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SECTION II. ASSEMBLED RECEIVER TEST
3-3. GENERAL.
This section provides procedures to check the Receiver's operation after repairs
and/or alignment have been made. The test procedures are designed to provide an
overall operational check of the Receiver and to ascertain that its functional
capabilities have not been impaired.
These tests determine power supply operation, synthesizer performance,
reference frequency accuracy, audio power and distortion, gain modes and final IF
frequency. Before the tests are conducted all repairs and reassembly should be
inspected for quality workmanship and completeness. All shields and covers should
be in place and the Receiver allowed to warm up for at least 30 minutes.
a.
Power Check.
(1)
Make sure that circuit card switch is installed correctly and proper fuse is
installed for the line voltage to be used.
(2)
Connect the power cord to the Receiver then to the power source. Set REF
IN/OUT switch on rear panel to INT.
(3)
Turn Receiver POWER switch to on and note that there is a random display
of information on the two front panel LCD's.
(4)
Make sure that all LCD back lighting lamps are on.
(5)
Make sure that the FAULT indicator is off. If this indicator is on refer to
Receiver manual 31R2-2URR-251 for information on clearing the fault.
(6)
Perform BITE check as outlined in Receiver manual 31R2 -2URR-251,
b.
Frequency Tuning and Display.
(1)
Press ENTER then press numeral keys 0, 0, 5. 0, 0, 0, O and O and note
that 0.500000 MHz is displayed.
(2)
Press ENTER then press numeral keys 1, 5, 0, 0, 0, 0, 0 and 0 and note that
15.000000 MHz is displayed.
(3)
Press TUNE RATE pus hbutton until there is no indication under tuning.
(4)
Rotate tuning knob both clockwise and counterclockwise and note frequency
displayed slowly increases with clockwise rotation and decreases with
counterclockwise rotation at a 1 Hz per step rate.
(5)
Select both SLOW and FAST tuning rates repeating step (4) for each tuning
rate; SLOW changed at a 30 Hz rate, FAST at a 1 kHz rate.
(6)
Press the LOCK pushbutton then rotate the tuning knob and note that there
is no frequency change.
(7)
Press ENTER then press numeral keys 2 and 9 and note that frequency
displayed is 29.000000 MHz.
c.
Frequency Calibration Resolution.
This test requires the digital frequency counter listed in Table 1-2.
(1)
Disconnect PI of cable W4 from J2 and A3 and using the cable coupler
connect the digital frequency counter to PI on cable W4.
(2)
Ensure that the frequency is 40 MHz j^8 Hz. This ensures that the internal
Racal RA6790/GM Alignment & Tuning Manual
Page 14 of 20
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