Electra bearcat IV - Alignment Procedures; IF Section Alignment; Alignment Equipment Requirements; RF Section Alignment Warning

ALIGNMENT
I-F
SECTION
Nignment
of
the
I-F
system
consists
of
optimizing the input
and output networks
and balancing
the detector
output. The
bandpass and center frequency
are
established
by quartz crystal
filters
and
"peaking"
the coils can
result
in bandpass ripple or
poor
sensi-
tivity.
Field
alignment
should not be
necessary
but the procedure
is
given
for
general information.
EOUIPMENT
NEEDED
Oscilloscope
Sweep
generator with 10.79,
10.80
and l0.BlmHz
markers
l. Connect
sweep
generator
to TP-l through a lpf capacitator.
2.
Connect
oscilloscope
to TP-3.
3.
Maintain
output of
10.B0mHz
sweep
generator
at a low level
to
prevent
distortion
from
overloading.
4. Detune
T5
for
maximum
IF output display.
See
Figure
2.
5.
Adjust
T3
for
maximum output,
and T4
for
minimum ripple.
Adjust T5
so
that 10.80
mHz is in
center
of discriminator
curve
and
for
best
linearity.
See
Figure 3.
to.8l
Figure 2
Figure 3
ALTERNATE
METIIOD:
I-F
alignment may be checked
using
a
Measurements
Model 800
Generator
or
equivalent
tuned
to an operating frequency
and swept
+
25kc. Markers
are
not
essential
since center frequency
is determined
by the filter.
R-F
SECTION
D() NC)T
ATTEMFT
ALIGNMENT
OR
"PEAKNG''
OF R-F
SECTTON.
The R-F
alignment points
are adjusted
and
sealed at the
factory
and
should
not
be
disturbed.
Factory
alignment involves
multi-frequency
signal generation systems, add-on
test modules,
output
indicators
and training
beyond
the scope of normal
service
activities.
The
unique
R-F
system inclurles
electronic
tracking
of R-F
and oscillator
circuits for
maximum
performance
over a
wide range
of
frequencies.
THIS PERFORMANCE
CAN BE
DESTROYED
BY
AN
ATTEMPT TO
"PEAK
UP''
OR
"TWEAK''
OR
"OPTIMIZE'"
ETC.
lo.
8
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