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.