Tektronix 465M User Manual

AIR
FORCE T033A1-13-496-1
NAVELEX
0969-LP-170-0010
Operation
Instructions
(a) The +B
GATE
OUT Amplifier amplifies the
signal
from the +B
GATE
OUT
buffer. The output of this
circuit
is
connected to a rear panel mounted
BNC con-
nector. The output signal steps
to
about +5
volts during B
sweep ramp generation
and
about 0 volts the rest
of the
time. The circuit
consists of
inverting amplifier
0356,
emitter follower
0358,
and
associated circuitry.
(b)
When the input of
the circuitry
goes more
positive, 0356 turns on hard and
its collector goes
to about
+0.7
volts. This causes the emitter of
0358
to go to about
0
volts.
(c)
When the input
steps less
positive, 0356 turns
off and
the base of 0358 is pulled
more positive
through
R354.
The emitter of
0358 is prevented
from going more
positive than +5.1
volts
by
VR353.
(5)
Calibrator.
Figure
FO-8
shows
the Calibrator
circuitry. The Calibrator
generates
an accurate
1.0 volt
square wave
for use in probe
compensation and
checking
vertical
gain accuracy. The
circuit consists
of an astable
multivibrator and an
output amplifier.
(a) Multivibrator.
Transistors
0376
and 0382
form
an
astable multivibrator.
The
multivibrator
runs
at
approximately
1 kilohertz.
The frequency
is determined
by
the
RC time
constant of
C376-R377-R375.
Transistors
0376 and
0382 conduct
alternately,
producing
a
square
wave
output signal
at the collector
of
0382. Diodes CR372
and CR373
limit the charge
on
C376
to about 18 volts
to
prevent
damage
to 0376
or 0382
when either
transistor
is
removed
while
the instrument
is
operating.
(b) Output Amplifier. The square wave output
signal from the collector of 0382 drives the
output
ampli-
fier
(0386).
Transistor
0386 is alternately driven into
saturation, then into cutoff. This results
in a
0
to
+5
volt
square wave
at the collector of 0386. Amplitude
adjust-
ment
R386 sets the collector current in
0386 to produce a
1 volt square
wave across R388. This 1 volt square wave is
connected
to J387 on the instrument front panel.
(6)
Low
Voltage Power Supplies. Figure FO-10 shows
the
Low Voltage Power Supplies,
except for the
+95
volt
supply. Figure
FO-9 shows the +95
volt supply.
(a)
Primary
Circuit. All the supplies
except the
+95
volt supply receive
power from T700. To reduce
electromagnetic
interference, the
ac supply voltage is
filtered
by a
filter
which is part of P700.
There are two
windings
in the primary of
T700. These windings can be
placed in series
or parallel
by
the
line voltage selector
switch
(S701). The two windings
are placed in series for
operation from
a 232 volt power
source
or
in
parallel for
operation
from a 1
16
volt
power source.
(b)
+32
Volt
Supply. Figure
FO-10
shows
the
+32
volt supply.
The +32
volt supply
consists
of
U722A,
Q732,
Q734,
Q736 and
associated
circuitry.
1^
Operational
amplifier
U722A
controls
regu-
lation of the +32
volt
supply.
The noninverting
input of
U722A is set
to
+9
volts
by VR722.
The
output
of the +32
volt supply
sets the inverting
input
of
U722A
at
+9
volts
through
voltage divider
R735-R736-R737.
2 The
output
of
U722A
(about
+9
volts)
is
level
shifted
by a zener
diode
(VR725).
This level
shifted
voltage
controls
the
base drive
of Q732
and
Q736 which
are
connected
as a Darlington
amplifier.
Transistor
Q734
provides
overcurrent
protection.
3
Regulation
occurs
as follows.
Assume
the +32
volt
supply tries
to
go
less
positive.
This
is sensed
on
the
wiper of
R736 and
causes
the inverting
input
of
U722A
to
try
to
go
less
positive.
As
a result, the
output
of
U722A
goes
more
positive which
turns
on
Q732 and
Q736
harder.
When
Q736
turns on
harder,
the +32
volt
supply
goes
more
positive
which
corrects
for the
original
deviation.
(c)
+5
Volt
Supply. Figure
FO-10
shows the
+5
volt supply.
The +5
volt
supply
consists
of
U722B,
Q742,
Q744,
Q746
and
associated
circuitry.
2
The
reference
voltage for the
+5
volt supply
is obtained from the +32 volt supply
through R741 and
R742. The reference voltage sets the noninverting
input of
U722B
to
+5
volts.
2 The
inverting
input of U722B senses changes
in the
+5
volt supply through R743.
3 The output of
U722B
controls
conduction
in Q744 and Q746 which are connected
as a Darlington
amplifier. The conduction level
of Q746 controls
the
+5
volt supply
output
voltage. Transistor
Q742
provides over-
current protection
for the
+5
volt supply.
(d)
—5
Volt
Supply.
Figure
FO-10 shows the
—5
volt
supply. The
—5
volt supply consists
of U762,
Q764,
Q766,
Q768 and
associated circuitry.
In the
—5
volt supply,
the noninverting
input
of
the operational amplifier
(U762) is not referenced
to
the +32
volt supply
as
in
the
+5
volt
supply. Instead
it is
connected
to ground
(0
volts) through
R764.
2 The inverting
input
of U762 does
not di-
rectly
sense the
supply output voltage
as in the
+5
volt
supply. Instead
the inverting
input senses both
the +32
and
—5
volt
supplies through voltage
divider R763-R762.
This
sets the inverting
input
to 0
volts. Since
the +32 volt
supply
is constant, changes in
the
—5
volt supply
are
sensed
at
the inverting
input.
4-28

Tektronix 465M Specifications

General

Brand	Tektronix
Model	465M
Category	Test Equipment
Language	English