MIL-PRF-1-590 Electron Tube, Cathode Ray Type 3Fp7A

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MIL-PRF-1/590C

TABLE I. Testing and inspection - Continued.

NOTES:

1/ This test to be performed at the conclusion of the holding period.

2/ The deflecting plates shall be returned to anode number 2 through a minimum of 2.5 megohm resistors. lb3 the

beam current shall be set at 150 A dc. The high-frequency scanning shall be applied to the deflecting plates

nearest the screen and the amplitude shall be adjusted to give a line length of approximately 90 percent of the

maximum tube diameter. The low-frequency scanning amplitude shall be expanded to approximately 90 percent

of the maximum tube diameter in the direction perpendicular to the direction of high-frequency scanning.

Readjustment may be made for best overall focus.

a. The tubes shall be observed for deflection defocusing, astigmatism or spot ellipticity observable to the eye as

evidenced by fuzziness due to lack of sharpness of trace (usually around edges) bow-tying (irregular widths of

any single line when observed at different points) bowing of trace other than that normally caused by curvature

of bulb.

b. This test for focus is to be made in addition to the line width measurements.

3/ The same conditions shall be set up as described in 2/ except that the connection of deflecting elements to the

low- and high-frequency scanning supplies shall be interchanged and the amplitudes adjusted to 90 percent of the

maximum tube diameter in both directions without any adjustment of focus from note 2 conditions. An

examination for defocusing, astigmatism or spot ellipticity shall be made as in note 2.