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Instruction Manual
1
Introduction / General Information
1.1
Description
A hot cathode ionization gauge (IG) measures vacuum pressure by ionizing gas atoms and molecules inside the
vacuum region of the gauge transducer and measuring the quantity of ions produced. The measurement of the
resulting ion current is directly proportional to the density of gas inside the gauge transducer therefore
proportional to the pressure. As pressure inside the vacuum system drops, there are fewer ions created and
therefore ion current measured is lower translating to a lower pressure reading.
The InstruTech® IGM401 Hornet™ module provides the basic signal conditioning required to turn a hot cathode
ionization vacuum gauge into a complete measuring instrument. The module provides a log-linear analog
output, RS485 serial communications, and one setpoint relay. In addition, a built-in display provides a
convenient user interface for setup and operation of the vacuum gauge. The measurement range for the
IGM401 hot cathode ionization gauge is 1 x 10
1.2
Specifications
measurement range
accuracy - N
(typical)
2
repeatability - (typical)
display
materials exposed to gases
sensitivity
x-ray limit
emission current
degas
overpressure protection
internal gauge volume
temperature
bakeout temperature
humidity
weight
housing (electronics)
mounting orientation
altitude
serial communications
analog output
setpoint relay
status outputs
input signal
filament selection
input power
connectors
CE compliance
environmental
InstruTech, Inc.
-9
to 5 x 10
-9
-2
1 x 10
to 5 x 10
Torr / 1.3 x 10
-8
-2
1 x 10
to 5 x 10
Torr; ± 15% of reading
± 5% of reading
OLED graphical display, 3 digits plus 2 digits exponent, user-selectable Torr, mbar, or Pa
dual filaments: yttria coated iridium or optional tungsten
Ion collector: tungsten
Grid: tantalum
factory pre-set. Also user adjustable between 2 to 99 using the display
-10
-10
< 5 x 10
Torr, < 6.7 x 10
mbar, < 6.7 x 10
100 µA, 4 mA, or automatic switching between 100 µA and 4 mA
3 W, electron bombardment
gauge turns off at factory default setting of 5 x 10
3
3
1.0 in
(16.4 cm
)
o
operating; 0 to + 40
C
storage; -40 to + 70
o
200
C (sensor only - electronics removed)
0 to 95% Relative Humidity, non-condensing
0.6 lb. (0.27 kg) with NW25 KF flange
aluminum extrusion
any
operating; 8,200 ft. (2,500 m) max
RS485 - ASCII protocol; minimum command interval: 50 ms
log-linear 0 to 9 Vdc, 1 V/decade
one single-pole, double-throw (SPDT), 1A at 30 Vdc resistive, or ac non-inductive
degas & filament on/off status are determined by display messages,
via open collector transistor or RS485 communication
degas and filament on/off & emission current are set by continuity to ground
using digital inputs, RS485 or manually using front panel push buttons
filament 1 or 2 selectable via front panel push buttons or RS485 commands
20 to 28 Vdc, 30 W protected against power reversal and transient over-voltages
9-pin D-sub male for analog and 9-pin D-sub female for RS485
EMC Directive 2004/108/EC, EN61326-1, EN55011
Low Voltage Directive 2006/95/EC, EN61010-1
RoHS compliant
-2
Torr.
-9
-2
to 6.7 x 10
mbar / 1.3 x 10
Others: 316/304 SS, glass, nickel
-8
Pa
-2
Torr
o
C
storage; 41,000 ft. (12,500 m) max
IGM401 Hornet
-7
to 6.7 Pa
Page 4
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Troubleshooting
