[RASMB] Lamp Assembly

[Jeff Lary]

Tim,
The Beckman procedure for running a noise check is
===================================
Run a windowless double-sector cell in rotor hole #2.  Make a 3K RPM and a
60K RPM run per the parameters
Radial scan                   Yes
Mode:                          Continuous
Number of Averages    1
Step Size                      0.001 cm
Min Radius                   5.80 cm
Max Radius                  7.10 cm
Wavelength 1                190 nm
Wavelength 2                 0 nm
Wavelength 3                 0 nm

The standard deviation should be less than 0.01 for both files, to meet
engineering specifications.  If you obtain a standard deviation greater than
0.01, do a LIGHT INTENSITY CHECK ...

===================================
In order to do the 60K check you need to use an aluminum centerpiece (or one
of Tom Laue's new high speed double sector centerpieces).
===================================

We usually check our machines at 230 nm and 280 nm, at 3K RPM, between 6.0
cm & 7.0 cm, and our standard deviations are on the order of 0.003.  If you
are using an empty cell with windows then I'm not surprised that you have a
noisy scan, but I'm not sure from the wording of your message whether you
have the windows in place or not.

As to the problem with the grate for the fan none of our machines have them
over the fan but I can't remember if they were removed because of
interfering with the lamp housing or if they just never had them.


Jeff Lary
Biotechnology Center Unit-3149
ph: 860-486-5036
fax: 860-486-5005
email: jeffrey.lary at uconn.edu
===========================

----- Original Message -----
From: "Timothy R. Mack" <mack at cabm.rutgers.edu>
To: <jphilo at mailway.com>
Cc: <mack at cabm.rutgers.edu>; <rasmb at rasmb-email.bbri.org>
Sent: Monday, September 22, 2003 5:22 PM
Subject: RE: [RASMB] Lamp Assembly


> --------------------------------------------------------------------------
--------
> The older archived RASMB emails can be found at:
> http://rasmb-email.bbri.org/rasmb_archives
> and current archives at
> http://rasmb-email.bbri.org/pipermail/rasmb/
> Search All the Archives at:
> http://rasmb-email.bbri.org/rasmb_search.html
> --------------------------------------------------------------------------
--------
>
> The standard deviation for our instrument using an empty double sector
> centerpiece taken at 280nm is 0.0117AU (after the slit assembly and lamp
> were cleaned). Is this a value I should be satisfied with?
>
> With regards to my question about the gouge in the lamp assembly, I should
> have been more clear. My thinking was that if the fan gate rubbed up
> against the lamp assembly enough to cause a gouge in it than it could
> cause the lamp to vibrate thus introducing noise. I was just curious if
> any one else has seen this before. It seems to me if the gate is modified
> such that it no longer contacts the assembly then the problem should be
> solved however I just wanted to ask to see if anyone thought that this
> could be a symptom of a more systemic problem. Thank you for your
> responses.
>
> Regards,
> Tim