[RASMB] Radius Out of Range?

[John Philo]

Peter, when you try to do a radial calibration you have to be careful about
having too high an OD in the hole opposite the counterbalance (hole 2 in
your case), and having a 6-channel cell there rather than a 2-channel can
also cause problems. This situation arises because once you clear the radial
calibration the instrument must try to do the delay calibration using hole
2, since it no longer knows how to find the very restricted holes
(restricted radially) in the counterbalance. It really expects to find a
2-channel cell in hole 2, and it tries to do the delay calibration at 6.5
cm. The problem here might be that the OD of your solutions in Channel B of
cell 2 is too high so it can't find the center rib, or the 'default' radial
calibration is so far off that when it thinks it is at 6.5 cm the light is
actually hitting the Epon resin in between channels A and B or between B and
C.
 
This will always be true unless you have done a delay calibration before you
ask for the radial calibration. That is, you can avoid this problem by first
doing some sort of scan (setting the delay), and then asking for a radial
calibration.
 
Also be sure you haven't accidentally left the 400 nm cutoff filter in place
or at an in-between position.
 
You could temporarily put an empty 2-channel cell in hole 2 and use that to
do the radial calibration, then go back to your 6-channel cell.
 
John
  _____  

From: rasmb-bounces at rasmb.bbri.org [mailto:rasmb-bounces at rasmb.bbri.org] On
Behalf Of Peter Edward Prevelige Jr
Sent: Thursday, September 01, 2011 1:27 PM
To: rasmb at rasmb.bbri.org
Subject: [RASMB] Radius Out of Range?



Hi All

 

I am having a host of problems trying to get a run going. They are centered
around radius problems and delay calibration. 

 

Right now, I am trying to do a single scan of 3 cells at 280 nm in the 4
hole rotor, 3K RPM, 6 sector cells. I selected the option to do a radial
calibration and it is giving me radius out of range errors. I have checked
the counterbalance and it is installed properly. This is the second
counterbalance I've tried and as far as I know they were both working fine
previously. 

 

Can anyone tell me what I might try to get this sorted out?

 

Thanks

 

Peter

 

 

 

 

Peter E. Prevelige Jr.

Professor

Dept. of Microbiology, BBRB 416/6

Univ. of Alabama @ Birmingham

845 19th St. South

Birmingham AL. 35294-2170

Phone 205 975-5327

FAX 205 975-5479

prevelig at uab.edu

http://www.microbio.uab.edu/faculty/prevelige/prevelige-p.htm

 

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