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The procedure for doing the *measurement* of # decades has been well
described in a few FCSC handouts; even in their "Catalog: Fluorescent
Microbead Standards". It's just a matter of running a mixture of
their calibrated "Quantum" beads and plotting # molecules vs. channel
number on semi-log graph paper. If you extrapolate the (hopefully
straight) line to channels 1 and 256 (or 1024) you can read off the #
decades.
Doing something about it is harder: On the FACStar+ it's not too bad;
there are screwdriver holes on the front edges of the logamp cards
marked "G" for parameters 2, 3, 6 and 7. For the other parameters you
need to guess which of the rectangular blue trimpots to tweak. Just
keep tweaking and measuring until you get 4 decades exactly. It is
helpful to remember that, once you have established that your calibration
points lie on a straight line, you only need to monitor the *distance in
channels between 2 widely spaced peaks* as you continue to tweak; you
don't need to plot the graph each time.
For the FACScan I can't help. For ours we just *measured* the
characteristic without trying to *change* it. I wonder if B_D
service personel would help with this kind of exercise??
Regards, | | < Frank: battye@wehi.edu.au
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