Re: VT Unit instability problem
Jim Breeyear (jbreeyea@zoo.uvm.edu)
Wed, 14 May 1997 11:41:41 -0700
numare@cnj.digex.net wrote:
>
> 14 May 1997, Wednesday, 0910 EDT
>
> Dear Spinlanders,
>
> We are experiencing an instability problem with the VT unit attached
> to our Bruker AC-200 NMR system. A proton lineshape test on 10% CHCl3 in
> acetone-d6 results in a temperature shifted multiple of peaks, ranging from
> two to four peaks, for the four pulse experiment. The maximum observed shift
> is about 0.7 Hz. When the air compressor is turned off, much of the problem
> goes away. The magnet sits on compressed air supports.
> The above suggests that a regulator in the compressed air system is
> malfunctioning. Just wondering if anyone else has had a similar experience,
> and, if so, has a solution.
> As always, any useful responses will be collected and posted back to
> the groups.
>
> Thanks and best regards,
> Lawrence
>
> Note: Numare Spectralab will be closed 15-26 May 1997. Responses will be
> reviewed and reposted 27 May 1997
>
> --------------------------------------------------------
> Numare Spectralab, Inc.,
> 10 Summit Avenue, Unit 6, P.O. Box 96,
> Berkeley Heights, NJ, 07922-0096,
> Telephone 908-665-0066
> Telefax 908-464-4192
>
> Name: Lawrence Byrnes
> E-mail: numare@cnj.digex.net (Lawrence Byrnes)
> www: http://www.cnj.digex.net/~numare/
> --------------------------------------------------------
Hi,
Interesting problem. I wonder what type of VT unit you have. At first I
thought maybe the field drift was messing you up but I guess it isnt.
Is the temperature gauge stable? Maybe you have too much air flow. Does
the air compressor supply air only to the supports or does it go to the
VT unit as well. Our VT-2000 works great down to 100k.
Waiting to hear how you solve it. I get multiple peaks if I forget to
turn the drift to zero.
Cheers
--
=======================================
Jim Breeyear Manager Inst. Lab.
Chemistry Dept Cook Building
Univ. of Vermont
Burlington, Vt. 05405
Tel:802-656-0196