The etched
vernier segment
and
circumferential
0-107
hand
calibrating scale
provides
direct
reading to one
part in
1000
for
critical
laboratory usage
(see
page
19).
The
transparent
hair-line
indicator
affords
direct fre-
quency
readings,
free from
parallax.
6.
400 Cycle Sine-Wave
Oscillator
-
Independently
Controlled.
A
6U8 audio
frequency
oscillator
and cathode
follow-
er output
provides
the modulation
tone, as
well as
being
available
for external
text
applications.
The
unusually
high audio
voltage
output of almost
£0j£fl]£s
peak
(full-
ly
CjQfltTOlJ"^
0 frr«n
zero to maximum),
allows for the
DIRECT
testing
of audio
power-output
and
other cir-
cuits, absolutely
independent of all
other
stages. This
is of
primary
importance
in "SERVICING
BY SIGNAL
SUBSTITUTION"
as well
as
in routine
amplifier
trouble-
shooting.
Examination
of the
Series E-200-C
schematic
diagram
will
show
that the audio
oscillator
circuit is fully iso-
lated
from
external
circuits
and
voltages by
reason of
the cathode
follower
output stage.
7.
Dual R.F.
Attenuator
-
Low
Leakage.
Thorough
shielding;
electrostatically
shielded
power
transformer;
R.F.
-filtered
power
line
connections;
shielded
coaxial cable
connectors;
coaxial
output
cable;
in
addition to a
triple
shielded DUAL R.F.
AT-
TENUATION
NETWORK,
calibrated
for stage
by stage
R.F.
gain comparisons.
8.
Variable
Modulation
Control,
Direct Reading.
Another new
and
advantageous
feature of Series E-
200-C,
specifically
designed
for
"S-S-S",
is
the cali-
brated
Modulation
Control which
provides, At
Will
0-
100%
modulation
of the R.F.
signal.
This feature
originated in
previous models,
more than triples
signal
utility
and
audibility as
against Signal
Generators ap-
plying only
fixed
30% modulation. This
high level of
modulation,
free from
annoying
frequency
instability,
is
possible
only
through the
application
of the audio
signal to the R.F.
Amplifier. This
feature is
in direct
accord
with
transmitter
practice.
9. No
"Dead
Spots."
The
design
of the
"UNIT-OSCILLATOR"
(front
cover), is
such
that ALL
inductances,
not in use,
are
COMPLETELY
shorted
out of
the
circuit,
thereby
eli-
minating
signal
absorption
due
to free-floating
coils,
which would
produce
unusable
portions in a
Signal
Generator's
frequency
range.
10.
Audio
and
R.F.
Signals
Independent
of Each
Other.
This is
an
original PRECISION
"S-S-S"
feature,
whereby
the
Series
E-200-C
serves
as BOTH
an
audio
and R.F.
Signal
Generator,
at
the same
time,
with
non-
interfering
operation;
allowing
for
simultaneous
test
on
tuners
and
audio
amplifiers
by
two
separate
opera-
tors.
The
R.F.
signal
may be
used
unmodulated
while
the audio
signal
is
being
utilized
at
another
point.
This
same
independence
of R.F.
and
audio
controls
provides
complete
flexibility
of
the type of
R.F.
signal
voltage
employed.
In
other
words,
the
modulation
percentage
(and type of
modulation)
can be fr,eely varied WITHOUT
HAVING
TO
TOUCH
EITHER ONE OF
THE R.F.
ATTENUATORS.
11. Amplif ied External
Modulation
Input.
The four
position "Audio
Signal" selector switch
provides for
modulation of the R.F.
signal from exter-
nal sources, when
the switch
is
set to the "EXT.
MOD."
position.
In this position the audio oscillator
tube operates as a
high
gain
amplifier thus enabling
the E-200-C
to be adequately
modulated by low level
external signal
sources
such
as
crystal type phono-
graph
pick-ups.
12. Frequency Modulation
-
Television.
The
alignment of F.M.
receivers is readily
and easily
accomplished
directly
with the Series E-200-C. An
actual
F.M.
signal is NOT
mandatory. See page
(13).
However, when
desired, a frequency modulated
signal
for oscillographic
methods of
alignment
is
readily
ob-
tained
through the use
of Series
E
310-C or
equal
Sweep
Signal
Generator. By
connecting
the coaxial output
cable of
the Series E-200-C
to the marker input
termin-
als
of the Sweep
Signal
Generator,
E-200-C
thereby
becomes
a
variable
frequency marker signal
generator.
The fundamental
requirements
of a service-laboratory
type Signal-Marking
Generator is
to provide,
unfailing-
ly, a source
of
RELIABLE
and ACCURATE
frequency
standards for the
adjustment and
alignment of R.F.
circuits. Fulfilling
this requirement, Series E-200-C
readily provides
up-to-the-minute application as
an
A.M.
generator for
trap adjustments in
T.V. receivers
as well
as for peaking
alignment of
stagger-tuned T.V.
-I.F. stages. In
addition, Series E-200-C
is a very
convenient source
of
variable marker signals
when
aligning T.V. sets
with a sweep
signal
generator. It
furthermore permits
rapid,
accurate, overall
band width
checkup via the
moving
marker
method.
See
page
(18).
Incidentally
a
frequency
modulated
signal
generator
is best employed
only when a
high sensitivity
labora-
tory type cathode-ray
oscillograph is
also on
hand,
such as SERIES ES-550B.
13.
Fused Line Circuit.
A
special front
panel fuse post
provides full protec-
tection against the
accidental use of
improper voltage
sources and further
protects the
instrument against
prolonged high
voltage surges.
14. Tubes.
This instrument
employs one each of
the following:
6AU6
—
Electron coupled
R.F.
oscillator-amplifier.
6U8
—
Audio
oscillator-modulator, audio
amplifier,
cathode follower
output.
5Y3-Full
wave rectifier.
The foregoing, in
conjunction
with the schematic
should
give the reader a
well-rounded idea
of
the
ex-
ceptionally well
planned
background
and design
of the
Series
E-200-C
service-laboratory
Signal-Marking Gen-
erator.
3
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