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ALIGNMENT
I - F S E C T I O N
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.
E O U I P M E N T N E E D E D
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.
t o . 8 l
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 S E C T I ON
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.
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