Re: [time-nuts] 5070B once more.... (actually 5370A fans)
Magnus wrote: Having 1-10 kW per rack is not uncommon these days, so forced convection needs to be done That and more. A fully loaded 42U rack of HP C-class blades runs 8 kW idle and peaks at 24 kW. This can be air cooled (easily) in a properly designed and commissioned run-of-the-mill raised floor data center. It is unfortunatly common to see racks where one box has an airflow left-to-right while ontop of it is one with right-to-left and the rack has very narrow space between the side of the boxes and the sides Hot aisle/cold aisle arrangement is current best practice. (Colleagues in my group at HP Labs were the first to do CFD analysis on data centers and established many of today's best practices.) The key is to avoid mixing of cold and hot air as that destroys exergy. IT equipment is mostly well-behaved as typically installed. There is a one notable exception -- rack switches are often mounted from the rear and blow hot air out the front into the cold aisle. (HP recently announced a switch where the flow can be reversed where need be.) The other problem, which you have alluded to, is gear intended for a telco environment. Unfortunately that includes most data center core switches. These, as you indicate, typically exhaust to the side. -ch ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] 5070B once more.... (actually 5370A fans)
In message , Mark Sims writes: > >Many failed electrolytic caps on PC motherboards and in PC power supplies >can be traced to a case of industrial espionage gone wrong. [...] While this tale is true, the fact is that even without incompetence, electrolytics suck. -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] 5070B once more.... (actually 5370A fans)
Poul-Henning Kamp wrote: > It is worth pointing out that a very large fraction of all electronics > failures are not semiconductors but electrolytic capacitors. > > People are often astonished when I tell them, that a "long life" > electrolytic capacitor is one which will last one year at its rated > temperature, whereas a standard consumer-grade will last only a > month. Len Cutler apparently knew that. On the 5071A project, we had long meetings about which capacitor to use in the power supply filter. Len wanted to use a mil spec tantalum for reliability, but the cost was astonomical for the large capacitance we needed. We talked him into using a really good aluminum one. Rick Karlquist ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] 5070B once more.... (actually 5370A fans)
Mark Sims skrev: The power dissipated in a modern CPU chip (watts per sq cm) far exceeds that of a cooking hotplate. There are some videos on YouTube showing CPU's literally exploding when they loose cooling for just a short time. ECL is a rather chilly iceberg in comparison... The Cray-1, where the core is ECL only, uses the board ground plane to connect out to the mountings which is infact cooling walls called cold bar. They had problems to manufacture those in aluminium to hold the circulating freon properly. The power was fed to the supplies under the seats in 12-phase 400 Hz AC (12 phases after transformer, 3 phases from power-converter) such that after rectifying only very little filtering is needed to kill the ripple. While the hungriest modules was consuming 65 W, density wise a modern CPU puts it to shame. The Cray-3 on the other hand... the modules was just bathing naked into cooling fluid. Cheers, Magnus ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] 5070B once more.... (actually 5370A fans)
Poul-Henning Kamp skrev: In message <4a170da2.3080...@rubidium.dyndns.org>, Magnus Danielson writes: Hal Murray skrev: There are being books written about this. One that I have found being a fairly short but useful one is the AT&T Reliability Manual. It is worth pointing out that a very large fraction of all electronics failures are not semiconductors but electrolytic capacitors. People are often astonished when I tell them, that a "long life" electrolytic capacitor is one which will last one year at its rated temperature, whereas a standard consumer-grade will last only a month. To add insult to injury, many of them have rated temperatures of only 85°C and much of the discount electrocrap uses 55°C grade. For modern consumer crap, yes... for traditional pro-gear caps may eventually need replacement, but if you look at them as standard 1 km replacement parts it becomes less of an issue and just a matter of remember to do it. My experience from well-designed pro-gear is that caps could very well survive but a silicon device might eventually fail. Vibration or mechanical movement wear is another issue for long-term reliability issue, where components detach from solder and move in tunnels of solder at the end, connecting part of the time and only fractional at some time. Modern electrolytics is a different story altogher from traditional electrolytics. My stationary computer failed in the PSU. Sure enougth it was caps. But looking carefully at the errupted caps you could also see that even through there is a fan there, the air flows over the top and often the caps sits next to the switch transistors and their heat sink. What else to expect? The same electronics but spread over twice the volume and with the electronics sitting more in a "wind-tunnel" than forming a side of it would have made it last longer. The compactness of todays electronics often come at the price of reliability. The caps is smaller in physical size for the same reason, and guess what suffer. The electrolytics becomes more critical, and hence the issue of stealing the formula, where as the traditional electrolytics was a different story... Cheers, Magnus ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] 5070B once more.... (actually 5370A fans)
In message <971f24636bd13158d9fe412ec6c9c885.squir...@webmail.sonic.net>, "Rick Karlquist" writes: >The old photos of Len Cutler watching the airline porters carrying >the clock up the stairs to the plane give the impression that >the airline was honored to be asked to participate. According to a SAS employee who was involved, HP paid for tourist class tickets for the personel, but was given the entire front 1st class row & VIP treatment, including access to 110VAC power. Poul-Henning -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] 5070B once more.... (actually 5370A fans)
In message <4a170da2.3080...@rubidium.dyndns.org>, Magnus Danielson writes: >Hal Murray skrev: >There are being books written about this. One that I have found being a >fairly short but useful one is the AT&T Reliability Manual. It is worth pointing out that a very large fraction of all electronics failures are not semiconductors but electrolytic capacitors. People are often astonished when I tell them, that a "long life" electrolytic capacitor is one which will last one year at its rated temperature, whereas a standard consumer-grade will last only a month. To add insult to injury, many of them have rated temperatures of only 85°C and much of the discount electrocrap uses 55°C grade. Poul-Henning -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] 5070B once more.... (actually 5370A fans)
M. Warner Losh wrote: > In message: <20090522185851.4137db...@ip-64-139-1-69.sjc.megapath.net> > Hal Murray writes: > : > : rich...@karlquist.com said: >> : Did you have any trouble convincing the airlines and/or FAA that it was > safe > : to take an atomic clock on a plane? I never heard about any issues of hand carried atomic clocks. The old photos of Len Cutler watching the airline porters carrying the clock up the stairs to the plane give the impression that the airline was honored to be asked to participate. There is a very long story about this that boiled to the the idea that the cesium beam tube itself has been approved as a shipping container for the cesium. If you have ever picked up a cesium beam tube, you will appreciate that it is built like a battleship. Thus it requires no special shipping container for either a replacement tube or an instrument. The tube says "cesium device; nonradioactive". Rick Karlquist N6RK ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] 5070B once more.... (actually 5370A fans)
Hal Murray wrote: The reason for the fans is to prevent premature failures of the silicon devices due to thermal degradation. The life of a silicon chip is halved for every 10C temperature increase, more or less. I was going to make a similar comment, but got sidetracked poking around google. I didn't find a good/clean article. Does anybody have a good URL? Doubling every 10C is the normal recipe for chemical reactions. I think that translated to IC failure rate back in the old days. Is that still correct? Has modern quality control tracked down and eliminated most of the temperature dependent failure mechanisms? Hal, The old standby is MIL-HDBK-217F: http://assist.daps.dla.mil/quicksearch/basic_profile.cfm?ident_number=53939 It is quaint, but they based it on years of experience. They did a lot of testing of the chips and created mathematical models that worked as well as any model can, given the clumpiness of failures. P.5-13 gives the temperature failure rate multiplier for ECL chips: 25C 0.10 45C 0.27 55C 0.42 65C 0.63 75C 0.94 85C 1.4 95C 1.9 So my off-the-cuff guess of failures doubling for every 10C rise is not too wrong. --David Forbes, Tucson ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] 5070B once more.... (actually 5370A fans)
Hal Murray skrev: The reason for the fans is to prevent premature failures of the silicon devices due to thermal degradation. The life of a silicon chip is halved for every 10C temperature increase, more or less. I was going to make a similar comment, but got sidetracked poking around google. I didn't find a good/clean article. Does anybody have a good URL? Doubling every 10C is the normal recipe for chemical reactions. I think that translated to IC failure rate back in the old days. Is that still correct? Has modern quality control tracked down and eliminated most of the temperature dependent failure mechanisms? I remember reading a paper 5 or 10 years ago. The context was disks. I think the main failure was electronics rather than mechanical. It really really really helped to keep them cool. There are being books written about this. One that I have found being a fairly short but useful one is the AT&T Reliability Manual. A criticism on reliability calculations (say from Bob Pease) is that if you remove protection circuits from the design, the MTBF calculations says the design improves (as there are fewer devices contributing their FITS) while the actual design is less reliable as protection would have avoided premature failure. This criticism is valid only if blindfolded beleif in MTBF is allowed to rule the judgement of reliability, since the methodology assumes otherwise sound engineering practices to avoid over-voltage, over-current, over-heating and other forms of excess stress that is within the limits for which the design is intended to operate and be stored in. Anyway, there have been much research into the reliability of electrical devices and in general, keeping a sufficiently low temperature is among the things which improves reliability. For silicon the junction temperature limit needs to be ensured by having the component ambient temperature limited (usually to 70 degrees as measured inbetween two DIP-packages for intance), which has yeat another temperature drop into the (self) convected air and the ambient temperature of an rack of electronic (as measured 1 meter from the floor, 3 dm from the rack) to a maximum of 45 degrees. The 19" rack standard was originally designed for a total of 300 W per rack, so self convection up through the installed boxes would work. Having 1-10 kW per rack is not uncommon these days, so forced convection needs to be done, which puts requirement on different manufactures to have a common air-flow dicipline, which also needs to consider that no heat may be put out on the front for safety reasons (you shall never hesetate to hit the on/off switch). It is unfortunatly common to see racks where one box has an airflow left-to-right while ontop of it is one with right-to-left and the rack has very narrow space between the side of the boxes and the sides, so effectively the boxes feeds each other with pre-heated air until one of them dies. Another example where a particular switch which had a left-to-right airflow, which was sitting at the top of a line of computing rack for a parallel computing setup. They where feeding a step wise increasing temperature air flow going through all the racks. The last switched died prematurely. In parallel computing heat management and power management can be a much more troublesome issue than load balancing between the CPUs, which is the kind of luxury problem you can deal with at a later stage. Cray was a refrigeration company, which also delivered alot of CPU cycles along the way. Cheers, Magnus ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] 5070B once more.... (actually 5370A fans)
In message: <20090522185851.4137db...@ip-64-139-1-69.sjc.megapath.net> Hal Murray writes: : : rich...@karlquist.com said: : > First of all, the 5071A has to be able to run on a battery, so you can : > do the flying clock experiment. : : Did you have any trouble convincing the airlines and/or FAA that it was safe : to take an atomic clock on a plane? : : I'd be more worried about the big batteries than the cesium. Most clock flying experiments are done on military aircraft Warner ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] 5070B once more.... (actually 5370A fans)
> The reason for the fans is to prevent premature failures of the > silicon devices due to thermal degradation. The life of a silicon > chip is halved for every 10C temperature increase, more or less. I was going to make a similar comment, but got sidetracked poking around google. I didn't find a good/clean article. Does anybody have a good URL? Doubling every 10C is the normal recipe for chemical reactions. I think that translated to IC failure rate back in the old days. Is that still correct? Has modern quality control tracked down and eliminated most of the temperature dependent failure mechanisms? I remember reading a paper 5 or 10 years ago. The context was disks. I think the main failure was electronics rather than mechanical. It really really really helped to keep them cool. -- These are my opinions, not necessarily my employer's. I hate spam. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] 5070B once more.... (actually 5370A fans)
Hi! Regarding the comments below on the 5370: there are always two questions with temperature: meeting spec and reliability. Instruments vary as to which is a bigger issue. Some have temperature proof measurement techniques that will work virtually until something burns up, so you can get lulled into a false sense of security just because the instrument meets spec. I think most people would agree that reliability comes in the first room, specs in the second. It is fairly meaningless to have super-spec when you know that your box is approaching dysfunctional at a high speed, and you don't know when what effect will kick in to fiddle with your performance before it says "poof" on you. Infact, cooling (for reliability) and performance to some degree can become troublesome, as the noise of the airflow and vortexes can affect performance and forced air onto ovens will make very efficient connection between ambient temperature and oven shield, so any shift there will quickly and effectively cool or heat the oven. Self convected boxes has longer time constants than forced air boxes. Many times when I "investigate" the design of boxes I react on their inability to design for reliability. I react on very basic design errors such as mechanical mounting of heavy components (solder is not long term stable fixing when heat and vibration comes into play) and heat (when the heat sink forms a heat-pocket into which all heat gathers and stays rather than distribute the heat sources so dissapation through self convection becomes easy is just another example). Repairing failed gear can be rewarding in terms of understanding failure modes. Becoming experienced in various forms of failures is as important as understanding how to perform the task of the project. Cheers, Magnus ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] 5070B once more.... (actually 5370A fans)
rich...@karlquist.com said: > First of all, the 5071A has to be able to run on a battery, so you can > do the flying clock experiment. Did you have any trouble convincing the airlines and/or FAA that it was safe to take an atomic clock on a plane? I'd be more worried about the big batteries than the cesium. -- These are my opinions, not necessarily my employer's. I hate spam. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] 5070B once more.... (actually 5370A fans)
In message , Mark Sims writes: >I was rather surprised to see that, if anything, the internal jitter went > down a couple of picoseconds That could easily be reduced microphonics in the OCXO because the new fan does not rattle around as much. -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] 5070B once more.... (actually 5370A fans)
In message <4267588cdd7544d48a9a119584228...@pc52>, "Tom Van Baak" writes: >I'm sure this requires no small effort in thermal engineering on >their part. The major part of this effort was to reduce the power usage to maximize battery lifetime. >The plot you get is then simply accuracy (or jitter or drift) versus >air flow. This plot, more than one or more raw temperature probe >measurements or IR pictures, will tell you what the ideal range of >air flow is. I have no idea what you'd find. But it would settle the >question about fan replacement for the 5370. Its a good idea, but it does not resolve the reliability issue. -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] 5070B once more.... (actually 5370A fans)
At 10:13 AM -0700 5/22/09, Tom Van Baak wrote: One comment, and one idea on airflow... I'm sure we could discuss for some time what airflow is too much or too little or where to place the thermal probes or how to take IR scans or how then interpret them. But it seems to me the bottom line is not what the temp is inside, but how the unit performs; how stable the time interval counter is. voltco; tempco; airco? /tvb Tom, The fans in a 5370B have nothing to do with stability; if anything, they make it worse. The reason for the fans is to prevent premature failures of the silicon devices due to thermal degradation. The life of a silicon chip is halved for every 10C temperature increase, more or less. In a world of perfect thermal engineering, the chips would be attached to a metal plate that is kept at a constant temperature. But that's impractical for cost, weight and maintenance reasons. Given that many of these ECL chips are no longer made, keeping them cool for long life is of utmost importance. -- --David Forbes, Tucson, AZ http://www.cathodecorner.com/ ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] 5070B once more.... (actually 5370A fans)
Tom Van Baak wrote: > One comment, and one idea on airflow... > > I've noticed that none of my high-end frequency standards use > fans at all. That includes every Rb, Cs, and H-maser. This does > not mean they are all cool to the touch, but my guess is it's better > to allow temperature gradients to exist than use fans in an attempt > to even then out. > > I'm sure this requires no small effort in thermal engineering on > their part. But it also has the side effect of 100% quiet instruments > and no mechanical wear-out mechanism. Of course, you don't > want to exceed a high temp limit on any one component, but the > point is passive heat transfer with metal seems to be the better > choice than active transfer with air and fans. Maybe I can put this into perspective with my experience on the 5071A team. First of all, the 5071A has to be able to run on a battery, so you can do the flying clock experiment. This limits the power consumption to a few dozen watts. Considering the size of the 5071A, that little amount of power consumption has plenty of heat sinking and doesn't need a fan. The power supply uses highly efficient Vicor modules. The one thing that is probably not so well designed is the AC power transformer. However, it gets a pass, because it doesn't affect power consumption when on battery, and it is perfectly OK for the transformer to cook itself as long as the insulation is rated for the temperature rise. Other than that, there is really no way a transformer can fail. Another thing is that if any fan were used, it would raise the issue of microphonics in the 10811 oscillator, which is a serious issue in the 8662A signal generator. Len Cutler would have insisted on a microphonic witch hunt if we had used a fan, so we were all glad we didn't have to go through that. The RF circuits were in machined boxes that conducted away heat pretty well. They had a modest internal temperature rise. Regarding the comments below on the 5370: there are always two questions with temperature: meeting spec and reliability. Instruments vary as to which is a bigger issue. Some have temperature proof measurement techniques that will work virtually until something burns up, so you can get lulled into a false sense of security just because the instrument meets spec. Rick Karlquist N6RK Member of 5071A design team, circa 1992. > > Now, a suggestion for the 5370 question. > > I'm sure we could discuss for some time what airflow is too much > or too little or where to place the thermal probes or how to take IR > scans or how then interpret them. But it seems to me the bottom > line is not what the temp is inside, but how the unit performs; how > stable the time interval counter is. voltco; tempco; airco? > > It doesn't matter if you measure a +10C change inside but it has > little effect on the jitter or accuracy of the counter. Similarly, if a > tiny +1 C change at some special point causes many picoseconds > of drift then that's something more to worry about. > > So my suggestion is for someone to take a 5370 and set it up to > take continuous phase measurements between two stable inputs > (or delay generator, or a tee from a common reference) and then, > vary the airflow from way too low to way too fast. You could do > this in steps every 10 minutes, or linearly over hours, etc. > > The plot you get is then simply accuracy (or jitter or drift) versus > air flow. This plot, more than one or more raw temperature probe > measurements or IR pictures, will tell you what the ideal range of > air flow is. I have no idea what you'd find. But it would settle the > question about fan replacement for the 5370. > > /tvb > > > ___ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. > > ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] 5070B once more.... (actually 5370A fans)
One comment, and one idea on airflow... I've noticed that none of my high-end frequency standards use fans at all. That includes every Rb, Cs, and H-maser. This does not mean they are all cool to the touch, but my guess is it's better to allow temperature gradients to exist than use fans in an attempt to even then out. I'm sure this requires no small effort in thermal engineering on their part. But it also has the side effect of 100% quiet instruments and no mechanical wear-out mechanism. Of course, you don't want to exceed a high temp limit on any one component, but the point is passive heat transfer with metal seems to be the better choice than active transfer with air and fans. Now, a suggestion for the 5370 question. I'm sure we could discuss for some time what airflow is too much or too little or where to place the thermal probes or how to take IR scans or how then interpret them. But it seems to me the bottom line is not what the temp is inside, but how the unit performs; how stable the time interval counter is. voltco; tempco; airco? It doesn't matter if you measure a +10C change inside but it has little effect on the jitter or accuracy of the counter. Similarly, if a tiny +1 C change at some special point causes many picoseconds of drift then that's something more to worry about. So my suggestion is for someone to take a 5370 and set it up to take continuous phase measurements between two stable inputs (or delay generator, or a tee from a common reference) and then, vary the airflow from way too low to way too fast. You could do this in steps every 10 minutes, or linearly over hours, etc. The plot you get is then simply accuracy (or jitter or drift) versus air flow. This plot, more than one or more raw temperature probe measurements or IR pictures, will tell you what the ideal range of air flow is. I have no idea what you'd find. But it would settle the question about fan replacement for the 5370. /tvb ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] 5070B once more.... (actually 5370A fans)
I came home one day to find *that* smell in my workshop. It turned out to be my HP 3325B. It had been on for ages and it had also been a warm day. I looked at the back and found the intake completely blocked up with dust. It seems to still work, but I need to open it right up and check it out properly. So, yes, in conclusion air flow is important! Jim 2009/5/22 Mark Sims > > A8? Reference buffer? Gee, I thought was the electrostatic dust magnet ;-) > That puppy can grow more fuzz than a sheepdog. In all the machines I > have worked on, it was utterly disgusting. > > BTW, the best way to locate where to drill the access hole for the > oscillator tuning pot is to look on the underside of the top cover. The > oscillator compartment will be outlined in dust. Measure the tuning screw > location from the sides of the oscillator compartment with calipers and > transfer the measurements to the dust outline... it's more accurate than > measuring from the edges of the box. > > > > > _ > Hotmail® has ever-growing storage! Don’t worry about storage limits. > > http://windowslive.com/Tutorial/Hotmail/Storage?ocid=TXT_TAGLM_WL_HM_Tutorial_Storage1_052009 > ___ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. > ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] 5070B once more.... (actually 5370A fans)
The ECL and EECL chips are located on A22 (arming board), A19 + A20 (interpolator boards), A18, A17 (count chain assembly) A8 (reference buffer), A21 (multiplier assembly). The interpolator boards are more or less directly in line with the ducted airflow from the fan as are the reference buffer and frequency multiplier boards. A22 which has most of the ECL and EECL logic is mounted at right angles to the initial ducted fan airflow which impinges on its rear surface. >From this point some air flows through the gap between A22 and the side panel and flows across the font of A22, the input amplifier and schmitt trigger boards and the front panel board. The rear of A22 also deflects airflow back through thecard cage and the other boards. The crystal oscillator is screened from direct airflow by a sheet aluminium shield. Thus the airflow is quite complex and one would need to monitor the temperatures of a large number of chips and other components to ensure the cooling is appropriate. Since the top and bottom covers also affect the airflow it would be difficult to use a thermal camera to meaningfully monitor chip temperatures. Even if the top and bottom covers were replaced with infrared transparent materials, a thermal vision camera won't have a clear view of all the EECL and ECL chips. Bruce Rick Karlquist wrote: > Hal Murray wrote: > >> How much ECL is used in a 5070? >> > > A bunch > > How tightly are they packed? > > You need a high cooling velocity even if just one chip. > > >> How much of >> the heat goes directly from the chip to the air rather than from chip to >> board to air? >> > > A substantial amount of cooling is from DIP to air, unlike tiny > SMT packages used now. > > >> How much room is there above the chips? Many years ago I saw some neat >> > > Probably not much extra room. > > Rick Karlquist N6RK > > > ___ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. > > ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] 5070B once more.... (actually 5370A fans)
When I worked in R&D at HP's Microwave Division (1972 ~ 1976) and HP LaserJet Division (1976 ~ 2000) we designed all our products to meet specifications across a temperature range of -20 to +55 degrees Centigrade. I would assume this was a standard requirement across most if not all HP products although I can't be sure. Therefore if you are operating your HP equipment in an office environment you can probably reduce air flow some without a significant degradation in performance. On the other hand, as has been reiterated here many times, cooler is always better from a reliability standpoint. Therefore I would personally hesitate to reduce the air flow in any of my HP gear. Jim Hall W4TVI ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] 5070B once more.... (actually 5370A fans)
Hal Murray wrote: > How much ECL is used in a 5070? A bunch How tightly are they packed? You need a high cooling velocity even if just one chip. > How much of > the heat goes directly from the chip to the air rather than from chip to > board to air? A substantial amount of cooling is from DIP to air, unlike tiny SMT packages used now. > How much room is there above the chips? Many years ago I saw some neat Probably not much extra room. Rick Karlquist N6RK ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] 5070B once more.... (actually 5370A fans)
> This is incorrect. ECL components require a minimum airflow velocity > that is rather high. The purpose of the large fan is to maintain this > velocity. If a smaller fan is used, the ECL components will get > hotter, even though the air flowing past them is not much hotter. > When you say the fan didn't make any real difference in cooling inside > the unit, did you measure the temperature of the ECL DIP's? How much ECL is used in a 5070? How tightly are they packed? How much of the heat goes directly from the chip to the air rather than from chip to board to air? How much room is there above the chips? Many years ago I saw some neat add-on heat sinks. They were heavy copper foil with double sided sticky tape. They had a couple of fins sticking up into the air flow. They weren't serious heat sinks, but good enough to help if all you needed was a little. -- These are my opinions, not necessarily my employer's. I hate spam. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] 5070B once more.... (actually 5370A fans)
Part of the problem is that in some equipment (not all, but based on my experience, most), the noise comes from not from the fan itself, but from poor air routing inside the equipment itself. The air moving around encumbered passage makes noise. As someone pointed out earlier, take the fan out of the equipment for a few seconds, in most cases the noise will be much less. So if the noise is a function of the air flowing over components, the fan type makes no difference, the same air flow will produce the same noise. In some cases, the fan itself may be the primary cause of the noise, and when that happens, the fan is usually deffective (worn bearings, or damaged/dirty blades.) In that case, replacing the fan with the same model but new will fix the problem. I recently replaced the fan on an HP power supply. With the fan out of the enclosure, you could clearly tell the fan was bad, and the new one (same model) was almost quiet. Once in the chassis, it did not make that much of a difference. There was less whine from the fan itself, but the noise from the air flow over the heat sinks and the grill was dominating the noise from the fan. Part of a good design is to design the cooling for the expected environment. Therefore, a well designed piece of equipment will have adequate cooling, but not more than is needed to meet the requirements, otherwise it will be wasted money. And while much equipment is designed to operate at up to 50 degree C ambient, many only do so at degraded performance. Nominal performance on most precision instruments is only achieved within a typically narrow range around 25 degree C or thereabout, which is where the equipment is calibrated. So, think twice before reducing the air flow, regardless of other considerations (reliability) justly pointed out by others. Didier -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Poul-Henning Kamp Sent: Thursday, May 21, 2009 12:12 PM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] 5070B once more (actually 5370A fans) In message <4a15808f.4090...@karlquist.com>, "Richard (Rick) Karlquist" writes: >"Modern" fans obey the same laws of physics as the original equipment. >They don't magically produce more airflow for less noise. Agreed: there is no magic to it. But a lot has happened in aerodynamics since Hermann Papst invented the external rotor motor and had to add fans to keep it cold. In recent years noise from air transport have become a competition parameter, and these days you can buy standard fans that move twice as much air at the same dB level, as you would have found five years ago. As for reducing air-flow in old kit: I wouldn't do that without a careful session with a thermovision camera. Poul-Henning -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] 5070B once more.... (actually 5370A fans)
> -Original Message- > From: time-nuts-boun...@febo.com > [mailto:time-nuts-boun...@febo.com] On Behalf Of Richard > (Rick) Karlquist > Sent: Thursday, May 21, 2009 9:26 AM > To: Discussion of precise time and frequency measurement > Subject: Re: [time-nuts] 5070B once more (actually 5370A fans) > get a bit cooler and some a bit warmer. > > This is incorrect. ECL components require a minimum airflow > velocity that is rather high. The purpose of the large fan > is to maintain this velocity. If a smaller fan is used, the > ECL components will get hotter, even though the air flowing > past them is not much hotter. When you say the fan didn't > make any real difference in cooling inside the unit, did you > measure the temperature of the ECL DIP's? "Modern" fans obey > the same laws of physics as the original equipment. They > don't magically produce more airflow for less noise. It's not necessarily magic. It's things like better blade design that gets you same air performance with less noise. I used to work for a company which made fans for use in the theatrical/entertainment market (so quiet is important). We went through dozens and dozens of different blade/housing configurations to find ones that were both quiet and performed well. Unfortunately, it's a task that is not made simpler by CFD modeling.. The relationship between flow and sound production is so complex that empiricism (i.e. trying lots of ideas) is cheaper (unless you're designing propellors for nuclear submarines). And, once you have a design that works, you have to be careful about patent infringement. Each "muffin fan" vendor has patents on their particular blade design. It > would also be a mistake to assume automatically that all HP > equipment is overdesigned. I remember one logic analyzer was > referred to internally as the "logic furnace", which had a > high failure rate. And there's the 8663A signal generator as well. > > Rick Karlquist N6RK > > ___ > time-nuts mailing list -- time-nuts@febo.com To unsubscribe, > go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. > ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] 5070B once more.... (actually 5370A fans)
In message <4a15808f.4090...@karlquist.com>, "Richard (Rick) Karlquist" writes: >"Modern" fans obey the same laws of physics as the original equipment. >They don't magically produce more airflow for less noise. Agreed: there is no magic to it. But a lot has happened in aerodynamics since Hermann Papst invented the external rotor motor and had to add fans to keep it cold. In recent years noise from air transport have become a competition parameter, and these days you can buy standard fans that move twice as much air at the same dB level, as you would have found five years ago. As for reducing air-flow in old kit: I wouldn't do that without a careful session with a thermovision camera. Poul-Henning -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] 5070B once more.... (actually 5370A fans)
Mark Sims wrote: I have done quite a bit of work replacing fans in old equipment with modern fans. I have never seen a case where replacing a hurricane level fan with a whisper quiet fan made any real difference in the cooling inside the unit... typically one sees less than +/- 5C difference anywhere inside the box. Some places get a bit cooler and some a bit warmer. This is incorrect. ECL components require a minimum airflow velocity that is rather high. The purpose of the large fan is to maintain this velocity. If a smaller fan is used, the ECL components will get hotter, even though the air flowing past them is not much hotter. When you say the fan didn't make any real difference in cooling inside the unit, did you measure the temperature of the ECL DIP's? "Modern" fans obey the same laws of physics as the original equipment. They don't magically produce more airflow for less noise. It would also be a mistake to assume automatically that all HP equipment is overdesigned. I remember one logic analyzer was referred to internally as the "logic furnace", which had a high failure rate. Rick Karlquist N6RK ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] 5070B once more.... (actually 5370A fans)
When I have been concerned with 'stealing' power, I have used a switching power supply wall wart. Small and are usually quite efficient. One model a Sony (branded), the chip inside even had a opto isolated control pin so it could be turned on/off via logic. -pete > > > Yes, I have replaced the fans in four 5370A and 5370B counters with > modern 12V brushless DC motor units connected to the 10V supply. VERY > nice and quiet. I did before and after thermocouple tests in the chassis. > The temperatures were basically unchanged (+/- 3C). Variances could > easily have been due to the probes shifting. > > I have also done several dozen HP16500 logic analyzers and Tektronix > TM5003 and TM5006 mainfarmes. On the TM5003 and TM5006, I run the fan on > 8V. They are almost dead silent. > > > Use the lowest current fan that you can find... they tend to be the > quietest. > _ > Hotmail® has ever-growing storage! Dont worry about storage limits. > http://windowslive.com/Tutorial/Hotmail/Storage?ocid=TXT_TAGLM_WL_HM_Tutorial_Storage1_052009 > ___ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. > ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] 5070B once more.... (actually 5370A fans)
On 5/20/09 9:18 AM, "Roy Phillips" wrote: > Mark > Thanks for your comments. I suspect that there was a period when the "Papst" > fan was the de facto standard in many equipments, it has considerable depth > and obviously moves a lot of air. There is no real correlation between noise level and airflow or efficiency. (a very tiny part of the energy goes into making noise). A 20-30 dB difference in SPL isn't unusual, for identical airflow. You might check into other brands/models that have the same flow at the same static pressure. Another big noise source is turbulence from components around the fan (e.g. A strut that intercepts a shed vortex from each blade can make a lot of noise. If Nstruts = Nblades you're in bad shape. I can certainly see the need in the case > of Power Supplies, I have an HP6632A which can provide 100 watts of power. > But a good example of overkill was the HP 3456A Digital Voltmeter, the > earlier models were fitted with a fan, which was subsequently removed in > later issues. I have an older model and I have disconnected the fan (it was > a small type), it was obviously not needed. > I have an HP 5334A, and a HP5335A, the latter being more obtrusive. Perhaps > the design considerations were based on the US, with its higher summer > temperatures,not such a problem for us Europeans. > Roy > > > > - Original Message - > From: "Mark Sims" > To: > Sent: Wednesday, May 20, 2009 4:53 PM > Subject: [time-nuts] 5070B once more (actually 5370A fans) > > > > > Yes, I have replaced the fans in four 5370A and 5370B counters with modern > 12V brushless DC motor units connected to the 10V supply. VERY nice and > quiet. I did before and after thermocouple tests in the chassis. The > temperatures were basically unchanged (+/- 3C). Variances could easily have > been due to the probes shifting. > > I have also done several dozen HP16500 logic analyzers and Tektronix TM5003 > and TM5006 mainfarmes. On the TM5003 and TM5006, I run the fan on 8V. They > are almost dead silent. > > > Use the lowest current fan that you can find... they tend to be the > quietest. > _ > Hotmail® has ever-growing storage! Don¹t worry about storage limits. > http://windowslive.com/Tutorial/Hotmail/Storage?ocid=TXT_TAGLM_WL_HM_Tutorial_ > Storage1_052009 > ___ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. > > > > ___ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. > ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] 5070B once more.... (actually 5370A fans)
Mark Thanks for your comments. I suspect that there was a period when the "Papst" fan was the de facto standard in many equipments, it has considerable depth and obviously moves a lot of air. I can certainly see the need in the case of Power Supplies, I have an HP6632A which can provide 100 watts of power. But a good example of overkill was the HP 3456A Digital Voltmeter, the earlier models were fitted with a fan, which was subsequently removed in later issues. I have an older model and I have disconnected the fan (it was a small type), it was obviously not needed. I have an HP 5334A, and a HP5335A, the latter being more obtrusive. Perhaps the design considerations were based on the US, with its higher summer temperatures,not such a problem for us Europeans. Roy - Original Message - From: "Mark Sims" To: Sent: Wednesday, May 20, 2009 4:53 PM Subject: [time-nuts] 5070B once more (actually 5370A fans) Yes, I have replaced the fans in four 5370A and 5370B counters with modern 12V brushless DC motor units connected to the 10V supply. VERY nice and quiet. I did before and after thermocouple tests in the chassis. The temperatures were basically unchanged (+/- 3C). Variances could easily have been due to the probes shifting. I have also done several dozen HP16500 logic analyzers and Tektronix TM5003 and TM5006 mainfarmes. On the TM5003 and TM5006, I run the fan on 8V. They are almost dead silent. Use the lowest current fan that you can find... they tend to be the quietest. _ Hotmail® has ever-growing storage! Don’t worry about storage limits. http://windowslive.com/Tutorial/Hotmail/Storage?ocid=TXT_TAGLM_WL_HM_Tutorial_Storage1_052009 ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
