Each electron gun is electrostatically focused by a
common grid voltage. In other words, each gun has
its own electrode, but all three are connected together
requiring only one grid voltage. The three electron
beams scan the screen and are controlled by the
deflection yoke mounted externally around the neck
of the tube. As the three beams scan the phosphor
screen horizontally and vertically in the standard
scanning pattern, the dot triads light up according to
the video input signals (fig. 5-34).
The purifying coil produces a magnetic field
within the tube that aligns the electron beams parallel
to the neck of the tube. Rotating the purifying coil
adjusts the electron beams so they strike their
respective color dots without striking neighboring
dots. When this adjustment is made for the red dots,
the other two electron beams are aligned as well.
The high-voltage anode is a metallic ring around
the tube. The field neutralizing coil aids color purity
at the outer edges of the picture tube. A metal shield,
called a mu-metal shield, is placed around the bell of
the tube to prevent stray magnetic fields from
affecting the electron beams.
Q1.
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Q12.
REVIEW QUESTIONS
Which heading indicator displays the most
information?
Are the three control boxes in the HSI group
interchangeable between the stations?
On the BDHI, what is the lubber index?
What does HUD stand for?
What does TDS stand for?
What is a combiner, as used with the HUD
system?
How many different dc voltages are used in
the HUD unit?
In the HUD system how many basic modes of
operation are there?
The SENSO ARU receives inputs from what
source?
What is another term for a camera tube?
What process is referred to as scanning?
How many elements are contained in a
standard television signal?
5-27
