the HP > Z3801's internal processor keep track of the gradual ageing of the 10811 > during normal GPS-disciplined operation and applies a calculated, predicted > correction voltage to keep the OCXO on frequency during periods with no GPS > signal (HP's Smart Clock technology). > > A diagram and detailed description of the 10811 outer oven circuit can be > found at KO4BB's manual collection under > http://www.ko4bb.com/getsimple/index.php?id=manuals&dir=02_GPS_Timing/Z3801. > Pictures of the outer oven can be found at > www.realhamradio.com/GPS_Frequency_Standard.htm. > > In 2013 Warren Sarkison published an improved 10811 Outer Oven Controller > with improved temperature regulation. Description and numerous references > to his design can be found by Googling ”Warren S. Design 10811 Outer Oven > Controller”. This circuit - or something similar - is much to be > recommended if optimum operation of the dual oven 10811 outside of the HP > Z3801 is considered. > > Jarl > ___ > time-nuts mailing list -- time-nuts@lists.febo.com > To unsubscribe, go to > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > and follow the instructions there. ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
