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noise in the PAM fluorometer

Attila Aradi aa_levlista at mailbox.hu
Tue Jun 1 14:29:22 EST 2004

It seems to be a consequence of a ground loop . (Or maybe power 
supply failure.)
In case of ground loop pls.  see the following:
Ground loop problems and how to get rid of them:

If you have any question do not hesitate to ask.

Attila Aradi

abbarnet at dal.ca (ABarnet) wrote in message 
news:<7bad14f2.0405260739.74860979 at posting.google.com>...
>  Help please!
>  I am having serious problems with noise in a PAM 101/102/103
>  fluorometer (Walz).  The normal noise in the signal ranges about +/-
>  0.015V measured at 1.6kHz with the gain/damping/etc settings I'm
>  using.  This goes through a strange low-frequency sinusoidal pattern
>  in the signal followed by an increase in the noise to +/- 0.20V
>  measured at 1.6kHz.  The signal then can either remain noisy, or
>  slowly decrease in noise back to a normal level on a time scale of
>  30min to hours.  This noise comes and goes unpredictably and I can not
>  do anything to induce or get rid of it (ie. wiggle conntections, find
>  breaks in wires, bad grounds, etc.).
>  Has anyone seen this problem before or had similar problems with their
>  instrument?  Any insights?
>  I have ruled out the posibility that it is stray light into the
>  photomultiplier detector.  Also, analysis of the output shows the
>  signal noise is not at a frequency of 60Hz, so I am assuming it is not
>  electronic interfearence, but I have not totally ruled that out.  I am
>  in the process of doing things like replacing the BNC cables and
>  trying to make sure everything is shielded.  I have also verified, by
>  hooking up a chart recorder, that the output to the computer is what
>  the PAM is telling it.
>  Thanks for your input!
>  ---

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