Tektronix SC 502, Инструкция по эксплуатации

Страница: 37 / 127

input channel that is connected to the output amplifier at
the end of each
sweep.
Trigger Amplifier
Trigger
amplifier
0340
and 0345 amplifies
the output
signal from the vertical preamplifier and
supplies it to
the
Theory
of Operatlon-SC
502
appropriate
connections of the
trigger pickoff circuit
to be
used as a
triggering signal source
for that
vertical channel.
The channell trigger amplifier also supplies the
signal
to
an
a
u
x
i
l
i a
r
y trigger
amplifier.
DIAGRAM
�
CIRCUIT DESCRIPTION
Vertical Amplifier & Trigger View
Delay Une
Delay
Line DL400 provides
approximately
140
ns
delay
for
the
vertical
signal.
which
allows
the
sweep
generator
circuits
time
to
i
n
i
ti a
t
e
a
sweep
before the
vertical
signal
reaches the vertical
deflection plates
of the crt. This lets
the instrument display the leading
edge
of
the
signal
that
originated
the
trigger pulse
when
using i
n
t
e
r
n
a
l
trigger­
ing.
Output Amplifier
0455
and
0450
are
connected
as
a
common-base
amplifier to provide
a
low i
n
p
u
t impedance
to
properly
terminate
the
delay line. It also provides isolation between
the delay line and the following stages.
0465
and 0460 com pose
an emitter-coupled push-pull
amplifier that drives the
output
power amplifiers 0475 and
REV B APR 1980
0470. R461,
R460
and
R470 s
e
t the gain of the
stage by
controlling the signal degeneration between the emitters
of
0465
and
0460. yariable
capacitor
C474
and the series
rc networks provide high-frequency compensation
to
optimize
amplifier frequency response.
L470 and L475 are
high-frequency
p
e a
k
i ng coils to
p
r
o
v
i
d
e
additional
amplifier speed.
Trigger
View
Trigger view amplifier
0440 and 0435
amplify the
output
signal
from
the trigger comparator
and supply
it to
the TRIGGER VIEW switch. When
the TRIGGER VIEW
switch is depressed, the vertical signal from each vertical
channel is summed and split
equally by
R427-R425 and
applied to each
side
of the
delay
Ii ne. At the same time the
triggering
signal i s applied
differentially
to each side of the
delay line. The
trigger
signal is now a m
p l i f
i
e
d and
displayed as
the
vertical signal.
3·3