Operation; Description Of Controls; Function Switch; Zero Knob - Thermo Scientific RO-20 Operating Manual

2. Operation

2.1

Description of Controls

2.1.1

Function Switch

The function switch is a nine-position rotary switch that turns the instrument off, checks the
condition of the batteries, checks instrument zero, and selects the range of operation to be
used.
2.1.2

Zero Knob

The Zero Knob is used to set the meter to zero when the Zero position of the Function Switch
is selected or when the detector is not in a significant radiation field (< 30µR/h).
2.1.3

Light Switch

The Light Switch illuminates the meter. It has three positions: Off, Momentary and On.
2.1.4

Calibration Controls (Internal)

Five variable resistors, one for each range, provide internal calibration controls.
2.2

Using the Instrument

The higher radiation field strengths measurable by the RO-20 can cause personal injury in a
short time.
Before using the instrument check Battery 1 (AA cells) and Battery 2 (l2V alkaline cells). The
meter should indicate in the green Battery Check arc. Do not leave the Function Switch in the
Battery 2 position for an extended period.
Turn the Function Switch to the Zero position. Check that the meter reads "0." If not, set it to
'0' with the Zero Knob.
Set the Function switch to the desired range of operation. The switch position selected is the
full-scale reading of that range.
When measuring ß, low-energy γ or x-ray emissions, open the sliding ß shield on the bottom
of the case and face the bottom of the instrument toward the radiation source. To open or
close the shield, press the friction-release button on the left side of the case and manually
move the slide or let it fall due to gravity. When the shield is open, protect the thin face
against puncture damage.
Ro-20
Löw 08.10.2008
RB-XXX-XXXXXX E 2-1