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EBI-3611
CHANNEL AMPLIFIER
H
CLAMPS, SHADING, AND
BUFFERED DRIVE
Horizontal pulses
are
fed
to the
Amplifier through
J7,
then applied
to
the grid
of
the pulse amplifier,
V11jA.
The pulses are inverted and
amplified for use
at
the clamp keyer, V13A.
Positive and negative
clamp
pulses
are
taken
off the cathode and
plate
of
V13A respectively, and fed
to
the
key clamping
diodes, CR1-CR2 and CRL-CR6.
Horizontal drive input pulses
are also
applied
to the
grid
of
the H
pulse buffer, V19A, through
C98 and R196.
The
positive output pulse
of
V19A
is
coupled
to the
horizontal sawtooth waveform for mixing with
the
vertical
saw
in V16.
The positive horizontal drive pulses are applied simultaneously
to the grid
of
V15 which turns the tube
on.
During
the time interval
between
the positive pulses, C66 in the plate circuit will charge towards the voltage
applied
to R97.
This
voltage
can be
adjusted between
+100 and -100 volts
at
the control console.
If the voltage
is
negative, the sawtooth will be
generated
in
a
negative direction; and
if
positive, the sawtooth will be
generated
in
a
positive direction.
During
the
horizontal pulse
time, ca-
pacitor
C66
will discharge through either V15A
or V15B.
The positive horizontal drive pulses from the output
of
V19A
are also
coupled
to clamp
keyer V13B which supplies negative and positive keying
pulses
to
blanking adjustments
R28,
BLANKING ADJ
POS,
and
R29,
BLANKING
ADJ
NEG.
The
positive horizontal
drive
pulses from V19A
are
coupled
to
V19B through C101 which inverts the pulses for buffered horizontal drive
to
the camera
jack,
J9.
V
BUFFERED
DRIVE AND SHADING
Vertical drive pulses applied
to J12 are
coupled through C95
to the
vertical pulse buffer,V18A,
and the
positive output
is
coupled
in
turn
to
V18B which inverts the pulse
to the
camera
jack, J10.
The vertical drive
input pulses are also coupled through
C78 to V1hR,
where
the
pulses
are
amplified and inverted
to
provide
a
positive input
to the
vertical saw
generator, V17.
Vertical saw generator
V17
operates in the same manner
as
V15,
with
the
positive
and
negative saw control connected
to the control
console through J17-11.
SHADING MIXER
Both
the
horizontal
and
vertical sawtooth generator outputs are fed
to the separate grids of
V16 and mixed by virtue
of the
common plate
of
the
sawtooth mixer with
the output coupled to the grid of
shading adder V12A
through
C64 and R93.
During the clamping pulse, the grid
of
V12A
is
clamped
to
ground, and
because
of
the large value
of
C6L
and R93, the vertical saw
-
tooth
is
not
affected except during the clamping pulse, resulting
in
a
waveform
as
shown in
Fig.
7.
Therefore,
it is
possible
to
mix
the shading
output from the cathode
of
V12A with
the video signal ahead
of
the video
clamp without clamping out the vertical sawtooth.
10
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