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MODEL 2224-1 Technical Manual
Section 4
Ludlum Measurements, Inc. Page 4-3 January 2012
The ratio is selected from the following table. (O is open and C is closed)
SWITCH DIVIDE BY
1 2 RATIO
C C 1
O C 10
C O 100
O O 1000
Dipswitch 3 & 4 (SPARE)
:
Not used
Dipswitch 5 (TONE)
: a one-pole DIP switch used to select tone
discrimination between alpha and beta count channels. When in
DUAL
mode (
C
position), alpha and beta pulse tones will be audible in all
selector switch positions (i.e. if in the
α
only position and
β
is detected,
the β tones will be heard in addition to the α tones and visa versa).
When the
SNGL
tone position (
O
position) is selected, both alpha and beta
pulse tones can be heard in the α + β selection, but alpha pulses cannot be
heard in the beta only channel selection and beta pulse tones will not be
heard in the alpha only channel selection.
Dipswitch 6 (SPARE)
: Not used
The following controls are utilized during
calibration only and should only be adjusted by a
qualified calibrator.
MTR
: a multi-turn potentiometer used to calibrate the meter to the
CPM
reading.
AT
: a multi-turn potentiometer used to vary the alpha pulse threshold
from approximately -40 to -700 mV.
BW
: a multi-turn potentiometer used to vary the beta pulse upper
window limit from the beta threshold to the alpha threshold setting and
anywhere in between those two parameters. The beta window can be
disabled by adjusting the
BW
control to the maximum clockwise position,
allowing the upper beta threshold limit to equal the alpha threshold.
BT
: a multi-turn potentiometer used to vary the beta pulse threshold
from approximately -2 to -15 millivolts.