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This
"sampie"
of the vertical signal is also
ac-coupled,
through
V1223A
and
C1228,
to a
front-panel
jack
labeled
VERT.
SIG,
OUT.
Delay Line
The output signal from the Vertical
Amplifier
is coupled
through
the balanced
Delay
Line to
the
vertical
deflection
plates
of the crt.
The
function
of
the
Delay
Line
is
to
retard
the
arrival
of the waveform at the deflection plates
until the crt has
been
unblanked
and the hori-
zontal
sweep started.
This delay, as mentioned
previously, insures that the very " front" of fast
vertical
signals
can
be observed.
The
line is
adjusted,
by means
of the variable
capacitors
connected across the line, for optimum transient
response.
The
entire
Delay
Line,
which
includes the
plate' line
in the Distributed
Amplifier,
is re-
verse-terminated
in
its
characteristic
impe-
dance,
The Termination
Network, shown
on the
Vertical Amplifier diagram, is designed to dis-
sipate
both
the dc and signal energy in the line
by presenting a constant resistance over the fre-
quency
range of the amplifier.
The terminating
resistors
R1O71 and R1073 are specially made,
wirewound,
noninductive, distributed resistors.
The
600
ohms
total
resistance
in
each
is
"tapered" | or distributed, in steps. The largest
segment
of
the
terminating
resistance
appears
nearest
the line; the smallest segment appears
at the opposite end.
Each step of the resistance
is then tuned, by means of the variable capaci-
tors, so that the network will present an opti-
mum. load to the line.
CALIBRATOR
The calibrator is asymmetrical multivibrator
with
V670A and V670B connected so it will turn
cathode
follower
V246A
on
and off as it oscil-
lates.
During the negative pulse at multivibrator
V670A, the grid of the cathode follower is driven
well below cutoff, so the cathode is at ground
voltage.
During the positive pulse at the multi-
vibrator the plate is cutoff and rests slightly be-
low
+100
volts,
The voitage of the plate during
cutoff is determined by the setting of R679, part
of
a
divider
between
+100
volts
and
ground.
R679
is a screwdriver adjustment labeled CAL
ADJ.
Cathodes of the multivibrator are returned
to
-150
volts.
The
multivibrator
frequency
is
about one kilocycle.
Cathode
follower
V246A
has
a tapped
cali-
brated
voltage
divider for its cathode
resistor.
When the CAL
ADJ, control is properly set, the
cathode
follower
cathode
is at + 100 volts when
V670A
is cut off.
Taps on the divider divide the
100 volts down
to 50, 20,10,5, 2,1, .5, and .2
volts.
A second divider with a division ratio of
1000 to 1, can be switched inif desired to divide
these
voltages
into
millivolts.
C682
from
the
cathode-to-ground
corrects
a slight overshoot.
No
internal
connection
from
the
calibrator
to
the
vertical-deflection
circuits
is
provided.
Trigger
Amplifier
The trigger amplifier, V8, is agrounded-grid
cathode-coupled
linear amplifier.
A capacitor,
C3,
can
be
switched
into
the grid circuit to
remove
the dc component of the trigger signal.
Output
is always
taken from
the A-section plate,
but
the
TRIGGER
SLOPE
selector
connects
either
the
A-section
grid or the B-section
grid
to the
input
signal
source.
For positive-going
signals
connection
is made
tothe A-section grid,
and
for
negative-going
signals
connection
is
s
531/541—-Cl RCUIT
DESCRIPTION
made
to the
B-section
grid, and
in each
case
the opposite
grid
is connected to an adjustable
dc
bias
source,
adjustable
by
means
of
the
TRIGGERING
LEVEL
control.
R14 adjusts the
bias
on one half or the other of V8 to adjust the
de
level of the
A-section
plate
output.
The dc
level
of
the
plate
output
is important
to the
circuit
operation
in three
of the five positions
of the TRIGGERING
MODE
switch
because
in
these
three
switch
positions
the
input grid to
the trigger
shaper
stage,
V20A,
is dc-coupled
to the plates
of V8.
The
effect
of the dc level
is shown ina later paragraph.
Triggering Mode Switch
PAGE
3-7
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