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You can usefully change the gains of the PMTs (ie using the voltage
control), sadly the machine will only ratio the "raw" signal before the
electronic amplification, so if you boost the gain electronically or use a
log amplifier, you'll still get a ratio based on the unamplified signal.
EXCEPT (I think) the fine gain control kicks in before the pulse processor
boards, so you can do a bit of tweaking with that.
Notice that you can VIEW the signal amplified how you like, so yes you can
play around with the gains, it's just that the pulse processors aren't fed
by those amplifiers, so you might mislead yourself.
If you need to boost the signal to get it on scale, you could do off-line
ratioing using software, although this does have its pitfalls, and ratioing
log signals is dodgy. If you have a mac you could try a copy of my FCS
file utility (FCS Assistant) from the server below.
Ray
At 3:55 pm -0500 2/6/97, Ken McDonald wrote:
>Hi Flowers,
> My question concerns pH measurment using Snarf and the ratio setup. I
>know that with calcium flux (using indo-1) that your settings have to be
>on linear (gain of 1) for fl4 and fl5(using the facs Vantage).Is this
>also the case for pH ratio measurements which also use a ratio for fl2
>and fl3. Could I play around with the gains instead of leaving them at
>gain 1 for fl2 and fl3.
> Thank you in advance...Ken McDonald
Ray Hicks
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