Re: [time-nuts] FE-5680A heat sink
http://www.ham-radio.com/wa6vhs/Test%20equipment/FREQUENCY%20STANDARDS/FE-5680A/fei%205680a.pdf has high quality images of the 5680A and 5650A internal electronics. Bruce 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. ___ 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 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. If the case is Mu metal or similar then the modification shown in the above article will likely destroy its magnetic shielding properties (unless its annealed in a hydrogen atmosphere at 400C for several hours after machining). The unit is designed like competitive units to be bolted to a heatsink or panel. The trick being to maintain the baseplate temperature within the specified temperature range (-5C to +50C). Since the power dissipation is low (11W @ 25C) you wont need an extremely low thermal resistance heatsink unless your ambient temperature is relatively high. If the ambient temperature is 40C then a 1C/W heatsink should maintain the base plate temperature below 60C. Just mount the 5680A on your heatsink and monitor the steady state heatsink temperature (with a thermocouple, RTD or other contact thermometer - could even use photochromic temperature sensing strips) both with the FE5680A upside down and the right way up. The infrared thermometer is unreliable unless its reading is corrected for the emissivity of the target in the 20um infrared region. Bruce 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. ___ 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 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. If the case is Mu metal or similar then the modification shown in the above article will likely destroy its magnetic shielding properties (unless its annealed in a hydrogen atmosphere at 400C for several hours after machining). The unit is designed like competitive units to be bolted to a heatsink or panel. The trick being to maintain the baseplate temperature within the specified temperature range (-5C to +50C). Since the power dissipation is low (11W @ 25C) you wont need an extremely low thermal resistance heatsink unless your ambient temperature is relatively high. If the ambient temperature is 40C then a 1C/W heatsink should maintain the base plate temperature below 60C. Just mount the 5680A on your heatsink and monitor the steady state heatsink temperature (with a thermocouple, RTD or other contact thermometer - could even use photochromic temperature sensing strips) both with the FE5680A upside down and the right way up. The infrared thermometer is unreliable unless its reading is corrected for the emissivity of the target in the 20um infrared region. Bruce 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. ___ 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
I think we've all learned from this. Good info about the Efratom unit, and sounds as though we should aim for around 38C with the FEI units as well. The FE-5680 looks to be easier to deal with than the FE-5650, so I'll look into that first. 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 heat sink
Murray Greenman wrote: I think we've all learned from this. Good info about the Efratom unit, and sounds as though we should aim for around 38C with the FEI units as well. The FE-5680 looks to be easier to deal with than the FE-5650, so I'll look into that first. 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. For those who haven't found it here is a link to a manual for one version of the 5680A: http://www.ham-radio.com/wa6vhs/Test%20equipment/FREQUENCY%20STANDARDS/FE-5680A/5680%20TECH%20MANUAL.pdf Bruce ___ 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
Yes, thank you to all. I'll go ahead with the heat sink on the bottom and consider a fan nearby. Leigh/WA5ZNU I think we've all learned from this. Good info about the Efratom unit, and sounds as though we should aim for around 38C with the FEI units as well. The FE-5680 looks to be easier to deal with than the FE-5650, so I'll look into that first. 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. ___ 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
Bruce, Thank you for this point. I've seen Mu metal competitors but I can't tell what the case is made from. Pretty much everybody I've seen on this has had to make some kind of allowance for getting the RF out. I drilled a hole for an SMA connector and had it exit on the digital half of the chassis (not the physics half), as they're separated by a very large bar, perhaps brass. It has a few ways to get wires through, but it didn't seem to be a good idea. The SMA is a jumper I bought on eBay from a Chinese manufacturer, with an IPX connector on one end and the SMA bulkhead on the other. Hirose U.Fl and IPX are said to be compatible, but it didn't look like it wanted to stay down, so I tacked a wire to the head of the IPX connector put a brass 2-54 nut on a nearby post to ensure mechanical connection. I think this is better than soldering open coax to the connector, but given the short size and low frequency (10 Mhz) it's probably not a concern. So, I probably did something bad to the magic Mu metal annealing by drilling a hole, but it's as far as I could get over on the digital side of the brass divider. At this point I have nothing calibrated that I can measure the device with and see if there's any small magnetic influence, but perhaps someday I will, or maybe someone else would like to compare with another device sometime. It might have been possible to re-purpose a pin from the existing RS232 connector, and perhaps others who buy this same run of device may want to investigate that. Leigh. Bruce Griffiths wrote: Leigh L. Klotz, Jr WA5ZNU wrote: So far I've seen http://www.dd1us.de/Downloads/precise%20reference%20frequency%20rev%200_4.pdf If the case is Mu metal or similar then the modification shown in the above article will likely destroy its magnetic shielding properties (unless its annealed in a hydrogen atmosphere at 400C for several hours after machining). ___ 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
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.
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.
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 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.
