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The
voltage
gain
of
the
output
EF
is approximately
.995.
Since
this
figure
is
so
near
unity,
we
did
include
it
in our
gain
cal-
culations.
In the ADD
mode
R353,
R363
(2 K's)
and
R352
(5K)
bleed
off excess
current
to
maintain
a
quiescent
current
of
7.5
ma,
per
tube.
In
all
modes
other
than ADD,
R351
(6.5K)
provides
a constant
load
to
the
+100v
supply.
The
actual
value
of
the
+100v
supply
in
the
plug-in
is
usually
about
95v
(decoupled).
If
R351
was
not
placed
in
the
circuit,
the
change
in current
through
the
decoupling
resistors
in
the
main
frame
would
cause
the
voltage
to
rise
to
about
+97v.
V364
shifts
the DC
level
in the hybrid
cascode
circuit
about
55v.
The
base
of
Q373
and
the
base
of
Q383
are
tied
to pins
|
and
6,
respectively
of V364.
The plate voltage
of each
half
of the
tube
is
about
+68.2v,
which
puts
the
emitters
of
Q373
and
0383
at
+67.5v.
R359
is
adjustable
so
the
emitters
can
be
set
to
_exactly
+67.5v,
which
will
insure
the
plug-in's
compatibility
with
all
other
Tek
scopes
that
accept
lettered
series
plug-ins.
T301
and
7310
are
used
to prevent
oscillations
in
the ADD
mode.
They
act
as
parasitic
suppressors
by
providing
common
mode
signal
decoupling.
The
output
EF
provides
an
output
impedance
of
about
602
to
drive
the
main
frame
vertical.
R375
and
R385
(512
each)
in series
with
the
internal
emitter
resistance
of Q373
and
Q383,
about
92
each,
compose
the
602
output
impedance.
Current
is set
by the
longtail
circuit,
R373
and
R383
(9.1K)
to +12v.
The
high
frequency
adjustments
are
connected
across
pins
1 and
3
of
the interconnecting
plug.
One RC network,
R379
(5002)
and C379
(3-12
pf),
is adjusted
for a 7 nanosec
time
constant.
The other
RC network,
R377
(10KO and
C377
(5-25
pf), is adjusted
for a 100
nanosec
time
constant.
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