Odd behaviour with ATM equipped probe. (fwd)

From: Bruker Users Mail <bruker-users-mail@chemistry.mcmaster.ca>
Date: Mon Jan 04 2010 - 16:17:02 EST

Hello folks,

Please find attached the description of an unusual problem with an ATM 
equipped probe.

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---------- Forwarded message ----------
Date: Mon, 14 Dec 2009 15:32:48 -0500 (EST)
From: Markus Hoffmann <mhoffman@brockport.edu>
To: bruker-users-mail-request@chemistry.mcmaster.ca
Subject: subscription request

Dear Bob,

I would like to be added to the bruker-users-mail-request.

My name is Markus Hoffmann. I am an Associate Professor at The College at 
Brockport, Department of Chemistry, a four-year liberal arts college, 
where I keep our Avance 300 NMR instrument running. Our instrument was 
installed in 2005 and runs under Topspin 1.3, patchlevel 8. As accessories 
we have a 24 sample changer and variable temperature. The probe has 
automatic tuning and matching capability and z-gradient coils.

<snip>
  Under ATMM, to check tuning and matching for the X (13C) channel, the 
signal disappears when I hit any of the "right arrow" keys for adjusting 
matching and re-appears when I hit any of the corresponding "left arrow" 
keys. We have a tuning rig here and I observe the same on the oscilloscope 
of our tuning rig. Indeed, a 13C experiment would result in just noise 
when we observe no signal under ATMM but in a normal spectrum when I leave 
ATMM with a signal present. Fortunately, we also have a back-up dual probe 
with which I replaced the ailing broadband probe. No problems here; we 
could run in automation about 100 samples for our organic chemistry course 
without any issues.

All of these observations clearly suggest that there is something faulty 
in the broadband probe. Yet, after having submitted for repair our probe, 
the probe supposedly passed all tests, and a 13C spectrum print-out is 
included in the case of the probe, which did arrive back today. However, 
it behaves just the same as before we submitted it for repair. I observe 
the exact same as described above.

I am baffled. If it is not (really) the probe, and not any pre-amp etc. of 
the console, what else is left to explain this? Did anyone else ever run 
into anything like that?

Thanks in advance for any pointers,

Markus





Markus Hoffmann
Department of Chemistry
The College at Brockport
State University of New York
Phone: (585) 395-5587
FAX: (585) 395-5805
mhoffman@brockport.edu

Received on Mon, 4 Jan 2010 16:17:02 -0500 (EST)