Re: [time-nuts] FE-5680A heat sink
I'm puzzled. I admit that I don't have a lot of experience with Rb standards, but I do have a bit of experience with the HP-5065A Rb standard. In the 5065A, the entire physics package is enclosed in an oven. Assuming that your Rb is the same, and I believe it is, your plan to force the physics package to run at room temperature is just going to make the oven work harder in its never ending quest to maintain stable temperature. If you monitor the current draw of the 5680A, you will probably see that it goes up when you put a fan on it. Sometimes, you just have to let electronics run hot. What did the manufacturer suggest? -Chuck Harris Leigh L. Klotz, Jr WA5ZNU wrote: I've attached an SMA connector to my FE-5680A and built an external linear power supply with a TO-3 7815. I ran the device today for about half an hour, and used an infrared sensing thermometer to measure the external case temperature. It got up to 48 C externally in the physics package area. I put a muffin fan on top and it brought it down to 38C but I don't think this is a good plan because I worry about the effects of the fan's magnetic field on the Rubidium system. I found in my junk box a finned Aluminum heat sink that's exactly the same size as the FE-5680A and plan to tap it around the edges for 4-40 hardware to attach to the many screw holes. Even so, this heat sink will be on the bottom, so the FE-5680A will have to be operated upside down for this to help. Has anybody got good thermal management solution for this device? This is the one currently selling on eBay in the 25x88x125mm chassis. Thanks, Leigh. ___ 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] FE-5680A heat sink
In message 4a2cfce2.5020...@erols.com, Chuck Harris writes: I ran the device today for about half an hour, and used an infrared sensing thermometer to measure the external case temperature. Be very careful about trusting this: you need to do some tricky calibrations to get anywhere near precise when you measure metal surfaces. The easy way, is to put a piece of duc[kt]tape on the metal surface and make sure your thermometer can see only that surface. Unfortunately, the tape will also act as insulation, so the result you get is not precise even then. It got up to 48 C externally in the physics package area. That's quite normal. Those small Rb's keep the internal temperature constant using heaters, which can raise the temperature and by being able to dump excess heat through their heat-sink to lower the temperature. You shouldn't run your Rb too hot, as this decreases the electronics lifetime and reduces the wiggle-room of the thermal management inside the device. On the other hand, cooling it too much will only increase the power drain for the heaters and increase the thermal gradients inside the unit, likely degrading thermal stability. 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] FE-5680A heat sink
Hi Poul, By replying to my reply to Leigh, and clipping out everything that I wrote (but my name), you seem to be attributing to me, what Leigh wrote. You then rephrased my statement about heaters in the physics package, restated my statement about extra cooling increasing the power drawn by the heaters. You then clarified things greatly by advising to not run the Rb too hot, but also don't cool it too much. ??? If you have so much to say to the original author, and nothing to say about my reply, wouldn't it have been be better to just reply to his message, instead of mine? -Chuck Harris Poul-Henning Kamp wrote: In message 4a2cfce2.5020...@erols.com, Chuck Harris writes: I ran the device today for about half an hour, and used an infrared sensing thermometer to measure the external case temperature. Be very careful about trusting this: you need to do some tricky calibrations to get anywhere near precise when you measure metal surfaces. The easy way, is to put a piece of duc[kt]tape on the metal surface and make sure your thermometer can see only that surface. Unfortunately, the tape will also act as insulation, so the result you get is not precise even then. It got up to 48 C externally in the physics package area. That's quite normal. Those small Rb's keep the internal temperature constant using heaters, which can raise the temperature and by being able to dump excess heat through their heat-sink to lower the temperature. You shouldn't run your Rb too hot, as this decreases the electronics lifetime and reduces the wiggle-room of the thermal management inside the device. On the other hand, cooling it too much will only increase the power drain for the heaters and increase the thermal gradients inside the unit, likely degrading thermal stability. Poul-Henning ___ 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] Datron 4910 service manual request
Does anyone has a service manual for the Datron / Wavetek 4910 voltage standard. The output voltage is correct. I have problems with battery power. Met vriendelijke groeten, Regards, ing. Frans de Haan Haarlem the Netherlands ___ 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] FE-5680A heat sink
In message 4a2d129c.3060...@erols.com, Chuck Harris writes: If you have so much to say to the original author, and nothing to say about my reply, wouldn't it have been be better to just reply to his message, instead of mine? What can I say ? It was early in the morning ? See also: my .sig :-) 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] FE-5680A thermal management
Leigh, I agree with Chuck. I have both an FE-5650A and an FE-5680A. With the former I was concerned about the heat, and so ran it only for short periods, until I understood what was going on. I had the impression from the data sheet that there were different heatsink options for different temperature ranges, and I now believe this led me astray. With the FE-5680A I had the opportunity to study things in more detail. There is no temperature range specification that I could find, and no particular advice in the manual regarding installation. I ran the unit from regulated 15V DC, and monitored the supply current. With no extra cooling, the steady state current was about 700mA. With air blown over it, the current increased. With the unit placed in a poly bag, the current decreased to about 650mA. By the way, the current also decreased when operated from 17V DC. This tells me that the whole structure is part of the thermal package, and we should not attempt to force down the case temperature just because the unit runs hot. My experience with high performance OCXOs tells me that the thermal environment is carefully designed, and part of the calibration process - if you modify this environment (by cooling or extra insulation) you modify the thermal environment, and are at risk of modifying the performance. I'd leave well alone, and run the unit in an open, breeze-free environment. 73, Murray ZL1BPU ___ 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] FE-5680A thermal management
In message be50c3a72eba61449c804b2c8b4ae38101ebb...@neptune.rakon.net, Murra y Greenman writes: With the FE-5680A I had the opportunity to study things in more detail. The PRS10 manual has some good info. -- 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] FE-5680A heat sink
Hi Poul, I have long espoused that one should never attribute to malice that which can be more easily explained by ignorance. So, I didn't believe malice was involved. I just found your post curious, that's all. I'm pretty sure that mornings should be banned. -Chuck Harris Poul-Henning Kamp wrote: In message 4a2d129c.3060...@erols.com, Chuck Harris writes: If you have so much to say to the original author, and nothing to say about my reply, wouldn't it have been be better to just reply to his message, instead of mine? What can I say ? It was early in the morning ? See also: my .sig :-) Poul-Henning ___ 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] FE-5680A heat sink
In message: 4a2d60a2.3030...@erols.com Chuck Harris cfhar...@erols.com writes: : I'm pretty sure that mornings should be banned. Perty much... Nobody has a breathalizer to ensure that you are sufficiently caffeinated to give a good chance of a coherent reply :) Lord know that would have saved me much embarrassment over the years... However, since this is time-nuts, and we do deal with things on the hairy edge of what is possible, I'm sure someone will point to a side project that they've done that does just this, with schematics available for download form their web site :) 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] FE-5680A thermal management
In message be50c3a72eba61449c804b2c8b4ae38101ebb...@neptune.rakon.net, Murray Greenman writes: With the FE-5680A I had the opportunity to study things in more detail. The PRS10 manual has some good info. -- 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. Ok, hope everyone can see what above was written by Poul and Murray respectively. ;-) For the FRS-C read page 7 (chapter 2.4 Mounting in the below manual. http://www.to-way.com/frs.pdf It says the base plate should never go above 65 deg C. -- Björn ___ 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] Datron 4910 service manual request
I'd like to find a copy, too. Same problem, and there doesn't seem to be replacement batteries that are fit-and-form equivalents. Thanks, Steve On Mon, Jun 8, 2009 at 3:35 PM , Frans wrote: Does anyone has a service manual for the Datron / Wavetek 4910 voltage standard. The output voltage is correct. I have problems with battery power. Met vriendelijke groeten, Regards, ing. Frans de Haan Haarlem the Netherlands ___ 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] FE-5680A thermal management
- Original Message - From: Murray Greenman murray.green...@rakon.com To: time-nuts@febo.com Sent: Tuesday, June 09, 2009 6:42 AM Subject: [time-nuts] FE-5680A thermal management Leigh, I agree with Chuck. I have both an FE-5650A and an FE-5680A. With the former I was concerned about the heat, and so ran it only for short periods, until I understood what was going on. I had the impression from the data sheet that there were different heatsink options for different temperature ranges, and I now believe this led me astray. With the FE-5680A I had the opportunity to study things in more detail. There is no temperature range specification that I could find, and no particular advice in the manual regarding installation. I ran the unit from regulated 15V DC, and monitored the supply current. With no extra cooling, the steady state current was about 700mA. With air blown over it, the current increased. With the unit placed in a poly bag, the current decreased to about 650mA. By the way, the current also decreased when operated from 17V DC. This tells me that the whole structure is part of the thermal package, and we should not attempt to force down the case temperature just because the unit runs hot. My experience with high performance OCXOs tells me that the thermal environment is carefully designed, and part of the calibration process - if you modify this environment (by cooling or extra insulation) you modify the thermal environment, and are at risk of modifying the performance. I'd leave well alone, and run the unit in an open, breeze-free environment. 73, Murray ZL1BPU Murray et al, The package of both units is clearly meant to be mounted on something-the real question is how much heat sinking would that something have provided? Changing the external heatsinking to achieve the nominal supply current at the nominal supply voltage would appear to be the only simple way to operate the units as intended. I've not gone through this exercise yet with the 5650, but I suspect the amount of heatsinking used is not that critical. Using a variable speed fan to determine the 'correct' mounting plate temperature (corresponding to nominal supply current/voltage) might be a good way to start. The design of a heatsink to achieve the same base plate temperature should be a trivial exercise. Constraining the 'ambient' air temperature to an appropriate range in the vicinity of the unit should certainly help as well. Regards DaveB, NZ ___ 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] Datron 4910 service manual request
I have a manual, but it's hard-copy and LARGE. If you can narrow down your problem area, I'd be happy to scan some schematics. I also have two 4910's; I can probe some test points if you need some values. Bill Ezell -- They said 'Windows or better' so I used Linux. Steve Krull wrote: div class=moz-text-flowed style=font-family: -moz-fixedI'd like to find a copy, too. Same problem, and there doesn't seem to be replacement batteries that are fit-and-form equivalents. Thanks, Steve On Mon, Jun 8, 2009 at 3:35 PM , Frans wrote: Does anyone has a service manual for the Datron / Wavetek 4910 voltage standard. The output voltage is correct. I have problems with battery power. Met vriendelijke groeten, Regards, ing. Frans de Haan Haarlem the Netherlands ___ 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. /div ___ 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] FE-5680A thermal management
Almost all rubidium standards DO specify the use of some form of a heat sink. For the FRK and M100 units this can be a heat sink with around 1 fins or just bolted to a metal plate or chassis. The military freq standard that had M100's in them had the unit mounted to a 5x5x.2 aluminum plate that was in turn bolted to the chassis. My Efratom PTB-100 time bases for the Tektronix TM500 mainframes have a large heat sink mounted to a FRK style oscillator. LPROs are supposed to be mounted to a metal chassis (they usually come with a thermal pad attached to them). I have seen them lose lock in free air. I saw one mounted in a piece of cell phone equipment. It was bolted to a large heat sink that formed most of the front of the enclosure. I have also seen FE-5680A's in their native habitat (again, cell phone equipment). They were mounted to a thick (1/8?) PCB around 6x16. The side of the PCB that the 5680 was bolted to had a solid ground plane. The 5650A's had one side bolted to a metal chassis. _ Hotmail® has ever-growing storage! Don’t worry about storage limits. http://windowslive.com/Tutorial/Hotmail/Storage?ocid=TXT_TAGLM_WL_HM_Tutorial_Storage_062009 ___ 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] FE-5680A heat sink
Chuck, This device is a pull from a larger system, probably a cell site. It's clearly designed to be mounted on something, as it has lots and lots of holes around the edge. I suspect there's some thermal management that's missing. The FEI sheet gives typical data for the 0-50C range, though presumably that's ambient temperature. I don't want to cool the physics package per se, but I do want to at least approximate what kind of thermal solution ought to be supplied. Quite a few of these have been sold, and I've gotten good advice from others on this list about calibration. I'd hoped that someone would have experience with the thermal management. So far I've seen http://www.dd1us.de/Downloads/precise%20reference%20frequency%20rev%200_4.pdf which shows (but doesn't describe) a heat sink on the bottom. Leigh. I'm puzzled. I admit that I don't have a lot of experience with Rb standards, but I do have a bit of experience with the HP-5065A Rb standard. In the 5065A, the entire physics package is enclosed in an oven. Assuming that your Rb is the same, and I believe it is, your plan to force the physics package to run at room temperature is just going to make the oven work harder in its never ending quest to maintain stable temperature. If you monitor the current draw of the 5680A, you will probably see that it goes up when you put a fan on it. Sometimes, you just have to let electronics run hot. What did the manufacturer suggest? -Chuck Harris Leigh L. Klotz, Jr WA5ZNU wrote: I've attached an SMA connector to my FE-5680A and built an external linear power supply with a TO-3 7815. I ran the device today for about half an hour, and used an infrared sensing thermometer to measure the external case temperature. It got up to 48 C externally in the physics package area. I put a muffin fan on top and it brought it down to 38C but I don't think this is a good plan because I worry about the effects of the fan's magnetic field on the Rubidium system. I found in my junk box a finned Aluminum heat sink that's exactly the same size as the FE-5680A and plan to tap it around the edges for 4-40 hardware to attach to the many screw holes. Even so, this heat sink will be on the bottom, so the FE-5680A will have to be operated upside down for this to help. Has anybody got good thermal management solution for this device? This is the one currently selling on eBay in the 25x88x125mm chassis. Thanks, Leigh. ___ 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. 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] FE-5680A heat sink
Calm down Chuck, your doing it again. 2009/6/9 Chuck Harris cfhar...@erols.com: Hi Poul, By replying to my reply to Leigh, and clipping out everything that I wrote (but my name), you seem to be attributing to me, what Leigh wrote. You then rephrased my statement about heaters in the physics package, restated my statement about extra cooling increasing the power drawn by the heaters. You then clarified things greatly by advising to not run the Rb too hot, but also don't cool it too much. ??? If you have so much to say to the original author, and nothing to say about my reply, wouldn't it have been be better to just reply to his message, instead of mine? -Chuck Harris Poul-Henning Kamp wrote: In message 4a2cfce2.5020...@erols.com, Chuck Harris writes: I ran the device today for about half an hour, and used an infrared sensing thermometer to measure the external case temperature. Be very careful about trusting this: you need to do some tricky calibrations to get anywhere near precise when you measure metal surfaces. The easy way, is to put a piece of duc[kt]tape on the metal surface and make sure your thermometer can see only that surface. Unfortunately, the tape will also act as insulation, so the result you get is not precise even then. It got up to 48 C externally in the physics package area. That's quite normal. Those small Rb's keep the internal temperature constant using heaters, which can raise the temperature and by being able to dump excess heat through their heat-sink to lower the temperature. You shouldn't run your Rb too hot, as this decreases the electronics lifetime and reduces the wiggle-room of the thermal management inside the device. On the other hand, cooling it too much will only increase the power drain for the heaters and increase the thermal gradients inside the unit, likely degrading thermal stability. Poul-Henning ___ 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. -- Steve Rooke - ZL3TUV G8KVD JAKDTTNW A man with one clock knows what time it is; A man with two clocks is never quite sure. ___ 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] FE-5680A heat sink
Hi Leigh, I just looked at a manual for an EGG Rb standard module, and their spec is for -55C ambient to +68C baseplate. They had another spec that said MTBF 90,000 hours at 40C baseplate. Your FEI unit probably has a similarly worded spec. To me this means that the ideal (expected) temperature for the baseplate is 40C. If you are intending to operate your Rb block in a home environment, that has conditioned air, you can assume that the ambient temperature will be nominally 25C. I would start from that point, simply attach the block to the chassis, and measure the operating temperature of the baseplate. If it is around 40C, great! If it is much above 40C, you might want to add a heatsink. I wouldn't go out of my way to get below 40C. You can calculate the heatsink size knowing only the ambient temperature, and the power demand of the Rb block. But for operation in a civilized area, it is easier just to try a simple experiment. -Chuck Harris Leigh L. Klotz, Jr WA5ZNU wrote: Chuck, This device is a pull from a larger system, probably a cell site. It's clearly designed to be mounted on something, as it has lots and lots of holes around the edge. I suspect there's some thermal management that's missing. The FEI sheet gives typical data for the 0-50C range, though presumably that's ambient temperature. I don't want to cool the physics package per se, but I do want to at least approximate what kind of thermal solution ought to be supplied. Quite a few of these have been sold, and I've gotten good advice from others on this list about calibration. I'd hoped that someone would have experience with the thermal management. So far I've seen http://www.dd1us.de/Downloads/precise%20reference%20frequency%20rev%200_4.pdf which shows (but doesn't describe) a heat sink on the bottom. Leigh. ___ 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] FE-5680A heat sink
Leigh L. Klotz, Jr WA5ZNU wrote: Chuck, This device is a pull from a larger system, probably a cell site. It's clearly designed to be mounted on something, as it has lots and lots of holes around the edge. I suspect there's some thermal management that's missing. The FEI sheet gives typical data for the 0-50C range, though presumably that's ambient temperature. I don't want to cool the physics package per se, but I do want to at least approximate what kind of thermal solution ought to be supplied. Several years back I bought a 5680A and mine came still mounted on the original (Lucent?) circuit board. There is a small amount of circuitry on one end, but most of the large board is just a solid plated area where the FE-5680A mounts. This is almost 100 in^2 plated on both sides, so an equivalent would be a sheet of aluminum about 7.25 x 13.5 inches. I'll let someone else translate that to an appropriate finned heatsink. Quite a few of these have been sold, and I've gotten good advice from others on this list about calibration. I'd hoped that someone would have experience with the thermal management. So far I've seen http://www.dd1us.de/Downloads/precise%20reference%20frequency%20rev%200_4.pdf which shows (but doesn't describe) a heat sink on the bottom. Leigh. I never saw that particular pdf article before. It looks interesting. The 5680A I got was a bit different from most and I never found a way to program mine. I'll have to revisit the unit and see if the header connector he used works. I though I looked at that, but it has been a long time. Worth another attempt, I guess. -Rex, kk6mk I'm puzzled. I admit that I don't have a lot of experience with Rb standards, but I do have a bit of experience with the HP-5065A Rb standard. In the 5065A, the entire physics package is enclosed in an oven. Assuming that your Rb is the same, and I believe it is, your plan to force the physics package to run at room temperature is just going to make the oven work harder in its never ending quest to maintain stable temperature. If you monitor the current draw of the 5680A, you will probably see that it goes up when you put a fan on it. Sometimes, you just have to let electronics run hot. What did the manufacturer suggest? -Chuck Harris Leigh L. Klotz, Jr WA5ZNU wrote: I've attached an SMA connector to my FE-5680A and built an external linear power supply with a TO-3 7815. I ran the device today for about half an hour, and used an infrared sensing thermometer to measure the external case temperature. It got up to 48 C externally in the physics package area. I put a muffin fan on top and it brought it down to 38C but I don't think this is a good plan because I worry about the effects of the fan's magnetic field on the Rubidium system. I found in my junk box a finned Aluminum heat sink that's exactly the same size as the FE-5680A and plan to tap it around the edges for 4-40 hardware to attach to the many screw holes. Even so, this heat sink will be on the bottom, so the FE-5680A will have to be operated upside down for this to help. Has anybody got good thermal management solution for this device? This is the one currently selling on eBay in the 25x88x125mm chassis. Thanks, Leigh. ___ 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] FE-5680A heat sink
Also see my post from June of last year where I had measured the heat sink rise over ambient of several rubidium oscillators in free air... the FEI-5650 was very close to it's operating limit if operated in free air and not attached to something: http://www.febo.com/pipermail/time-nuts/2008-June/031695.html _ Lauren found her dream laptop. Find the PC that’s right for you. http://www.microsoft.com/windows/choosepc/?ocid=ftp_val_wl_290 ___ 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] FE-5680A heat sink
Hi, some light might be shed on the heatsink problem by reading the data sheet for the LPRO 101 (Symmetricom) The units will have similar issues to cope with. The LPRO has temperature controlled lamp and filter, at different temperatures above 80C. Its power consumption is shown in a chart and is reduced as the temperature rises because the heating power needed becomes less. It must have a 17V internal series regulator, because total power consumption falls down to the minimum of 18V. MTBF is listed as 380kh at 20C, 320kh at 30C, 253kh at 40C, 189k at 50C and 134k at 60C. These are values that you would expect for most solid state boards. My solution was to put the device onto a finned heat sink in an aluminum box with a tiny 12V brushless fan, (40mm) which runs on 8 volts and is switched by a thermistor in the heatsink to keep the baseplate at 40C. This seems to be a good trade-off with MTBF, and the 10 MHZ xtal will run at a constant temperature of 40C + or - 0.05. I have not yet assembled the gear to measure how much its performance is improved. cheers, Neville Michie On 09/06/2009, at 2:18 PM, Mark Sims wrote: Also see my post from June of last year where I had measured the heat sink rise over ambient of several rubidium oscillators in free air... the FEI-5650 was very close to it's operating limit if operated in free air and not attached to something: http://www.febo.com/pipermail/time-nuts/2008-June/031695.html _ Lauren found her dream laptop. Find the PC that’s right for you. http://www.microsoft.com/windows/choosepc/?ocid=ftp_val_wl_290 ___ 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.
