Downloaded from https://www.everyspec.com MIL-STD-1311D METHOD 2202 X-RADIATION MEASUREMENT (Receiving - high voltage rectifiers and shunt regulators) 1. Purpose. To obtain the x-radiation intensity of high-voltage rectifier and shunt regulator tubes to determine the levels emitted by the tubes when operated at high voltages without external shielding. 2. Equipment. 2.1 Survey meter. A dose-rate meter (electrostatically shielded) for probing or rapid surveying of a radiation field (Victoreen Model 440 RF/C, or equivalent). This meter, with a chamber of 10 cm 2 cross-sectional area, is intended to be the principal measuring instrument. NOTE:
Other detectors of low-energy x-radiation may also be used; such as Geiger-Mueller counters, proportional counters, scintillation counters, or solid-state counters, provided that the calibration is known over the energy ranges being measured and differences in cross-sectional areas of the detectors are considered. 2.2 Test equipment. To provide stable electronic conditions for operation of the TUT and to measure anode voltage and current. NOTE: Test equipment shall be so designed as to shield operators to below acceptable personnel safety level. 2.2.1 High-voltage meter. A meter for measurement of the high voltage during test, with an accuracy of at least ± 0.5 percent.
Calibrate using a high-voltage divider with suitable accuracy and stability. 2.2.2 Current meter. A meter for measurement of the current during test, with an accuracy of at least ± 2.0 percent. 2.3 Survey-meter support. A holder for supporting the survey meter during exposure in the recommended positions. It shall be constructed of wood or plastic and shall not lie between the meter and the tube. 3. Calibration. 3.1 The survey meter shall be calibrated by exposure to an x-ray field of such an energy that half-value layer of aluminum is 1.1 mm. This results in an effective energy of about 23 kiloelectron volts (keV).
The calibrating dose rate shall be representative of the intensities to be measured. This calibration shall be made traceable to the National Institute of Standards and Technology. NOTE: To insure accurate instrumentation, consideration should be given to correction factors for extreme variations in temperature and barometric pressure. 3.2 Stability of the calibration may be checked periodically by using an appropriate radioactive source. 4. Test conditions. 4.1 The TUT shall be positioned relative to the test equipment so that measurements will be made at the point where maximum radiation is observed. 4.2 Shunt regulators.
The TUT shall be operated at the maximum rated high dc anode (not supply) voltage and current, which shall not vary or drift, including ripple, more than ± 0.5 percent during the entire test period. If the combination of maximum rated high dc anode voltage and current produces a dissipation value in excess of the tube type's maximum anode dissipation rating, the current shall be reduced by an amount such that the maximum rated anode dissipation value is acquired without reduction of the rated dc anode voltage. 4.3 High-voltage rectifiers. These tubes shall be tested under dc conditions.
A dc potential, corresponding to the maximum rated peak inverse voltage (total dc and peak), will be applied to the cathode or filament. This voltage shall not vary or drift, including ripple, more than ± 0.5 percent during the entire test period. It is not necessary to energize the heater or filament during this test. The power supply impedance should be a minimum of 3 megohms to prevent arcing which can influence the radiation reading. METHOD 2202 2202-1 28 March 1975