BK Precision 1403A User Manual

CIRCTITT
DESCRIPTION
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Fig.
2.
Bloek Diagram.
Vertieal
Preamplifier
The vertieal
preamplifier
is a
direet-
eoupled
differential
amplifier
made up of
three
stages,
an FET
input amplifier
Q101-
Q103,
a
buffer
stage
Q104-Q105,
and
a
tran-
sistor
amplifier
stage
Ql06-Ql09.
The first stage
is an
FET
input
amplifier,
Q101-Q103,
whieh
presents
a
very
high
input
impedanee. It
has negligible
shunting
effeet
on the
1
Megohm
input resistanee. The signal
side of
Q102
establishes
the
internal de
bal-
anee
for the entire vertieal amplifier
board.
VR101
(OC
BAL)
allows
adjustment
of de
balanee.
FET
Q101
provides
input voltage
overload
proteetion
and
FET
Q103
establishes
signal
ground
for
Q102
and
sueeeeding
ampli-
fier
stages.
Q102
and
Q103
are souree
eoupled
in
a differential amplifier eonfiguration;
the
input
signal applied
to
Q102
is eoupled
to the
souree of eommon
gate
FET
Q103.
rt
In
the seeond
stage
of
the vertieal
preamp-
lifier,
Q104
and
Q105
are emitter-followers
to
Q102
and
Q103.
These
transistors
aet
as
impedanee
eonverters,
eonverting
from
the
very
high
impedanee
of the
FETrs
to a
low
impedanee
drive
signal
for
the
transistor
amplifier.
Q106-Q109
form
the
third
stage
of
the
vertieal
preamplifier.
Vertieal
gain
(V
GAIN)
is
eontrolled
by front
panel
potentiometer
VRl
whieh
limits the
eurrent
fed
to
the bases
of
Q10S
and
Q109.
Stability
of
Q106-Q109
is
maintained
through
the
use
of
negative
feed-
baek
provided
by
C132
and
R178.
Signal
output
voltage
is
developed
aeross
resistors
RL22
and R123
from emitter
euments
of
Q108
and
Q109
and
fed
to the
final amplifier'
Q110
and
Ql11.
Ventieal
Final Amplifien
The
vertieal
final amplifier
stage
ineludes
differential
amplifier
Q110
and
Ql11..
A
high
frequeney
eompensation'network
may
be
trimmed
by adjustment
TC103
to aehieve
the
CRT
V.AMP
Ol01l,0111
H.
AMP
0114-Q116
SWEEP
NERAT
EXT
01
12.
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13
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BK Precision 1403A Specifications

General

Brand	BK Precision
Model	1403A
Category	Test Equipment
Language	English