From: Philo, John <jphilo@amgen.com>
  To  : 'RASMB@BBRI.HARVARD.EDU' <RASMB@BBRI.HARVARD.EDU>
  Date: Tue, 21 Jan 1997 08:07:54 -0800

RE: XL-I noise

Hans,

I don't think anyone is going to be able to answer your query without a
better description of the problem.  What is the nature and magnitude of
the noise?  Are you talking about essentially random deviations from one
radius to the next, or noise that persists over a range of radii?  Is it
repeatable from scan to scan?  Does it occur when you scan an empty
rotor hole? 

Also, there are significant differences between versions of the data
acquisition software, with newer versions reducing some sources of
noise.  You need to say what version you are using.

'Best,

John Philo

>----------
>From: 	Hans T.H. Beernink[SMTP:hbeernin@protein.med.uvm.edu]
>Sent: 	January 21, 1997 7:35 AM
>To: 	RASMB@BBRI.HARVARD.EDU
>Subject: 	XL-I noise
>
>Dear RASMBers, 
>
>I'm running into a problem that seems to be common for XL-I users.  That
>is, noise in the FFT scans when using the Rayleigh system.  I'm aware that
>the low resonance from the frame of the instrument can interfere, but 
>we've (supposedly) reduced that by dampening the diffusion pump.  The 
>noise is most visible during equilibrium scans.  
>
>Has anoyone else run into similar difficulties, and if so, what solutions 
>are around?
>
>Thanks, 
>Hans
>_____________________________________________________________________________
>Hans T.H. Beernink, Department of Biochemistry, University of Vermont
>
>hbeernin@protein.med.uvm.edu			FAX (802)862-8229 
>hbeernin@zoo.uvm.edu				Tel.(802)656-8244
>
>