GE 4PE350A3 Instructions Manual page 282

TUBE TYPES XQ1020L,M2102OR ,XQ1020G,X01020B
FOOTNOTES (continued)
16)
The figures shown represent,the typical horizontal amplitude responses of the tubes proper after correction
for faults introduced by the optical system.
Horizontal amplitude response can be raised by the application of suitable correction circuits. Such com-
pensation, however, does not affect vertical resolution, nor does it influence the limiting resolution.
17) Grid No. 3 voltage adjusted for optimum focuse. See also note 13.
18) The stated ratio represents the "visual equivalent signal-to-noise ratio," which is taken as the ratio of
highlight video -signal current to R. M. S. noise -current, multiplied by a factor of 3. (Assuming an
R. M. S. noise -current of the video pre -amplifier of 2. 10-9A, bandwidth 5 MHZ).
GENERAL RECOMMENDATIONS AND INSTRUCTIONS FOR USE
GENERAL
1.
Signal -electrode connection is made with a spring -contact against the metallic coating at the face
end of the tube, which is also part of the focusing coil.
2.
Electrostatic shielding of the signal -electrode is required in order to avoid interference effects
in the picture. Effective shielding is provided by grounding shields on the inside of the face -plate
end of the focusing coil and, on the inside of the deflecting yoke.
3. The Plumbicon is provided with tungsten base pins. Avoid mechanical force and shocks to these
pins and, insert the tube into its socket (type 56021) with care.
4.
In some cases the properties of the photo -conductive layer used in the Plumbicon may become
slightly deteriorated during long idle periods, such as encountered between the last factory test
and actual delivery to the user.
Operate the tube directly after receipt under normal voltage settings, in overscanned position
with evenly illuminated target and a signal current of 0.15 µA for several hours after which the
initial properties will have been fully restored.
5. The light -transfer characteristic of the Plumbicon is characterized by a gamma near unity, it
may be desirable for broadcast applications to incorporate a gamma correcting circuitry in the
video -amplifier system with an adjustable gamma of 0.5 to 1.
Design this gamma correcting circuitry so that an extra compression can be introduced by manual
control in the video signal range of 75 to 100% of normal peak white level.
This provision will prevent the video amplifier system from becoming over -loaded when the
Plumbicon with its near unity gamma transfer -characteristic is exposed to scenes containing small
peaked highlights as caused by reflections of shiny objects.
6. The Plumbicon does not generate its own noise to any noticeable extent, so the signal-to-noise
ratio will primarily be determined by the entrance noise of the video amplifier system.
The high sensitivity of the Plumbicon provides pictures with excellent signal-to-noise ratio under
normal studio lighting conditions provided its output is fed into a well -designed input stage of the
video -amplifier system. In such a system an aperture correction may be incorporated to ensure
an attractive gain in resolving power without visually impairing the signal-to-noise ratio.
Instructions for Use
1.
Insert the tube in the deflection unit so the mark at the base of the tube is on top.
2. Clean the face -plate of the tube and press the socket gently onto the base -pins.
3. Cap lens and close iris.
4.
Set: a)
Grid No.
1 bias -control at max. negative bias (beam cut-off).
b)
Signal -electrode voltage to the value as indicated on the tube's test sheet.
c)
Scanning amplitudes to max. scan.
5.
Switch on camera equipment and monitor.
6. Adjust monitor to produce a faint - non overscanned - raster.
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