Precision E-200-C Series User Manual

fall
into the
category
of
paragraph
&
Inasmuch as
these
mftiis arc
usually
mounted
upside
down
(which
automati-
cally
reverses
the
indications
I, the
meter is
tuned for
great-
est
swing,
but
which
in
reality
corresponds to
MINIMUM
current.
Other
means
for
obtaining
resonance
indications
might
be
listed,
for there
are many
things
that
happen
in a
receiver
that
can
be
employed
as
indications
of
resonance.
However,
the
foregoing
should
be
sufficient
to
satisfy
most
require-
ments.
Once
having
decided
upon
the type
of
resonance
indicator
you
wish to
employ,
it
should be
connected
accordingly
and
receiver
circuit
adjustments
begun,
always
working
away
from
the
detector
stage
in
T.R.F.
circuits
and
from
the
second
or
third
detector
in single
or
double
superheterodyne
types.
TUNED
R.F.
RECEIVERS
(without
A.V.C.)
In
receivers
of
the
T.R.F.
variety
(and no
A.V.C.),
the
signal
generator
coaxial
output
cable
leads
are
connected
to
the
antenna
and
ground
posts of the
set with
the
appropriate
series
resistor,
condenser,
inductance or
combination
as sug-
gested
in the
set
manufacturers'
instruction
sheets.
Ground
the
receiver
(with
blocking
condenser
if neces-
sary)
to a
cold
water
pipe or
other
reliable
ground.
Make
the
first
alignment
at the
high
frequency
end
of the
broad-
cast
band,
generally
at
about
1500
or
1600
kilocycles
and
with 400
cycle
internal
modulation.
The
receiver
volume
con-
trol
should
be
kept
at
the
maximum
position.
Use
the
small-
est
R.F.
signal
and
modulation
intensity
required
for
good
output
meter
deflection.
Both
the
Signal
Generator
and
the
receiver
tuning
dials
should be
set
to
the
same
frequency.
The
shunt
trimmer
condensers
are
then
individually
adjusted
for
maximum
output
and
the R.F.
signal
input
from the
Signal
Generator
should
be
progressively
reduced to
keep
the
output
meter
pointer on
the
scale.
The
receiver
volume
control
may
also be
reduced
if it is
found
desirable.
After
all
trimmer
adjustments
have
been made,
the
process
should
be
repeated
to
assure
correct
alignment
at
whatever
frequency
has
been
selected
for
the test.
Inasmuch
as
it
was
previously
stated
that
circuit
adjust-
ments
should
always be
in
such order
that
the
operator is
working
AWAY
from
the
detector,
the
first
trimmer
to be
adjusted
therefore,
is
the one
which
is in
parallel
with
that
section
of the
ganged
tuning
condenser
which
tunes the
de-
tector
coil.
The next
trimmer to
be
adjusted
is the
one which
is
across
the
R.F.
amplifier
coil
immediately
preceding
the
detector,
and so
on
back
to
the
trimmer
across the
secondary
of
the
antenna
coil.
Adjustments
of
the
antenna
series
compensating
condenser
(if any)
need
not be
performed
until
the
receiver is
installed
in
the
customer's
home,
inasmuch
as the
purpose of
this con-
denser
is to
compensate
for
varying
antenna lengths
and
conditions.
In the
event that
the
T.R.F.
receiver,
being
aligned,
uses
slotted
end-plate
tuning
condensers,
adjustments
may
also
be
made at
the
low
frequency end
of
the
dial. Set
signal
generator
and the
receiver
tuning dials to
the
same
frequen-
cies
(this time
about
600
Kc), and
bend the
slotted
end-
plates in
or
out
for
maximum
output
meter
indications.
This
procedure may
be
repeated
at a
few
points on
the
dial, each
time
adjusting the
appropriate
slotted
end-plates.
Some
re-
ceivers
make use
of
adjusting
screws
for
movement
of these
end-plates.
TUNED R.F.
RECEIVERS
(with
A.V.C.)
If
the
T.R.F.
receiver
being
aligned
incorporates
auto-
matic
volume
control, there
are
three
basic
methods
of at-
tack,
the second
of
which
is
the most
economical
and
simple
in
apparatus
and
operational
requirements,
and
yet
assuring
positive
results;
this is
the
"A.V.C.
Substitution
Method"
previously
d> scribed.
Method 1.
Keep
the
R.F.
signal at
a
level
below
that at
which
A.V.C.
action
takes
place,
and
increase
the
modulation
percentage
to
the
point
where a
good
output
meter
reading is
obtained.
Aside
from
keeping
below
the
A.V.C.
threshold,
the
actual
process
of
alignment
is the
same
as
outlined
for
T.R.F. re-
ceivers
without
A.V.C.
This
method,
with
T.R.F.
receivers, is
capable
of
good
results due
to
the
comparatively
broad
tuning of
such
radio
sets.
The
following
methods
eliminate
the
need
of
keeping
the
input
signal at
such
small level
as to
be
below the
point
at
which A.V.C.
takes
hold.
Method
2. Open
the
common
A.V.C.
lead (as
described
on page
(8),
which supplies
the
bias to
the
R.F.
amplifier
grids,
and
obtain the
appropriate
fixed
negative
potential
from the
A.V.C.
substitution
pin jacks.
A
strong
signal,
in
keeping
with actual
local
receiving
con-
ditions,
may
now be
employed
and
alignment may
then
be
accurately
attained
without
undesirable A.V.C.
leveling
ac-
tion. The
actual
modulation level
and R.F.
signal
intensity
required
for
good
initial output
meter
deflection are
de-
pendent
entirely
upon
the original
degree
of
misalignment
or
mistracking,
and
the
overall
gain of the
receiver. The
R.F.
input
signal
should be
reduced
as the
tuned
stages
are
individually
brought
into
adjustment.
Method
3. This
third
method
makes
use of
resonance
indicator
#2 as
outlined
on page
(9)
and
requires a
high
resistance
voltmeter (20,000
ohms
per
volt) or
V.T.V.M. to
measure
the
actual
A.V.C.
voltage
developed.
Adjustments
are
made
until
a
peak
reading
is
obtained,
inasmuch as
10

Precision E-200-C Series Specifications

General

Brand	Precision
Model	E-200-C Series
Category	Portable Generator
Language	English