sound
and
picture
traps,
picture
carrier
midpoint, ap-
propriate
video
I.F.
knee
points, and
all
sound
chan-
nel
I.F.
and
Discriminator
curves.
Because
the
E-200
Series
is
a
continuously
variable
Pip
Generator,
all
points
on
Video
I.F.
and
Sound
response
curves
can
be
checked
for
waveshape
configuration
and
for
band-
width.
MARKER
GENERATOR
APPLICATION
NOTES
A.
To
connect
the
E-200-C
for
use as
a
Marker or
"Pip"
Generator
either one
of the
following
methods
can be
used
:
a)
Connect
the
E-200-C
output to
the
Sweep
Signal Gen-
erator
terminal
provided for
external
marker
signal in-
jection.
Set
E-200-C
to
required
marking
frequency.
Adjust
E-200-C
output
controls
(and
Sweep Gen-
erator
marker
amplitude
control)
to
yield
a
visible
marker
pip on
the
oscilloscope
pattern.
b)
Connect
both^
'Ifltw
Ifflfl
.STTnH
leat* s of the
E-200-L
outputcable
directly
to the
receiver
chassis,
spacing the
clips
approximately
6 to 8
inches
apart.
I ocate
the
clips on
the chassis
such as to
straddle the
Sweep
Generator
injection point.
This method sets
up
strong
circulating
ground
currents
in the
receiver
chassis
which
effectively
introduces the
marker
with
a
minimum of
response curve
distortion.
B.
Marking
Discriminator Response
"S"
Curves. The
mid-frequency point of a Discriminator or
similar
F.M. de-
tector is a zero
voltage output point. As a
result, a marker
pip at this
point is difficult to discern.
If, however,
the
A.M.
Generator is
set
for "MOD.
R.F.," strong
modulation "wig-
gles" will appear at
either end of the
response curve when the
marker locates on
any point of
the curve EXCEPT the
midpoint. As the
marker frequency is
adjusted
to
locate at
the
curve
midpoint, the amplitude of the wiggles
will
de-
crease
reaching
a
minimum when the marker finally
lo-
cates
AT
the mid-frequency
point.
C. Marking
Sound and Pictur
e
Traps.
The method
de-
cribed in (B)
may also be used
to advantage in the mark-
ing
of Sound
and Picture traps. With
the E-200-C
set to
"MOD. R.F.," the
modulation "wiggles"
will diminish
to a
minimum
as the
marker pip descends
into the
trap
valley.
D. Methods
for
improving visibility
of Marker
pips.
a) Do not use excessively strong Sweep
Generator
out-
put. Strong Sweep Generator
output
requires
de-
creased
set
sensitvity,
thus reducing
the
visibility of
the marker.
b) Markers on
the
Steep
portions of a response
curve
are
normally somewhat difficult to
discern. Reduce the
Sweep Width of the
Sweep Generator, thereby "ex-
panding"
the
portion of
the trace to be observed.
.
c) Use the
"circulating ground
current" injection
meth-
od
just
described at A (b).
Increase the
spacing be-
tween the E-200-C output cable
alligator
clips
to
in-
crease the amplitude of
the marker.
SPECIAL
NOTES
External Modulation
of the
R.F.
Signal
The
four position "AUDIO
SIGNAL" switch
at the
lower
right hand
corner of the Series E-200-C
panel pro-
vides for
modulation of the R.F. signal from an external
source,
when the
switch
is set to the
"EXT.
MOD." posi-
tion. The
"MOD. CONTROL"
still determines the
actual
percentage of modulation, although the settings for the
various levels will naturally differ from
those
given
for the
internal 400
cycle modulation. This
is readily understand-
able
when
it
is realized that it is highly
improbable that
the external source of modulation will
be
of the
same
peak
voltage
as
that of the internal audio oscillator.
18
To Next Page
Loading...
Need help?
General