Cpm Calibration - LUDLUM MODEL 3 Technical Manual

Model 3
Ludlum Measurements, Inc.
Technical Manual

CPM Calibration

Connect the input of the instrument to a negative pulse generator, such
as a Ludlum Model 500 Pulser.
Caution!
The instrument input operates at a high potential.
Connect the pulse generator through a 0.01 µF, 3000-volt
capacitor, unless the pulse generator is already protected.
Adjust the HV control for the proper operating voltage of the detector
to be used. Adjust the pulser negative pulse frequency to provide a
better meter deflection of approximately 80% of full scale on the ×100
range. Adjust the ×100 calibration control for the proper reading.
Check the 20% scale indication of the Model 3 by reducing the pulser
count rate by a factor of 4. The Model 3 should read within 10% of the
actual pulse rate. Decrease the pulse rate of the Model 500 by one
decade and turn the Model 3 range selector to the next lower range.
Repeat the above procedure for the remaining lower ranges.
Note:
In the event that any reading is not within 10% of the
true value on any scale after any of the above calibration
methods is performed, a reading within 20% of true
value shall be acceptable. It is acceptable if a calibration
graph or chart is provided with the instrument.
Instruments that cannot meet these criteria are defective
and require repair.
Page 6-3
Section 6
April 2016