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Instruction Manual
1 Introduction / General Information
1.1 Description
A cold cathode ionization gauge measures vacuum pressure by first ionizing gas molecules inside the vacuum
gauge and then measuring the resulting ion current. A large potential between the sensor anode and cathode
will cause ionization to occur. The amount of ion current generated from the ionized gas is proportional to the
pressure in the vacuum system and is dependent on the type of gas used. As the pressure inside the vacuum
system drops, the measured ion current drops. Two ion current collector options are available. The low current
collector option is recommended for use in heavy gases such as argon to prevent self-sputtering while the high
current version is recommended for gases such as N
The InstruTech® CCM502 Hornet™ module provides the basic signal conditioning required to turn a cold cathode
vacuum gauge into a complete measuring instrument. The module provides a log-linear analog output for the
measured pressure and requires a digital input to activate the sensor. Additionally, the instrument provides a
sensor on/off status using an open collector transistor output as well as a status LED. The measurement range
for the CCM502 cold cathode ionization gauge is 7.6 x 10
1.2 Specifications
measurement range
accuracy - N2 (typical)
repeatability - (typical)
materials exposed to gases
internal gauge volume
admissible pressure
temperature
humidity (30 days a year)
7.6×10-8 ... 7.6 ×10-3 Torr
7.6×10-9 ... 7.6 ×10-3 Torr
bakeout temperature (at flange)
weight
housing (electronics)
use
mounting orientation
input signal
analog output
output impedance
load impedance
error signal
response time
p = 7.6 X 10-9 Torr
p > 7.6 X 10-7 Torr
sensor status output
sensor status indication on gauge
InstruTech
/air, etc.
2
-10
to 7.6 x 10
7.6 x 10-10 to 7.6 x 10-3 Torr / 1 x 10-9 to 1 x 10-2 mbar / 1 x 10-7 to 1 Pa
7.6 x 10-9 to 7.6 x 10-3 Torr: ± 30% of reading
7.6 x 10-9 to 7.6 x 10-3 Torr: ± 5% of reading
anode: molybdenum
others: Ni alloy, AI
1.391 in3 (22.8 cm3)
145 psi, 10 bar absolute (limited to inert gases < 50
operating: + 5 to + 55
o
C
0 to 95% relative humidity, non-condensing
0 to 70% relative humidity, non-condensing
150
o
C (sensor only - electronics removed)
0.61 lb. (0.28 kg) with NW25 KF flange
aluminum extrusion
indoor
any
sensor enable (anode voltage turned on) is set by continuity to ground
log-linear 0 to 8 Vdc, 1 V/decade
2 × 4.7 , short-circuit proof
≥10 k, short-circuit proof
analog output switches to ≥ 10 V
~1 sec
<100 msec
sensor on/off status is determined by open collector transistor (ground emitter) rated at 30 V
max. V
, 100 mA max. I
Transistor off = Sensor off, Transistor on = Sensor on
CE
C.
sensor ON/OFF status indication via LED
-3
Torr.
O
, stainless steel, glass
2
3
o
C)
storage: -40 to + 70
o
C
CCM502 Hornet
Page 3
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