Pmt Preamp Block Diagram - Teledyne T200H User Manual

Teledyne API - Model T200H/T200M Operation Manual
07270D DCN7141
hence, the signal from the PMT. Secondly, the gain of the amplified signal can further be
adjusted through a potentiometer. These adjustments should only be performed when
encountering problems with the software calibration that cannot be rectified otherwise.
See Section 11.6.3.8 for this hardware calibration.
O Test Control
From CPU
PMT
Coarse
Gain Set
(Rotary
O Test
LED
PMT HVPS
To
Drive Voltage
Motherboard
PMT Output
E Test Control
From CPU
PMT Temp Analog Signal
to Motherboard
PMT Temp
Sensor
TEC Control
PCA
Figure 8-19:
The PMT temperature control loop maintains the PMT temperature around 7° C and can
be viewed as test function PMT TEMP on the front panel (see Section 6.2.1).
The electrical test (ETEST) circuit generates a constant, electronic signal intended to
simulate the output of the PMT (after conversion from current to voltage). By bypassing
the detector's actual signal, it is possible to test most of the signal handling and
conditioning circuitry on the PMT preamplifier board. See section 6.9.6 for instructions
on performing this test.
The optical test (OTEST) feature causes an LED inside the PMT cold block to create a
light signal that can be measured with the PMT. If zero air is supplied to the analyzer, the
entire measurement capability of the sensor module can be tested including the PMT and
the current to voltage conversion circuit on the PMT preamplifier board. See section
6.9.5 for instructions on performing this test.
PMT Preamp PCA
O-Test
Generator
PMT Fine
Gain Set
(Rotary
Switch)
D-A
Converter
Amp to
Voltage
Converter/
Amplifier
MUX
E-Test
Generator
PMT
Temperature
Feedback
Circuit
PMT Output Signal
(PMT) to Motherboard

PMT Preamp Block Diagram

Principles of Operation
Low
Pass Noise
Filter
PMT
Signal
Offset
293