Model 12-4 Technical Manual Section 6
Ludlum Measurements, Inc. Page 6-2 May 2016
A Ludlum Model 500 Pulser or equivalent is required. If the
pulser does not have an HV readout, use a high-impedance
voltmeter with at least 1000 Megohm meter input resistance to
adjust the detector voltage.
A neutron source capable of yielding dose-equivalent rates
ranging from 2 mrem/hr to 1 rem/hr in needed.
A
137
Cs source capable of yielding an exposure rate of 10 R/hr is
needed.
Initial Calibration Procedures
If any calibration procedure cannot be completed satisfactorily, the
instrument shall be tagged and removed for proper disposition.
Note:
When placing the Model 12-4 into its can, orient the
instrument so that the unimorph speaker is on the left side
when reading the meter dial. Noise can be fed into the preamp
of the instrument if it is placed backward into the can.
Ensure that the meter movement has proper mechanical zero. The
adjustment is on the front of the meter bezel. It must be adjusted to
"zero" with the Range Selector Switch in the OFF position.
Perform geotropism check.
Connect the Model 12-4 to the pulser or a certified high-impedance
voltmeter.
Rotate the range selector switch to the
BAT position. The meter pointer
should remain in the BAT TEST area of the meter dial.
Rotate the Model 12-4 Range Selector Switch to ×1000.
Adjust the
CAL HV potentiometer on the Model 12-4 for a reading of
1.5 kV on the pulser HV meter.
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