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CHANNEL AMPLIFIER
EBI-36)41
Control
Adjustment
SYNC HGT
If one
or
two composite outputs are desired,
connect the jumpers
as
shown in the Elementary
Diagram,
Fig. 15.
Adjust the sync amplitude
as
desired.
The amplitude
is
nominally
set
at
0.)4
volt with 1.0 volt peak
-to -peak
video
output.
CABLE
COMP
Set to closest length
of
camera cable used.
Do
not use for cable lengths under 200 feet.
APER CORR
GAMMA ON-OFF
Set to the amount of
high -frequency boost desired.
The signal-to-noise ratio
of the
video signal
may determine
the amount
of
boost that can be
tolerated.
If no
boost
is
desired, set the
control
to OJF.
This
control
is
normally used with Vidicon
cameras.
If
black stretch
is
desired, set to
ON.
For
no
gamma correction,
set to OFF.
Gamma correction
is
automatically removed when using negative
video.
THEORY AND CIRCUIT ANALYSIS
Refer
to the
Block Diagram,
Fig.
1)4,
and the
Elementary
Diagram, Fig.
15.
The Channel Amplifier
is
designed
to
amplify and mix shading
and
blanking
signals with the camera video signal
to
provide output signals suitable for
transmission and monitoring.
APERTURE CORRECTION
The
generated video signal from the television camera
is
fed
to the
Amplifier through
Jl,
and
to
the shunt
peaked video amplifier,
Vl.
APER
CORRection switch
Si
is
used
to
select
a
capacitive value
to
be
in
parallel
with cathode resistor
R7,
which will result
in a
rising frequency response
to 10
megacycles.
This rising frequency response compensates for the loss
of
resolution due
to the
finite spot size
of
the camera tube beam.
The
amplified video signal
is
coupled
to
the gain control amplifier,
V2,
through capacitor
C3.
BALANCE control R11
is
adjusted
to
provide
a
minimum distortion by equalizing the current in both sections
of
the gain
control stage,
V2.
VIDEO REVERSAL
Phase splitter
V3A,
which
is
part
of the
aperture correction
circuit,
provides phase correction and video reversal
of
the video signal.
The
7
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