Peter, My TB is running continuously during months. It draws about 7 W using the black PWR-supply proposed by Tom (TvB). In the room at about 22 °C it does show 32.43 °C, I never passed 37 °C. So I would propose to net go beyond the 40 °C internal temp. reading. I will manufacture a wooden box with thick walls to stabilize the temp. Wood does of course not shield, but because the high thermal capacitance together with its isolation (moderate)it should result in a long thermal constant. Of course the temperature will come up, hopefully not surpassing 42 °C. Low temperature = longer lifetime. Your osc. Adev values are similar to mine, that should be ok (good). I can confirm the experience by Warren. I use 490 s,0.68 damp factor and a gain of -3.55 Hz/V actually resulting to
PPS ADEV @ 1 tau 5.096E-11, @ 100 tau 3.05E-11, @ 500 tau 6.43E-12 @ 1000 tau 2.92E-12 Osc. ADEV @ 1 tau 3.39E-09, @ 100 tau 3.45E-11, @ 500 tau 7.05E-12 @ 1000 tau 3.32E-12 read by Lady Heather, which does not mean that these values are exact! This with the original OCXO, perhaps with an external oscillator one could get better results, but I had no luck yet. The PPS does very seldom exceed +- 5 ns, normally it does move just around +- 2 to 3 ns. The DAC-Voltage changes are in the range of +- 3 steps of around 25µV (a step presesents close to 8 µV) These are my observations, I hope it does help you. regards, Arnold Am 19.08.2010 23:59, schrieb Peter Krengel: > To John WA4WDL: > > The coordinates out of my current (fixed) position calculated by > the SirF GPS and the tbold during a 48h survey are different. > On a map this differences makes up a shift of up to 100m around > my true qth. With other words if I would (and could) use the tbold > as a mobile GPS I would come off road at once ;) > > > To ws: > > Thanks for the interesting answer and tips for modifying factory settings. > > My tbold works in a good stable (temperature) environment. I tried out > to put it in a temp-isolated box but Osc temperature went up to about 50°C > (not too hot?). > > Secondly I tried it without a box at normal 20°C room temperature (varying a > little bit) and it showed OSC 41.75°C. > > What is the better choice? > > It also got fine antenna conditions (mostly 8 sats are recognized having > signals between 38 and 48dBc) by using a roof top ceramic chip antenna (it > has a inner preamp) followed by a 20dB wideband amp and about 20m > coax. As I am located on a hill top it "sees" a 360° free sky down to 0° > elevation. > > I got the following results using factory settings after cold start and 10 > hours running with my true (are they really my true coords?) qth coordinates > saved after self-survey: > > OSC ADEV > 1 tau 2.7E-09 > 10000 tau 7.0E-13 > > My intension (of cause..) is to get the best out of the tbold in short and > long term stability. > > The tbold isnt modified in any way running the original oscillator. > > What do you think ? > > ------------------------------------ > > To Mark: > > I too got a LPRO rubidium but it I'm not very satisfied because of the need > of long time warm up after power fail and the need of a heat sink. > > In addition the tube wont last for ever and is used for 10(?) years... > > Anyway I would like to compare both tbold and Lpro if the tbold is > setup best as possible. > > > Thanks and regards > Peter DG4EK > _______________________________________________ _______________________________________________ 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.