Pmt Preamplifier - Teledyne T200 User Manual

A significant performance characteristic of the PMT is the voltage potential across the
electron multiplier. The higher the voltage, the greater the number of electrons emitted
from each dynode of the electron multiplier, in effect, making the PMT more sensitive and
responsive to smaller variations in light intensity, but also more noisy (this is referred to as
"dark noise").
The gain voltage of the PMT is usually set between 400 V and 800 V.
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This parameter is viewable in the Dashboard as HVPS.
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For information on when and how to set this voltage, see Section 5.7.10.4.
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The PMT is housed inside the PMT module assembly (see Figure 5-20). This assembly
also includes the high voltage power supply required to drive the PMT, an LED used by
the instrument's optical test function, a thermistor that measures the temperature of the
PMT and various components of the PMT cooling system including the TEC.
PMT P
The PMT preamplifier board provides a variety of functions:
• Amplifies the PMT Signal into a useable analog voltage that can be processed by the
motherboard into a digital signal to be used by the CPU to calculate the NO, NO
NOx concentrations of the gas in the sample chamber.
• Supplies the drive voltage for the HVPS.
Includes the circuitry for switching between the two physical ranges.
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• Amplifies the signal output by the PMT Temperature sensor and feeds it back to the
thermoelectric cooler driver PCA. This amplified signal is also sent to the Motherboard
to be digitized and forwarded to the CPU.
Provides the means for adjusting the electronic signal output from the PMT.
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208 Teledyne API T200 NO/NO
REAMPLIFIER
/NO Analyzer with NumaView™ Software
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083730200A DCN7962