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-John ============== > Hi > > The big hitters for heat outside the physics package seem to be the RF > excitation and the microwave generation "stuff". The regulators will warm > things up if you run high voltage into them, but I would probably not do > that. > > I don't believe that putting multiple swimming pools into the basement, > mercury filled or otherwise was ever a real candidate for a solution. It > is kind of interesting to see just how big the "jug of water" would have > to be. > > Right now my leading candidate is a multi layer aluminum / steel enclosure > with a "point short" between each of the layers to keep the heat rise > under control. Cool the "baseplate" with recirculating water and a cheap > (< $50) pump. Throw in a fan and radiator to cool the water to room > temperature. Servo the temperature with "what ever" at the point shorts. > Monitor the temperature as best you can. > > The main "what ever" still in there are TE coolers. A quick look suggests > that +12 heats and -12 cools. In between the two it's not clear that much > happens (maybe it does ...). Even if it does not, I haven't dug deep > enough to see if something like current drive takes care of the dead band > issue. > > Some math. It's late, but I think this is about right: > > 1) 4 layers > 2) Shorts at 2 C/W > 3) 10 W "inside" > 4) 80 C heat rise - not going to work > > If I stick with 4 layers, 10 W, and a 15 C rise then the shorts need to be > ~ 0.38 C/W. A 15C rise gets me to 40C which looks reasonable based on the > app notes I have read on the rubidiums. > > If the basement moves up 5 C then I'm cold pumping 1/3 of the 10W. Same > thing in reverse if the basement drops 5 C. Both are unlikely to happen as > long as there isn't a catastrophic failure of the HVAC. > > If I go to a air cooled baseplate heat sink, it's thermal resistance is > going to have to come out of the budget. My *guess* is that's going to be > more involved than a simple pump and some plastic tubes. > > Bob > > On Dec 24, 2009, at 10:46 PM, Hal Murray wrote: > >> >> li...@cq.nu said: >>> The original intent was to simply take an existing "cheap" rubidium >>> and do simple things to it. Tearing it into pieces and redesigning >>> parts of it was not anything I originally contemplated. The tight >>> integration of the physics package to the electronics would make this >>> a fairly involved process. >> >> Sure, but if we are discussing digging a hole big enough for a ton of >> mercury, then taking apart a tightly integrated package seems worth >> considering. >> >> I expect the packaging might be reasonable for this purpose. After all, >> the >> designers probably wanted to keep that heat away from the electronics. >> >> >> >> -- >> 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. >> > > > _______________________________________________ > 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.