Tektronix 465M User Manual

start voltage
which is
set
by
R2782).
The
output of the
Miller
op
amp
sets pin
2 of
U2790
to the sweep
start volt-
age
also.
2 At Triggering.
Pin
13 is always
LO, except in
the X-Y
mode. When
pin 13 is HI,
point
A (see
Figure 4-6)
is HI
regardless of the
state of pin
14. When
the sweep gate
causes pin 14
to
go LO, point
A steps
LO (see
Figure 4-6).
This causes
the output
of the sweep
start comparator
to
become
a high-impedance
point.
The
timing
capacitor
(Ct)
starts charging
through
the timing
resistor
(Rt).
3 During Ramp
Generation.
As
Ct
starts charg-
ing
through
Rt,
the inverting
input
of the
Miller
op
amp
tries
to go more
positive.
This
causes
the output of the
Miller
op amp
to
go
less
positive
which
supplies
current
through
Ct
and
Rt
to hold the
voltage
on the inverting
in-
put constant.
Since the
resulting
voltage
across
Rt
is con-
stant, the
current
through
Rt
and
Ct
must
also be constant.
Charging
Ct
with this
constant
current
produces
a
linear
negative-going
voltage
ramp
at pin
2 of
U2790.
The slope
of the ramp
is
determined
by the
values
of
Rt
and
Ct
which
are selected
by the
A TIME/DIV
switch
(S3100).
The ramp
at pin
2 is
internally
connected
to pin
5 of
U2790
whenever
pin 7 is
LO. Pin
7 is
HI in
the
MIXED
and
B
DLY'D
positions of
the
HORIZ
DISPLAY
switch and
LO
in
the
A and
A
INTEN
positions
of the HORIZ
DIS-
PLAY
switch
and in
the X-Y
mode.
AIR FORCE T033A1-13-496-1
NAVELEX
0969-LP-170-0010
Operation
Instructions
4 At Delayed
Gate
Generaton.
The
negative-
going ramp
at pin 2 of
U2790 is internally
connected
to a
comparator. The
ramp is
compared
to the
dc voltage
on pin
1 of
U2790 (set
by the DELAY
TIME
POS
control).
When
the ramp voltage
is the same
as the voltage
on pin
1,
the
comparator triggers
the delayed
gate multivibrator
sup-
plying
a negative-going
gate
pulse
to
pin
16 of
U2790.
This
gate
is connected
to the B
holdoff
comparator
(Q2672 and
Q2674) and terminates
B
holdoff.
The
negative-going
gate
from pin
16 of
U2790 is also
connected
to the
base of
Q2622
through
CR2608,
CR2617,
CR2618,
and
CR2622.
This
allows
the B
sweep gate,
from
the
B trigger
ampli-
fier
(Q2602
and
Q2604), to start
B sweep
generation.
Both
signals
must
be
LO at the
same time
to start
B sweep.
5 Sweep End.
The ramp
on pin
2
of
U2790 is
internally
connected
to
the sweep
stop comparator.
When
the ramp
reaches
—2.4
volts, the
comparator
switches
sup-
plying
a positive-going pulse
to
pin
10 of
U2790. This
pulse is supplied
to the Sweep Control
circuit
and initiates
A
holdoff. At the
beginning of holdoff,
the sweep
gate
causes pin 14 of
U2790 to step HI
causing pin
4 to again
appear as
a
low-impedance
point.
The current through
Rt
is now supplied
by
pin
4 of
U2790. Also, when
pin 14
of
U2790 steps
HI, it causes
pin 12
to
step HI
and
initiate
B holdoff.
A
SWEEP
GATE
PIN
14 OF
U2260
A SWEEP GATE
PIN
14 OF
U2790
A
SWEEP
RAMP
PIN
2 OF
U2790
DELAY
TIME POS
SET TO
ABOUT
5.00
B DLY'D GATE
PIN
16 OF
U2790
CRT UNBLANKING
PIN
12
OF
U2790
HOLDOFF
START
PIN 10 OF
U2790
Figure
4-7.
Waveforms
produced
during
A sweep
operation.
4-15

Tektronix 465M Specifications

General

Brand	Tektronix
Model	465M
Category	Test Equipment
Language	English