MIL-PRF-1/1698D
TABLE I. Testing and inspection - Continued.
1/
Each tube shall have an individual serial number permanently marked on the cathode.
2/
In determining tube response (count rate) Ebb = 700 V dc and Rp = 1 MegΩ ± 10%. Tube count rates shall be determined using a
scaler having a resolving time of 5 µs and a discrimination level of 0.25 volts.
3/
The tube shall be exposed to radiation from a General Electric 15-watt germicidal lamp and a General Electric 15-watt
fluorescent lamp, or equivalents, with relative positions as shown on figure 2.
4/
Test shall be performed at the conclusion of the holding period.
5/
Method B (MIL-STD-1311, test method 6216); the scaler of 2/ may be utilized for this test.
6/
The response characteristics, current, and count rate versus field intensity of a type 7301 radiation counter tube shall be
as shown on figure 3. In determining tube response, Ebb = 700 V dc and Rp = 1 MegΩ ± 10%. Tube current shown as measured
by means of a microammeter in series with the tube cathode, and the count rates as determined using a scaler having a
resolving time of 5 µs and a discrimination level of 0.25 volts.
7/
Use Government approved standard gamma test unit.
8/
Criterion for passing this test shall be compliance after test of at least 80 percent of the tubes with the requirements for:
a.
Starting voltage.
b.
Gamma response (count rate).
c.
Pulse amplitude (1) and (2).
d.
End-of-plateau voltage.
e.
Relative plateau slope.
9/
The tube shall be rigidly mounted in positions X, Y, and Z, by means of a clamp at the center of the cathode. The tube shall
be given 10 blows at the X position and 5 at each of the other test positions.
10/
The limits for acceptability shall be as follows:
Background, contamination, and photosensitivity:
12 Npm, maximum.
Starting voltage:
Initial value ± 10 volts.
Plateau length:
125 volts, minimum.
Relative plateau slope:
0.25 percent/V dc, maximum.
End-of-plateau voltage:
750 volts, minimum.
Gamma response (count rate):
Initial value ± 10 percent.
Pulse amplitude (1) and (2):
Initial limits.
11/
The tube shall be mounted with its longitudinal axis horizontal and perpendicular to the direction of motion by means of a
rigid clamp at the center of the cathode. The time for gradually covering the frequency range shall be 15 minutes.
12/
W ith the tube in a field giving 100 ± 10 Nps at 700 V dc, the tube response (count rate) at 675, 700, and 725 V dc shall be
determined at each of the following temperatures and in the order shown:
1.
Room temperature.
2.
-40°C.
3.
Room temperature.
4.
+75°C.
5.
Room temperature.
A minimum stabilization of 30 minutes shall be allowed at each temperature. The absolute count rate at 700 V dc, and the
average relative plateau slope as determined by the readings at the 3 voltages (best average position of straight line), shall
not differ from the initial readings at room temperature by more than 10 percent and ± 0.1 percent/volt, respectively, at any
of the four subsequent temperatures shown.
3
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