Dear confocalists,

Biorad is selling a PMT upgrade for MRC-600 users that will upgrade to the
type of PMTs used in the MRC-1000 (a design that enhances performance by
allowing multiple reflections of an incoming photon and increasing the
probability of it's absorbance, as I understand it). The specifications
claim a 1.7 - 2.0 increase in "sensitivity". There has been some
back-pedaling on these written specs, conditioned by the fact that the the
MRC-600 has a lower voltage HV supply and thus will not show this degree of
improvement.

I have requested several times (from various Biorad personel) the
technical specs of these new tubes so that we could try to make an
educated choice, but I have never received any specifications. I am
interested in such things as the plots of spectral sensitivity, dark
current vs cathode voltage, gain vs cathode voltage, or in a pinch, did
they make your life better.

I am not trying to rough-up Biorad. We like our system. I'm sure all
companies, systems and software have their little quirks (as I do also). I
don't care where this information comes from (in case Biorad is listening)
but hope that someone can help us out. We have the money allocated and
really want to make the purchase. Biorad has offered this with a
money-back guarantee of satisfaction, but I just feel responsible for
knowing a bit more about the product before making such a purchase.

Thanks in advance for any help you can provide.


Sincerely,

Dale A. Callaham
Central Microscopy Facility
University of Massachusetts
Amherst, MA 01003 USA

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