21
8 TUNE–UP AND ADJUSTMENTS
NOTICE
This equipment was thoroughly tested and inspected at the factory prior to shipment.
Adjustments should rarely be necessary in the field and should only be attempted by highly
trained technicians familiar with this type of equipment. Laboratory grade test equipment is
required and is listed under TEST EQUIPMENT AND TOOLS.
The following text presents the adjustment procedures for the SR–30/SR–40A receivers. Do not adjust
any other controls in the unit. Refer to component locator 597–8104–3 in the SCHEMATIC AND
ASSEMBLY DRAW- INGS section as required for the following procedures.
8.1 IF Amplifier/Detector Circuit Board Adjustments
WARNING
AC LINE VOLTAGE IS PRESENT ON THE POWER SUPPLY TERMINAL STRIPS.
DO NOT TOUCH THE TERMINAL STRIPS DURING THE FOLLOWING
ADJUSTMENT.
1. Connect the RF signal generator to the ANTENNA input. Adjust the signal generator for; 1) the
desired operating frequency, 2) an output level of 4 mV, and 3) no modulation.
2. Connect a voltmeter between IC1–13 and ground.
3. Adjust coil L1 for a +5.0 v dc indication on the multimeter.
4. Connect a voltmeter between J1–3 and ground.
5. Adjust potentiometer R18 for a +4.0V dc indication on the multimeter.
6. Connect the distortion analyzer to the receiver audio output at J4.
7. Adjust the RF signal generator for: 1) an output level of 100 uV and 2) modulation using a 400 Hz
tone with a 5.4 KHz deviation. The deviation will vary depending on the bandwidth of the unit.
8. Adjust the primary and secondary coils of T1 for minimum distortion and maximum output level on
the analyzer.
9. Remove the test equipment.
8.2 Decode Board Circuit Board Adjustments
WARNING
AC LINE VOLTAGE IS PRESENT ON THE POWER SUPPLY TERMINAL STRIPS.
DO NOT TOUCH THE TERMINAL STRIPS DURING THE FOLLOWING ADJUSTMENT.
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