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Re: temperature jumps



dQ = 0, dT = 4 degrees....sounds like a phase transition to me. Better
write it up quick. Check the slope. Is it 1st or 2nd order?...smile, Karl

I had a similar problem as a grad student. The heater timer used relay
contacts to turn on the heater. The contacts would occasionally stick,
causing the heater to stay on longer than the preset time. Voila, phase
transition! Of course, it would not repeat at the same temperature. I sure
learned that it pays to analyze your data promptly rather than take lots of
data to be analyzed later. One years worth of useless info... I'm betting
on similar causes. Karl


Every now and then a section of the curve is displaced upwards. For a period
of about 5 minutes the temperatures recorded are about 4 degrees higher,
then they drop back down to be once again consistent with earlier
measurements. Obviously a measurement problem. Does anyone know what
causes it?


I've seen behavior like that as well, and it was always due to an equipment
problem. Do all of your rigs do this, or just one? It sure sounds like a bad
connection somewhere. Another possibility is interference on the serial line.

JEG
__________________________________

John E. Gastineau john@gastineau.org KC8IEW
900 B Ridgeway Ave. http://gastineau.home.mindspring.com
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Dr. Karl I. Trappe Desk Phone: (512) 471-4152
Physics Dept, Mail Stop C-1600 Demo Office: (512) 471-5411
The University of Texas at Austin Home Phone: (512) 264-1616
Austin, Texas 78712-1081