A
Sweep
Holdoff
Amplifier
0854
is
the
A Sweep Holdoff Amplifier. The holdoff
gate waveform
is
applied
to
the
base
of
0854
through R858
and C858 from pin 17 of U870. When
0854
is
turned
off
(during holdoff
time),
its collector
is
LO
and CR851
is
forward biased, which resets
both
the
Arm
and
Fire trigger
TD's
in
the
A Trigger
Generator.
When
0854
is
turned
on
(any time
other
than
holdoff
time),
its collector level
is
HI
and CR851
is
reversed biased. This allows
the
trigger TD's
in
the
A Trigger Generator
to
respond
to
the
next
adequate
triggering signal.
B Sweep Holdoff Amplifier
0804
is
the
B Sweep Holdoff Amplifier. Its circuit
action
is
identical
to
that
described for
the
A Sweep
Holdoff Amplifier
except
that
there
are three gate signal
sources
that
control
the
state
of
the
stage.
The
three
sources are
the
holdoff
gate from pin 17
of
U870 (through
CR859),
the
collector
of
01052
in
the
Delay Pickoff
Comparator, and
the
collector
of
0822
in
the
B Latch
Multivibrator (through
CR809).
All
three gate sources must
be
in
their
LO
state
for B Sweep
to
be triggerable; any one
of
the sources
in
its
HI
state
will disable
the
B Trigger
Generator TD's.
A Sweep Z-Axis Gate
01304
and
01306
comprise
the
A Sweep Z-Axis Gate.
They form an
emitter-coupled
stage where
only
one
transistor can be conducting
at
any
time.
The controlling
signal inputs
come
from
the
collector
of
0862
in the A
Sweep Gate,
the
blanking signal from
01014
in
the
A
Sweep Generator,
and
0824
in
the
B Latch Multivibrator
(only
in
the
MIX
mode
of
operation).
The
blanking signal
for use
in
the
Z-Axis Amplifier
is
taken
from
the
collector
of
01306
(through
CR1342).
The
collector signal
of
01304
is
applied
to
the
+A GATE
Emitter
Follower.
In
all
positions
of
the
HOR IZ DISPLAY switch
except
for B DLY'D,
-8
volts
is
connected
to
the
cathode
of
CR1341. This pulls
the
anode
of
CR1306
down
very close
to
-8
volts, causing
CR1306
to
be reverse biased, which
in
turn
allows
the
gate signal
at
the
collector
of
01306
to
pass
through
CR1342.
In
the
B DLY'D position
of
the
HORIZ
DISPLAY switch,
-8
volts
is
no longer
connected
to
CR
1341.
This allows
CR
1306
to
be forward biased, which
pulls up on
the
cathode
of
CR
1342.
This reverse-biases
CR1342, which blocks
the
A blanking signal from reaching
the
Z-Axis Amplifier.
In
all positions
of
the
HORIZ
DISPLAY switch
except
MIX,
-8
volts
is
connected
to
the
cathode
of
CR832.
This
keeps CR831 reverse biased
and
prevents
the
collector
signal
of
0824
from affecting
the
A Z-Axis Gate. However,
®
Circuit
Description-465
in
the
MIX
pos1t1on
of
the HORIZ DISPLAY switch,
-8
volts
is
no longer
connected
to
CR832.
Now, when
the
B
Sweep ends and sets
the
B Sweep Latch circuit,
the
collector signal
of
0824
(through
CR831)
switches
the
A
Sweep Z-Axis Gate causing
the
CRT display
to
be
com-
pletely blanked. This prevents any
further
display of A
Sweep
in
the
MIX
mode
even
though
A Sweep may still be
running.
B Sweep Z-Axis Gate
01324
and
01326
compose
the
B Sweep Z-Axis Gate.
They form
an
emitter-coupled stage where normally one
transistor
is
on and
the
other
is
off. The controlling signal
inputs come from
the
collector
of
0812
in
the
B Sweep
Gate and
the
blanking signal from
01074
in
the
B Sweep
Generator. The blanking signal
for
use in
the
Z-Axis
Amplifier
is
taken from
the
collector
of
01326
(through
CR1344).
The collector signal
of
01324
is
applied
to
the
+B
GATE Emitter Follower.
In
the
A position of
the
HORIZ DISPLAY switch,
-8
volts
is
applied
to
the
cathode
of
CR1347,
which causes
CR1345
to
be back biased.
The
collector
of
01326
is
pulled positive through R1326 and
CR1326,
which
in
turn
back biases
CR1344,
preventing
the
B Sweep Z-Axis Gate
from affecting
CRT
unblanking.
In
the
MIX
and A INTEN
positions
of
the
HORIZ DISPLAY switch,
-8
volts
is
removed from
the
cathode
of
CR1347
and applied
to
the
cathode
of
CR
1327.
This forward biases
CR
1345
and
reverse biases
CR1326.
CR1344
is
still reverse biased,
but
when B Sweep starts,
the
collector
of
01326
steps negative
enough
to
forward bias
CR1344
and
add
a slight
amount
of
unblanking
to
the
A Sweep unblanking already present.
This provides a measure of intensification for
the
B Sweep
portion
of
an A INTEN
or
MIX
display.
In
the
B DLY'D
position
of
the
HORIZ DISPLAY switch,
-8
volts
is
applied
to
the
cathodes
of
CR1327
and
CR1347.
This
reverse biases
both
CR1345
and
CR1326,
which allows
the
full B Sweep unblanking signal
to
pass
through
CR1344.
Since
the
A Sweep Z-Axis Gate
output
diode
CR
1342
is
held reverse biased,
the
only unblanking signal present at
the
input
to
the
Z-Axis Amplifier will be
the
B Sweep
signal.
+A
GATE
And +B
GATE
Emitter Followers
01314
and
01334
are
emitter
followers providing
the
+A GATE
and
+B
GATE
output
signals available
at
the
instrument
rear panel. The
output
signals are positive-going
rectangular waveforms,
approximately
5.5
volts in ampli-
tude.
The
amplitude
is
set in
the
collectors
of
01304
and
01324.
For example, when
01304
is
conducting
the
base
of
01314
can go
no
more negative
than
approximately
-0.7
volt {limited by
CR1304).
When
01304
is
not
conducting,
the
base
of
01314
rises
to
the
decoupled +5
volts power supply level
through
R1304.
CR1315,
CR1316,
3-13
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