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I. I
Description
SECTION I
GENERAL INFORMATION
The
2
70 ionization gauge controller is a prec1s1on instrument designed to indicate
vacuum pressures from I Torr to 10-8 Torr, I mbar to 10-8 mbar, or 100 Pascal to 10 -6
Pascal, air equivalent. The basic unit is comprised of a power supply, electrometer, emission
controller, and ion gauge meter. Dual thermocouple gauge capability and process controls on
the ion gauge and thermocouple gauges are included on some models. Recorder outputs
provide capability for remote indication as well as continuous monitoring.
In the basic controller the
2
70 will display pressure data in five linear decades, 10-4 to
10 -8 Torr. The range of readable data is from 0.3 x IQ-8 to 1
2
x 10-4 Torr. The controller
is designed to utilize a Bayard-Alpert type transducer with sensitivity ranging from 10/Torr
to
2
5/Torr. The unit is shipped pre-adjusted for directly indicating pressure of a gauge having
a sensitivity of I 0/Torr, corresponding to an emission current of
2
mAdc.
Degas is provided by conventional resistive ( 1
2
R) heating of the grid surfaces with a
nominal 80 watts of power. Ion gauge pressure measurements are not possible during degas.
Ion gauge process controls, when included, provide two independent set points which
· operate individual SPOT relay contacts. Set point adjustment over the entire measurement
range is by means of recessed front pane I controls. Interlocks are provided to al low operation
only during auto range operation when the filament is on and the gauge has had sufficient time
to stabilize.
The thermocouple section is comprised of two independent measuring circuits and, when
included, extend the measurement range of the controller to I Torr or I mbar. Indication is
provided by two I ½1 inch taut band ruggedized meters. Recorder outputs are also provided for
each of the thermocouple circuits. The thermocouple circuitry is designed to operate with
Granville-Phillips
2
70006 or comparable transducers.
Thermocouple process controls, when included, provide an individual SPOT relay contact
set point for each thermocouple gauge.
Set point adjustment over the thermocouple's
measurement range is adjustable by means of recessed front panel controls. The controller is
wired such that the set point for thermocouple No.
2
can be used to switch the ion gauge
filament on and off, thus allowing fully automatic operation.
Alt Series
2
70 controllers come with an automatic ranging feature which can be
defeated placing the controller in a manual ranging mode. Autoranging points are preset to
occur at .95 x IO-x and 11.7 x IO-x • While in the manual mode the controller is capable of
readings from 0.0 x IO-x to 1
2
.0 x 10-x. Autoranging eliminates troublesome range changing
in a variable system and prevents unnecessary shutdowns due to momentary pressure bursts.
The manual/auto range function is selected via a front panel switch.
The
2
70 ion gauge controller provides direct ion gauge pressure readout in either Torr,
mbar or Pascal. The unit of measure is selectable by means of a jumper plug inside the
controller and appropriate front panel labeling.
The pressure signal is converted and
displayed in the desired format, thus eliminating cumbersome conversion tables or
calculations.
1-1
