Thank you very much for the many responses with regard to our problem
with intermittant erratic temperature readings.
The overwhelming majority mentioned the connector between the
temperature sensor cable and the probe. While I have not been able
to reproduce the problem I did find some corrosion whe taking the
connector apart and will be replacing the cable, as that looks like
what was the problem here.
Other possible causes mentioned were interruption of the gas flow, a
cracked thermocouple inside the probe, or extremely high shim
currents.
Thanks again
Holger Foersterling
Dear AMMRLers,
we just had a weird glich in th etemperature contol of our Bruker
DRX500 spectrometer. I was called by a user that the temperature
reading was 600K with a set temperature of 298 K and that the sample
was really hot. When I came down I saw temperature reading of 345 K
continuously dropping towards the 298K set temperature. While I was
watching I saw the temperature reading several times momentarily
jumping up to above 400K and back to a reasonable reading.
Eventually the temperature settled down around 298 K again, and I
could not see any more fluctuations. But it appears to me that there
might be some glitch in the temperature control and it might happen
again with a precious sample inside.
While I have seen outrageous readings whe the wrong temperature
sensor was defined (Thermocouple T vs. BTO2000) this was not the case
here. The user said he did not touch the temperature unit and it was
set to hold 298K.
Has anybody experienced a similar problem before ?
Thanks for any advise
)|(
(o o)
-------------------ooO-(_)-Ooo---------------------------
Frank Holger Foersterling, Ph. D.
Director of NMR laboratories
Department of Chemistry, University of Wisconsin-Milwaukee
http://hal.chem.uwm.edu/nmr/
(holger_at_uwm.edu)
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Phone:(414)-229-5896
Fax:(414)-229-5530
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Received on Fri Apr 29 2005 - 16:03:21 MST