BK Precision 1403A User Manual

EIRCIITT
DESCRIPNON
v
BLOCK DIAGBAM
ANALYSXS
Refer
to Fig.
2, whieh is a
bloek diagram
of
the
oseilloseope.
The
vertieal ehannel
eireuits
inelude
the
vertieal attenuator
and vertieal
amplifier.
The
VERT INPUT
signal
is
applied
through
the
AC-DC
switeh,
whieh seleets
eapaeitive
or
direet
eoupling,
Md through
the V ATT
(verti-
eal attenuator)
to the vertieal
amplifier.
The
vertieal amplifier
is
a
highly stable,
direet-
eoupled
differential
amplifier with
a
gain
of
approximately
61
dB,
giving
a maximum
sensi-
tivity of approximately
10 mV
per
division.
The
vertieal attenuator and
vertieal
gain
eon-
trol
reduee the signal when
less output
is
re-
quired.
The
output of
the vertieal amplifier
is
applied
to the
vertieal defleetion
plates
of the
CRT when
the NOR-DIR
switeh is
set to NOR.
When
the
NOR-DIR
switeh is set
to
DIR,
the
output of
the vertieal amplifier
is
diseonneet-
ed and
a signal
from the V DIR and
GND
ter-
minals is applied
direetly to the
vertieal
de-
fleetion
plates.
The
horizontal ehannel eireuits
inelude
a
sweep
generator
for
a time
base and
a
hori-
zontal
amplifier. The
reeurrent type
sweep
generator
is a
free
running sawtooth
oseillator
whieh
produees
the sweep waveform.
Its fre-
queney
range
is seleeted
by the SWEEP
RANGE switeh, and
fine frequeney eontrol
is
provided
by the SWEEP VAR
eontrol
The
INT-EXT switeh seleets
the syne signal
for
the
sweep
generator from
the
vertieal ehannel,
or
the
EXT SYNC
input.
The sawtooth
wave
is
amplified
by
the
horizontal amplifier and applied
to the
hori-
zontal
defleetion
plates
of the CRT.
The
horizontal
amplifier
is
a
stable,
direet eoupled
differential
amplifier
with a
gain
of approxi-
mately 35
dB. The
horizontal
amplifier
may
also be used to amplify
an external
signal
applied at
the HOR INPUT
jaek.
In this
mode,
the
EXT GAIN eontrol
allows
the
gain.
to
be
varied
by about
10 dB.
The
power
supply
provides
operating
volt-
ages
for
all eireuits.
The
regulated
+15
V'
-15
V,
and
-6
V sourees
are used
in the
vertieal
preamplifier
and sweep
generator eireuits.
thg
+170
V souree
is used
in the
vertieal
and
horizontal
final amplifier
stages.
The
high
voltage souree
provides
about
-1400
volts
aeeeleration
voltage
for
the CRT
beam.
The
Z-axis
input
is applied
to
the
eontrol
grid'
where
it
may be
used as
intensity
modulation
of
the CRT
beam.
YEBIICAL
CHANNEL
CIRCI'NS
Refer
to Fig.
3
for a
simplified
diagram
of
the
vertieal
ehannel
eireuits
and
to the
sehe-
matie
diagram
in
the
rear
of the
manual
for
full eireuit
detaills.
Input Cireuit
;
The
vertieal
input
signal
is
first
routed
to
the
AC-DC
eoupling
switeh,
53.
Switeh
S3
seleets
or
bypasses eapaeitor
Cl.
In the AC
position,
Cl
is eonneeted
in series
with
the
input. In
the
DC eoupling
position,
eapaeitor
Cl
is
bypassed
and
the
input
signal
is eoupled
direetly
to the attenuator
switeh.
Vertieal
Attenuator
The
basie sensitivity
of the
vertieal
ehannel
is
10
mV/division.
The
vertieal
attenuator
expands
the
input
range
by offering
three
sensitivity
steps of
10
mV/div, 0.1
V/div'
and
1
V/div.
This is aehieved
by
voltage
divider
networks,
seleeted
by S1a and
Slb'
whieh
attenuate
the input
to
the vertieal
preampli-
fier
by
Xl
(direet),
X10,
or
X100. Trimmer
eapaeitors
TC101
and
TC102
provide
frequen-
ey eompensation
for the
XL() and
X100
steps'
to
mateh
the
Xl step.
A
eonstant
input
impe-
danee
of 1
Megohm
is
maintained
in all
steps.
A
fourth
step
of
switeh
S1
opens the
VERT
IN PUT
path
and
grounds the
input
of
the
vertieal
preamplifier.
This establishes
a
v
eonvenient
0-volt
referenee.

BK Precision 1403A Specifications

General

Brand	BK Precision
Model	1403A
Category	Test Equipment
Language	English