Operation - Agilent Technologies FRG-700 User Manual

Technical Information

Operation

As soon as the required supply voltage is applied, the measuring signal is available
between pins 3 and 5.
Allow for a stabilizing time of approx. 10 min. Once the gauge has been switched
on, permanently leave it on irrespective of the pressure.
The gauge consists of two separate measuring systems: Pirani and cold cathode
system according to the inverted magnetron principle. They are combined in
such a way that for the user, they behave like one measuring system.
The optimum measuring configuration for the particular pressure range, in which
measurement is performed, is used.
The Pirani measuring circuit is always on

The cold cathode measuring circuit is controlled by the Pirani circuit and is

activated only at pressures <1×10
The identification output (pin 6) indicates the current status of the gauge:
Table 2
Pressure
p > 1x10
p < 1x10
p < 1x10
As long as the cold cathode measuring circuit has not ignited, the measuring value
of the Pirani is output as measuring signal.
Agilent Inverted Magnetron Pirani Gauge FRG-700 and FRG-702 User Manual
10
Cald cathode
5x10- 9 mbar
Lamp on the gauge
-2 mbar
-2 mbar
-2
mbar
-4 mbar
10- 2 mbar
-2
mbar
Operating mode
Pirani-only mode
Cold cathode not ignited
Pirani-only mode
Cold cathode ignited
Combined Pirani / cold
cathode mode
1000 mbar
Pirani
Pin 6
Low = 0 V
Low = 0 V
High = 15 ... 30 VDC
29