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34. FM IF ALIGNMENT
Test Equipment/Tools
Rsquired
*
10.7 MHz
Sweep/Marker Generator
*
Oscilloscope
:
*
1kQ
carbon type resistor
*
Screwdriver for Alignment
Preparation:
Sweep/Marker Generator Connection:
On the main circuit board with 1k
resistor in series (See Fig. 3-4).
Oscilloscope Connection:
MPX OUT jack
Sweep Generator Center Frequency:
10.7 MHz
Marker Generator Center Frequency:
10.7 MHz
Band Selector:
FM2
sweep /marker
generator
Sweep/Marker
Generator Coupling
Sweep/Marker
Generator Frequency
Oscilloscope
Connection
| CRF-2305
1
Procedure:
1. Turn the core of discriminator transformer
(IFT 204) fully counterclockwise.
2. Turn
the
core
of
fm
i-f
transformer
(IFT 201, IFT 202) and discriminator trans-
former (IFT 203) to obtain
the maximum
amplitude response curve shown in Fig. 3-5.
3. Turn the core of discriminator transformer
(IFT 204)
to obtain
the S curve
response
shown in Fig. 3-6.
10.7MHz
x
marker
Bp
Fig. 3-5
Response curve
10.7 MHz
&
marker
Fig. 3-6
"S" curve
Adjust
Remarks
—
On the main circuit
board with 1ka
resistor in series,
(See Fig. 3-4)
10.7 MHz
MPX OUT jack
1FT204
IFT203
1FT202
Band
Selector:
FM2
IFT201
AFC Switch:
off
IFT202
:
IFT203
IFT204
Adjust
for maximum
amplitude
and
symmetrical
S curve
on the
scope.
Fig. 3-7
Adjusting parts location
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